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Recycled Aggregate Concrete (RAC) has attracted considerable attention for its potential to conserve natural resources and mitigate carbon emissions. Nevertheless, the widespread adoption of RAC in the construction industry faces challenges associated with its inherent performance deficiencies, including the formation of pores and microcracks in the recycled aggregate (RA) generated during the crushing process, as well as the presence of dual interfacial transition zones (ITZ) within the internal structure of RAC. The incorporation of fibres as reinforcement offers a promising solution to improve the performance of RAC. The paper begins with a comprehensive examination of various fibre properties and recycled aggregates. Then, summarizing the impact of fibres on RAC's performance. Special emphasis is placed on analyzing the influence of mixed fibres on the mechanical properties of RAC. The introduction of a blend of low-strength and high-strength fibres demonstrates the potential for further improving the mechanical properties of RAC beyond the benefits offered by individual fibres. This blending strategy also enhances the multiscale crack resistance of RAC, attributed to the collaborative effects of various fibres at different load stages. The reinforcing mechanism at the micro-scale of RAC is also discussed. Finally, the paper outlines perspectives for future research. [Display omitted] • A comprehensive review of hybrid fibre reinforced recycled aggregate concrete. • The effects of a single type of fibre on mechanical properties and microstructure. • Combining high-strength and low-strength fibres shows positive effects. • Blended fibres induce a dense C-S-H gel phase, enhancing cracking resistance. • The economic and environmental impacts are discussed. [ABSTRACT FROM AUTHOR]

The outbreak of the COVID-19 epidemic has led to a large number of waste disposable medical face masks (DMFMs) worldwide, which seriously pollute the environment and threaten human health. In this paper, waste DMFMs were recycled as mask fiber and mixed into self-compacting recycled aggregates concrete (SCRAC) to form a mask fiber reinforced self-compacting recycled aggregates concrete (FRSCRAC). The effects of recycled coarse aggregate (RCA) replacement ratio, DMFM fiber content, and length on the working and mechanical properties of FRSCRAC were investigated. The results show that the specimens meet the requirements of self-compacting concrete (SCC) in terms of working and mechanical performance, but the RCA and DMFM fiber could reduce the workability of the FRSCRAC, and the higher the amount of RCA and DMFM fiber, the more obvious the reduction. At the same time, the mechanical properties of FRSCRAC increased as the decreasing RCA replacement ratio and growing DMFM fiber content. Compared with specimens without DMFM fiber reinforcement, the compressive strength, split tensile strength, flexural strength, and elastic modulus were increased by 1.3%-9.6%, 1.46%-8.6%, 24.4%-54.69%, and 0.65%-4.73%, respectively. Moreover, the reduction of the DMFM fiber length is favorable to the mechanical properties of FRSCRAC as well. Furthermore, the X-ray CT and scanning electron microscope (SEM-EDS) techniques were applied to analyze the microstructure of typical specimens. The results showed that the DMFM fiber and surrounding mortar could form a multiphase composite, which reduces the porosity and improves interfacial stress transfer efficiency, thus enhancing the mechanical properties of FRSCRAC. In addition, based on the experimental results, the mechanical strength index of FRSCRAC and the calculation formula of its mutual conversion relationship were proposed. The research conclusions of this paper can provide a reference for the application of waste DMFM fibers in FRSCRAC. • Waste disposable medical face masks were recycled as fiber and mixed into self-compacting recycled aggregate concrete. • Parameters were investigated to make clear the influential mechanisms of waste fiber on recycled concrete performance. • The mechanical strength index of FRSCRAC and the calculation formula of its mutual conversion relationship were proposed. [ABSTRACT FROM AUTHOR]

Engineered Cementitious Composites (ECC) utilize the bridging effect of high toughness fibers to improve the brittle failure of concrete materials, achieve the effective control of cracks in cementitious materials, and significantly improve the deformation capacity. In view of the multi-stage crack-blocking effect of different fibers incorporated in ECC materials, 91 ECC specimens of steel-polypropylene hybrid fiber by mixing steel fiber (SF) and polypropylene fiber (PPF) into cement-base are made in this paper. The specimens are tested in compression, tensile, bending and damping properties, respectively, which is of great significance to study the response of ECC structures under the earthquake action. The effects of the volume content of SF and PPF on the mechanical properties of ECC are studied in this paper. The results show that the cube specimen has better ductility than the prismatic specimen under monotonic compression, and there is no obvious brittle failure. With the increase of the volume content of SF to PPF, the compressive strength and elastic modulus of hybrid fiber ECC gradually increase, while the corresponding strain and axial compressive toughness gradually decrease; the tensile strength and tensile modulus increase, while the bending strength and damping ratio decrease. According to the test results, constitutive models of monotonic and repeated loading of hybrid fiber ECC suitable for finite element (FE) analysis are proposed. This investigation provides a theoretical basis and an experimental reference for further study of steel-polypropylene hybrid fiber ECC. • Steel fiber and polypropylene fiber are mixed as hybrid fiber of ECC. • The mechanical properties of ECC are investigate. • Volume content of steel-polypropylene hybrid fiber has influence on concrete material. • The hybrid fiber ECC cube has better ductility than that of prismatic. • Constitutive models of hybrid fiber ECC are suitable for finite element analysis. [ABSTRACT FROM AUTHOR]

This paper presents a thorough investigation into utilizing hybrid fibers, comprising both steel and polymeric fibers, to enhance the compressive and tensile behaviors of ultra-high-performance concrete (UHPC). Flowability tests revealed potential usability challenges with polymeric fibers, emphasizing the necessity for careful consideration. Compressive strength results demonstrated that hybridizing straight steel fibers with short hooked steel fibers results in performance similar to that of reduced steel fiber content. Elastic modulus trends correspond with those of the compressive strength, and unexpectedly positive effects on the ultimate strain capacity under compression are observed with long polyvinyl alcohol fibers. Tensile behavior analysis highlights the superiority of both short and long hooked steel fibers, with the latter contributing the highest tensile strength. However, the use of polymeric fibers significantly decreases the tensile strength owing to insufficient dispersion and low tensile strength. Scanning electron microscopy images of UHPC with polymeric fibers reveal debonding and surface damage, with potential advantages observed for polypropylene fibers through methods such as surface moisture coating. In conclusion, this paper provides insights into optimizing fiber content and types for UHPC, emphasizing a balance between reduced fiber content and maintained performance. The proposed hybrid reinforcement approach, particularly with short hooked fibers, is promising for practical usability and cost-effectiveness in construction applications. • Addition of hybrid fibers, particularly polymeric fibers, results in a decrease in flowability. • Hybridizing with hooked fibers decreases the fiber content by 0.5 % given similar strength levels. • Long PVA fiber is effective in increasing elastic modulus of UHPC due to limited deformation. • Hybrid use of straight and hooked steel fibers exhibits improved tensile performance of UHPC. • Introduction of PVA and PP fibers causes a decrease in the tensile strength of UHPC. [ABSTRACT FROM AUTHOR]

Fully utilizing regional resources such as marine sand, coral, and desert sand, along with a diverse range of solid wastes from industries, agriculture, and urban areas, not only effectively reduces the costs and carbon footprint of construction activities but also contributes to achieving sustainable development in the building sector. Despite earlier studies focusing on the feasibility of solid waste as lightweight aggregates, the comprehensive evaluation of the performance of alternative aggregates in such innovative materials as geopolymers and ultra-high-performance concrete remains significantly limited amid their rapid development. Therefore, this paper concentrates on a thorough exploration of regional sand and gravel resources, as well as efficient and value-added approaches to incorporating solid wastes from industries, agriculture, and urban areas as alternative aggregates in construction. It provides a comprehensive review of the physical properties of alternative aggregates and their impacts on the workability, mechanical properties, and durability of concrete. Additionally, the paper offers a detailed assessment of the production processes and performance of sintered and cold-bonded artificial aggregates. This research provides valuable insights for researchers and practitioners in the fields of construction, sustainable waste management, resource conservation, and recycling. • Regional resources, industrial and agricultural and urban solid wastes are used as clean aggregates. • Potential legal challenges to the use of clean aggregates are revealed. • Reviewed the modification methods of granular solid waste. • Reviewed artificial agglomeration techniques and potential challenges for powdered solid waste. [ABSTRACT FROM AUTHOR]

Basalt fiber (BF) is an emerging environmentally-friendly fiber. Adding basalt fiber can improve the deficient recycled concrete's poor mechanical properties and durability. By reviewing nearly 120 related papers, the effects of variables such as BF content and length (0–1.5%, 9–18 mm), recycled aggregate substitution rate (0–100%), and cement mix ratio (w/b, 0.25–0.45) on the mechanical and durability properties of basalt fiber-reinforced recycled concrete (BFRAC) were discussed. Due to the presence of vulnerable interfacial transition zones, the mechanical properties of recycled concrete (RAC) continuously deteriorate over time. However, by adding an appropriate amount of basalt fiber, it is possible to improve these structural defects by forming a network structure that enhances cracking resistance within the matrix and improves interface bonding strength among other benefits. Consequently, this significantly improves the overall mechanical properties of RAC. Additionally, while incorporating recycled aggregate (RA) may reduce compressive strength initially, this deficiency can be mitigated through the proper inclusion of fibers in RAC mixtures. Optimal compressive strength for RAC is achieved with a replacement ratio between 25–50% and a fiber content ranging from 0.2–0.3%. Furthermore, properly incorporating fibers into RAC greatly enhances splitting tensile strength and flexural strength as well; specifically achieving optimal splitting tensile strength with a replacement ratio between 40%− 50%, a fiber content at 0.3%, and utilizing fibers with lengths measuring approximately 12 mm long. The primary cause for poor frost resistance in RAC lies within numerous micro-cracks and pores present in RA aggregates which lead to high water absorption rates ultimately reaching critical water saturation points resulting in freeze-thaw damage occurrences during exposure to freezing conditions. When exposed to sulfate attack, RAC undergoes a chemical reaction with sulfate ions present in the concrete, leading to the formation of numerous expansion products that negatively impact concrete performance. Progressive dehydration of hydration products under high-temperature conditions leads to a porous structure within the concrete matrix. Incorporating fibers can impede microcrack expansion during freeze-thaw, sulfate attack, and high-temperature environments, thus enhancing the erosion resistance of RAC. Compared to conventional concrete, interfacial bonding in RAC is less tight and more vulnerable to damage in complex environments. Current research on RAC suggests that the mechanism behind its damage under complex freeze-thaw load coupling environments remains unclear. It is recommended that future studies combine large-scale component tests with computational simulations to address this issue. • This paper discusses the mechanical properties and durability of BFRAC. • Numerous micro-cracks and pores in RA cause high water absorption. • When exposed to sulfate attack, CH reacts with SO2- 4 to form expansion products. • Hydration products' dehydration at high temperatures results in loose of concrete. • BF inhibits the growth of microcracks and enhances its erosion resistance. [ABSTRACT FROM AUTHOR]

Mesoscale modelling is a promising tool to analyse the phenomenological causes of mechanical failure of recycled aggregate concrete (RAC). Most mesoscale models of RAC are two-dimensional (2D) and 3D models are lacking. This prevents the full understanding of the behaviour of each mesoscopic phase. This paper presents a 3D model of RAC and analyses its mechanical behaviour based on mesoscale phenomena. The analyses concern three types of tests carried out in concrete specimens: uniaxial compressive, uniaxial tensile and splitting tensile strength tests. The mechanical response and fracture behaviour of each mesoscopic phase is analysed in relation to the response of RAC specimen. The comparisons between uniaxial behaviour of 3D and 2D modelling as well as between uniaxial and splitting tensile behaviour of RAC are presented. The main findings of the paper are: (1) the full curve of uniaxial stress-strain response from 3D modelling is comparable to that from 2D modelling for RAC (therefore, 2D models are validated for RAC modelling); (2) the overall behaviour of the concrete elements remains elastic regardless of the fracture development in the ITZ and attached mortar of recycled aggregates until damage propagates to the new mortar matrix; (3) a relationship between modelled uniaxial and splitting strength of RAC is established and validated. [Display omitted] • Realistic mesostructural model of RAC - particle size, attached mortar content and ITZ with real thickness. • Replicate the strength test of uniaxial compression, uniaxial tension, and splitting tension. • Validate the use of 2D model through comparison of the outcomes from 2D and 3D models. • The influence of each mesoscopic phase on the overall mechanical behaviour of RAC. • Establish the relationships between the modelled uniaxial and splitting tensile strength. [ABSTRACT FROM AUTHOR]

Fiber reinforced thermoplastic composites have many advantages, such as repeated molding, high toughness, durability and recyclability, which made them a potential substitute as engineering strengthening materials for thermosetting composites. However, their long-term performances under complex service environments are not well understood, hindering its durability design. In the present paper, glass fiber reinforced polypropylene (GFRPP) plate was studied on its mechanical property evaluation subjected to water immersion (distilled water) and bending (bending strains of 0.54 % and 1.04 %) at elevated temperatures (40 °C, 60 °C and 80 °C) up to 180 days. Water uptake, mechanical properties, thermal properties and microstructure tests were further carried out to reveal the effects of water uptake content, immersed temperature and bending loading level on the properties. The results showed the water absorption curve at three temperatures presents a two-stage diffusion behavior. After the longest immersion time of 180 days, the strength retention of plate at 40 °C, 60 °C and 80 °C were 88.2 %, 58.3 % and 31.8 % for tensile strength, 83.6 %, 67.8 % and 47.9 % for flexural strength and 70.6 %, 61.7 % and 41.4 % for in-plane shear strength. Higher immersion temperature accelerated the swelling effects of polypropylene. Higher bending loading levels accelerated the crack or defects formation and propagation in the resin as well as at the interface. When the strength retention rates were 50 %, the longest service life of plate exposed in service environment of Da Lian (T=9.2 °C) were 23.9 years (tensile strength), 12.8 years (flexural strength) and 3.0 years (in-plane shear strength) without the bending strain. Through comparing with thermosetting composites, glass fiber reinforced polypropylene has almost close or higher tensile strength retention rate and service life for certain service conditions. • The maximum water absorption and diffusion coefficient of composites were lower than epoxy or polyurethane based composites. • Higher immersion temperature accelerated the swelling effects of polypropylene. • Higher bending loading levels accelerated the crack or defects propagation in the resin as well as at the interface. • When the strength retention rates were 50 %, the longest service life of tensile strength were 23.9 years. [ABSTRACT FROM AUTHOR]

Even though the demand for utilizing geopolymers is growing, the need for current standard guidelines to regulate compliance to address the complexity of the mix design could be one of the major hurdles of utilizing geopolymers vastly in construction. There is no straightforward standard that addresses the complexity of the mix design of geopolymers. Thus, this work addresses main factors affecting the compressive strength of slag based geopolymers and provide a tool for predicting it. This article includes experimental work to evaluate the properties of slag-based geopolymer binders and the development of a model using Artificial Neural Network (ANN) algorithms for predicting the performance of these slag-based geopolymer binders. In this paper, we have utilized and developed ANN models for optimizing slag-based geopolymer mixes based on precursor materials' physiochemical properties and activation solutions constituents that can enhance performance compressive strength prediction in construction applications. • A high-accuracy DOE model was developed and used to characterize the Geopolymeric paste. • A developed ANN model was superior in forecasting the compressive strength of AAS systems. • The choice of the alkali activator has minimal impact on the compressive strength. • The optimal water-to-slag ratio is approximately 0.28. • The optimal alkali oxide concentration is 6 %. [ABSTRACT FROM AUTHOR]

Adding a certain amount of steel fibers can overcome the brittleness defects in geopolymer concrete and improve the mechanical properties, which has a broader application prospect. However, the research on the material properties of steel fiber-reinforced geopolymer concrete (SFGPC) after high temperature exposure is still very limited. Therefore, tests on 114 cubes and 57 prisms after exposure to high temperatures were conducted in this paper. The main variables were temperature (20 °C, 200 °C, 400 °C, 600 °C, and 800 °C), steel fiber volume content (0, 1 %, and 2 %), and concrete type (SFGPC and steel fiber-reinforced ordinary Portland cement concrete (SFOPC)). The results indicated that SFGPC with a steel fiber content of 1 % at 800 °C experienced a 53.6 % reduction in compressive strength, a 58 % reduction in splitting tensile strength, a 93.9 % reduction in elastic modulus, a 45.9 % reduction in toughness index, and a 274.5 % increase in peak strain, compared with room temperature. The 1 % fiber content enhanced the compressive strength by 10.3 %−36.5 %, the splitting tensile strength by more than 16 %, the peak strain by 9.6 %−32.7 %, and the toughness index by 24.4 %−64.6 % compared to the absence of fiber content. Based on the room temperature model, a constitutive model of SFGPC under uniaxial compression after high temperatures was developed. • Cubes and prisms of SFGPC after high temperature exposure were tested. • High temperature reduced the strength, elastic modulus, and toughness index. • Increasing fiber content enhanced the mechanical behavior of SFGPC. • A constitutive model under compression after high temperatures was developed. [ABSTRACT FROM AUTHOR]

Glass fiber reinforced plastics (GFRP) have been widely used in the field of civil engineering infrastructure, while it also generating a large amount of waste glass fibers simultaneously. This paper uses waste glass fiber in self compacting recycled concrete (SCRC), forming a kind of waste glass fiber reinforced self-compacting recycled concrete (RGF-SCRC). The effects of recycled coarse aggregate (RCA) replacement ratio, water to binder (W/B) ratio, the content and type of glass fiber on the working and mechanical properties of RGF-SCRC were investigated. The results showed that the specimens could meet the requirements of self-compacting concrete (SCC) in terms of working performance, but the addition of RCA and glass fiber could reduce the workability of RGF-SCRC, when RCA is replaced with 100 % and the fiber content reaches 10 kg/m3, the slump expansion is reduced by 9.5 % and 12.4 %, respectively. The mechanical properties of RGF-SCRC decreased as the growing value of RCA replacement ratio and the W/B ratio, among them, the elastic modulus decreased the most, by 40.4 % and 30.0 %, respectively. Compared with the results of the control specimen, the properties could be improved significantly under an appropriate content of waste glass fiber: the cube compressive strength, splitting tensile strength, flexural strength, and elastic modulus of RGF-SCRC were increased by 1.3∼9.6 %, 13.5∼59.4 %, 17.8∼40.9 %, and 3.3∼13.4 %, respectively. However, excessive fiber content showed a negative effect on the mechanical properties. Specimens with the 7.5 kg/m3 alkali resistant glass fiber content showed the best mechanical properties. Moreover, the X-ray CT and scanning electron microscope (SEM) techniques were applied to explore the influencing mechanism of waste glass fibers on RGF-SCRC. The results showed that after adding an appropriate content of waste glass fiber, the porosity and the number of large pores decreased, and the pore size and distribution became more reasonable, which enhanced the compactness of RGF-SCRC to some extent. The mechanical force and friction force anchored at the fiber end at the interface with the concrete matrix increase the bonding strength, thereby enhancing the mechanical properties of RGF-SCRC. This study achieve the resource utilization of waste glass fiber and improve the mechanical properties of concrete and the research results can provide a reference for the practical application of RGF-SCRC in civil engineering. • The waste glass fiber was applied in self compacting recycled concrete (SCRC). • Various parameters were investigated to make clear the influential mechanisms of glass fiber on the working and mechanical properties of waste glass fiber reinforced self-compacting recycled concrete. • The enhanced mechanism of fiber addition on SCRC was illustrated by the microstructure method and analysis. [ABSTRACT FROM AUTHOR]

When constructing concrete structures using 3D printing, it is important to consider the anisotropy due to the printing process. The print path influences the formation of layer interfaces and inter-filament voids, and the fracture propagation behavior of the printed specimen. In this paper, the fracture propagation behavior of printed mortar specimens under compressive, tensile, and bending stresses is evaluated for different print paths. X-ray computed tomography visualizes the interior of printed specimens and shows that the pressure during material extrusion elongates the intra-filament voids. The inter-filament void structure is influenced by the print path, forming an aligned structure in one direction or a complex lattice-like structure. Anisotropy in the deformation direction under compressive stress, which is influenced by the inter-filament void structure, is assessed by 3D scanning. Under tensile stress, Digital Image Correlation (DIC) visualizes that tensile stress is concentrated in the layer interface, causing cracks to propagate along the layer interface. Under bending stress, DIC evaluates the effect of the print path on fracture propagation behavior. The results show that the mechanical properties and fracture propagation behavior of printed specimens are affected by the arrangement of the layer interface and inter-filament void, which is governed by the print path. (200 words) • Layer interface arrangement and inter-filament void structure, influenced by print path, affect the mechanical properties of 3D printed concrete. • Anisotropic deformation of 3D printed specimens due to print paths can be evaluated by 3D scanning surfaces before and after loading. • DIC with a high-speed camera evaluates instantaneous bending fracture, strain distribution, and crack propagation behavior in printed specimens. [ABSTRACT FROM AUTHOR]

Chloride-induced deterioration of reinforcing steel bars has become a densely researched topic over the past several decades because of the severe ramifications to the structural reliability of aging infrastructure. The ever-growing volume of experimental and field data continually enables advances in the field through deeper micro-macro analyses and various modeling applications. The purpose of this paper is twofold. First, an experimental program is introduced, describing the tensile testing of 284 artificially corroded, 25 mm diameter deformed Grade500E reinforcing bars. Secondly, the mechanical characteristics of corroded bars are predicted through a collection of regression-based machine learning algorithms. Models are trained and tested on a database of 1387 tensile tests compiled from 25 other experimental programs available in the literature. The complete database includes 19 input parameters used to predict nine key mechanical properties of the corroded steel bars. Nine machine learning models were selected from a balanced assortment of algorithm typologies to determine the most appropriate methodology for each response variable. The adaptive-neuro fuzzy inference system (ANFIS) model was found to have the strongest individual predictive ability across all models. Meanwhile, ensemble tree-based learning algorithms categorically provided the most consistently high-performing models over the selected response variables. • Monotonic tensile testing was performed on 284 artificially corroded steel rebars. • A database of 1387 tensile tests is compiled from 26 experimental programs. • Comparative analysis on the predictive capability of nine machine learning methodologies. • Adaptive-neuro fuzzy inference systems demonstrate the strongest individual ability. • Tree-based models categorically provide the most consistently high-performing models. [ABSTRACT FROM AUTHOR]

To further enhance our understanding of the microstructure of SRM and its intrinsic relationship with macroscopic properties, this paper conducted indoor freeze-thaw cycles, EIS and uniaxial compression tests. The results indicated that the number of freeze-thaw cycles has a significant exponential relationship with R CPP , R CPP 1 and C DSRP. As the number of cycles increased, R CPP and R CPP 1 exhibited a decreasing trend, whereas C DSRP showed an increasing pattern. The freeze-thaw cycles led to the expansion and connection of different pores, resulting in the widening or multiplication of channels in CPP , leading to a decrease in both R CPP and R CPP 1. However, in DSRPP , the liquid-filled pores underwent radial expansion during freeze-thaw cycles, connecting with gas-filled pores around them. This transition led the conductive path to transform into CPP , reducing the accumulated thickness of non-continuous points. Consequently, C DSRP exhibited an increasing trend. Furthermore, the increase in porosity weakened the deformation resistance, increasing the compaction stage of pores and the peak strain, while reducing its peak strength and secant modulus. The peak strength, strain and secant modulus also exhibited significant exponential relationships with different cycles. There was a good exponential correlation between ∆ R CPP of CPP and the uniaxial strength, and the freeze-thaw deterioration model constructed with it as an influence factor could better assess its peak mechanical strength after freezing and thawing. • An electrochemical circuit model for different conductive paths was proposed. • The microstructure was characterized by EIS parameters of the equivalent model. • The influence and mechanism of freeze-thaw cycles on EIS parameters were analyzed. • A degradation model for the uniaxial strength was established with EIS parameters. [ABSTRACT FROM AUTHOR]

In the exploration of the moon and outer space, our preliminary mission lies in the construction of lunar base. To make lunar concrete with local materials on the moon becomes the key technology to promote the construction of lunar bases. In order to further study the feasibility of using lunar in-situ resources to prepare concrete and build a lunar base, the environment and resources on the lunar surface are analyzed, and the severe challenges brought by extreme environment to concrete preparation and the prerequisites of in-situ resources are clarified. In this paper, the research progress of lunar concrete is summarized from the aspects of raw material acquisition, concrete preparation methods and performance, and the comparative analysis of cement concrete, sulfur concrete, geopolymer concrete and polymer concrete is carried out. Existing studies have shown that in the acquisition of raw materials, sulfur concrete has more advantages, cement concrete and geopolymer concrete are also feasible, but polymer, as a scarce resource on the moon, is difficult to obtain. In terms of preparation methods, cement concrete and geopolymer concrete are more suitable for the production of prefabricated components in artificial environment due to the limitation of external environment and the demand of water circulation, while the in-situ preparation methods represented by sulfur concrete and polymer concrete can be used for the connection and node reinforcement of prefabricated components on the moon. In terms of performance, the mechanical properties of the four kinds of concrete all meet the basic requirements, but the service performance in the harsh environment of the moon needs to be further studied. Meanwhile, the key location characteristics for lunar base construction in different regions are analyzed in terms of topography, environment and in-situ resources. Finally, the future exploration direction of the construction of the lunar bases is proposed. • Comparative study on lunar concretes: cement, sulfur, geopolymer, and polymer. • Sulfur concrete's raw material acquisition advantage; polymer's scarcity on moon. • Prefabrication versus in-situ production methods for lunar habitat construction. [ABSTRACT FROM AUTHOR]

Sand instability is always an intractable problem in geotechnical engineering and its reinforcement using additives is an effective method. This paper introduces the organic polymer reinforcer (OPR) and the recycled polypropylene fiber (RPF) to modify sand. The unconfined compression and corresponding numerical tests were performed to investigate mechanical properties, deformation failure behavior, and microscopic response. Results showed that both materials positively affect the mechanical and deformation properties of modified sand synergistically. Optimized particle structure by the inter-particle polymer membrane linked the loose sand into a whole with fibers as a framework. Strain-softening properties were reduced with less strain localization under loading. This is also clearly related to the improvement of the micro-damage based on numerical results. OPR-RPF reinforcement transformed the bond failure from unidirectional concentration to multilocal dispersion by improving force chain construction, microcrack propagation, and energy allocation. Thus, the failure of modified sand showed a macroscopic progression from shear-faulting via ductile-faulting to ductile flow. Future research lies in further considering the particle shape and pore structure variations to provide new insights for a deeper understanding of sand stabilization mechanisms and engineering applications. [Display omitted] • OPR-RPF treatment synergistically enhances sand's strength and failure resistance. • OPR and RPF content each influenced the micro-damage response of the modified sand. • Multiple interactions improve force chain, cracking, and energy response. • The bonding and framework effects favored homogeneity mitigating strain localization. [ABSTRACT FROM AUTHOR]

A type of new stainless steel, namely QN1803, has been developed in recent years. The elevated temperature mechanical properties of QN1803 stainless steel were experimentally investigated and presented in this paper. The test programme includes a series of elevated temperature material tests and some room temperature material tests as control groups. The elevated temperature tests adopted the steady-state testing method and transient-state testing method. In the steady-state tests, nine temperature levels ranging from 100 °C to 900 °C with 100 °C interval were considered. In the transient-state tests, ten stress levels ranging from 0.1 f p,0.2 to 1.0 f p,0.2 with 0.1 f p,0.2 interval were considered. Key mechanical properties were obtained from the tensile coupon tests, and the results from the two different testing methods were compared. The reduction factors of the key mechanical properties and a two-stage R-O material model was provided for QN1803 stainless steel based on the obtained test results. These outcomes provide a fundamental reference for further research studies on the structural behaviour of QN1803 stainless steel in fire. • Elevated temperature mechanical properties of QN1803 stainless steel were firstly investigated. • Steady-state tests and transient-state tests were conducted. • Reduction factors of key mechanical properties were provided. • An elevated temperature material model was suggested for QN1803 stainless steel. [ABSTRACT FROM AUTHOR]

The low water-cement ratio has a significant effect on increasing the compacted density of the concrete, thereby enhancing its mechanical properties and microstructures. This paper introduces an innovative approach of utilizing the cold isostatic pressing method to prepare reactive powder concrete (RPC) specimens with an ultra-low water-cement ratio which not exceeds 0.16. And it is compared with the specimens prepared by the traditional vibrational method which conversely requires the minimum water-cement ratio of 0.21. The results show that the RPC specimens under cold isostatic pressing exhibit enhanced compressive strength and microhardness, as well as improved matrix compactness. Conversely, the RPC matrix produced under the vibrational method not only contains a small number of air-entrained bubbles that can influence the strength of matrix but also exhibits a significantly larger cumulative volume of harmful pores that affect the performance of RPC compared to cold isostatic pressing. Therefore, cold isostatic pressing technology based on all-directional hydroforming is a powerful tool for the preparation of high-strength RPC, which significantly reduces the internal defects of the specimen, and the prepared RPC has superior mechanical properties and matrix structure. • Significant increase in the compressive strength of RPC has been achieved by cold isostatic pressing. • The molding method has a significant influence on the Vickers hardness of RPC. • The hydration reaction of cold isostatic pressing specimens after autoclave curing is still incomplete. • Specimens prepared by cold isostatic pressing exhibit dense matrix without air-entrained bubble observed. [ABSTRACT FROM AUTHOR]

Fiber reinforced thermoplastic composite bars offered the advantages of repeated molding, high toughness, and recyclability, making them a promising alternative to steel bars. For the stirrups applications in concrete structures, it was essential to develop efficient bending technologies for producing high-quality thermoplastic bending bars. In the present paper, the bending properties of glass fiber reinforced polypropylene (GFRPP) composite bars were investigated by experimental and theoretical methods. A novel bending fixture of GFRPP bars was specifically designed for GFRPP bars to ensure the reliable bending of the bars. Finite element simulation was employed to analyze the stress distribution of GFRPP bars, providing valuable insights into their mechanical behavior. Additionally, a bending strength model was developed based on the material mechanics, offering a theoretical framework for understanding and predicting the bending strength of GFRPP bars. Finally, the bending mechanism of bars was further revealed according to experimental and theoretical findings. The results of the study demonstrated that the specially designed bending fixture was successful in minimizing damage to the bending section of the GFRPP bars, leading to a significant improvement in bending strength retention of up to 43.2 %. Furthermore, the theoretical results and experimental test have a good agreement in terms of stress distribution and failure mode. The maximum strain in the transition zone between the straight section and the bending section of the GFRPP bars was nearly double that of the straight section at the same stress levels. With the increase of bending radius to diameter ratio from 3.0 to 7.0, the tensile strength of GFRPP bending bars increased by ∼7.9 %. The study identified the transition area between the bending section and straight section of GFRPP bars as the most critical failure point. The strength degradation mechanism during the bending were attributed to the shrinkage and torsion of inner fibers owing to the compression caused the local stress concentration, which caused the inner resin matrix to crack and interface debonding of fiber/resin, leading to the premature tensile failure. • The bending fixture can achieve the high bending strength retention up to 43.2 %. • Theoretical and experimental results verified the most unfavorable failure point. • Larger bending radius contributed to the decrease ∼7.9 % of tensile strength. • Fiber distortion and interface debonding led to tensile failure of bending bars. [ABSTRACT FROM AUTHOR]

The construction industry seeks innovative solutions like smart concrete. Traditional concrete faces durability issues, environmental impact, and high rehabilitation costs. To address this, smart concrete combines eco-friendly materials with advanced nano-technology, featuring self-sensing and self-healing properties to detect damage early and autonomously repair cracks. Researchers explore methods to reduce concrete's carbon impact through clinker replacement and alternative binders. The industry moves toward sustainable and technologically advanced practices, where "smart concrete" marks a transformative shift in construction, promising eco-conscious, technology-driven building methods. This review explores smart technology in concrete construction, focusing on structural health monitoring and autonomous crack repair advancements. It consolidates diverse self-sensing and self-healing mechanisms, emphasizing their role in viable construction goals. The paper delves into the impact of nanomaterial on the mechanical and durability of self-sensing, self-healing, and self-adjusting concrete, showcasing smart concrete's potential for transformative construction practices. Biomimetic Structural Health Monitoring (SHM) systems using self-sensing concrete and nanomaterials detect strain changes independently, which is vital for effective monitoring. Real-time Structural Health Monitoring using embedded sensors aids in timely decision-making for asset management and ensures continued structural safety. Self-activated bacteria in concrete provide an eco-friendly solution for crack healing by producing calcium carbonate and reinforcing structural integrity. Bacteria-based agents show promise in enhancing concrete's crack repair potential, aligning with better construction practices. In conclusion, smart concrete presents a significant opportunity to transform the construction sector, emphasizing eco-friendliness, resource optimization, and robust infrastructure. • Smart concrete features self-sensing and self-healing properties to detect damage early. • Researchers are exploring methods to improve the properties of smart concrete through alternative binders. • Structural Health Monitoring (SHM) systems using self-sensing concrete aid in effective monitoring. • Self-activated bacteria in concrete provide a solution for crack healing, enhancing construction practices. [ABSTRACT FROM AUTHOR]

Rock formations naturally contain intricate internal fractures due to various environmental factors. Such fractures result in significant weakening of the mechanical properties of the rock mass. As factures have different geometric features and fill material characteristics, it is difficult to replicate their complex behavior in the laboratory. This poses a serious limitation on the experimental investigation of the mechanical properties of fractured rocks. Sand powder 3D printing (3DP) can overcome the limitations of casting methods in preparing samples with complex fractures and thus is widely applied in soft rock mechanics experiments. This paper utilizes Computer Tomography (CT) scanning to obtain the probability distribution patterns of fractures in fractured rock samples. Additionally, it combines sand powder 3DP technology to generate soft rock-like samples with internal networks of filled fractures. Uniaxial compression experiments employing digital image correlation (DIC) and acoustic emission (AE) techniques are used to investigate the mechanical properties, deformation characteristics, and fracture evolution patterns of samples with different fracture densities. By increasing the fracture density, the peak strength of the soft rock-like samples exponentially decreases, and the deformation characteristics linearly decrease. Crack propagation paths mostly follow the prefabricated fracture trajectories and loading direction. An RA-AF analysis suggests that the failure mode of the soft rock-like samples transitions from diagonal shear failure to block-shaped shear failure with increasing fracture density. These research findings represent a novel sand powder 3DP approach for studying the complex mechanics of complex fractured rocks. • A novel method to generate rock analogs with filled internal fractures is proposed. • Internal fracture density has great effect on the mechanical properties of samples. • Effect of fracture density on failure patterns are investigated with DIC and AE. [ABSTRACT FROM AUTHOR]

The engineering problems caused by dispersive soil are of worldwide concern. Traditional high carbon emission soil amendments such as cement and lime cause several environmental problems, including pollution and soil alkalization. Inorganic polymers are considered to be an economical, effective, and environmentally friendly soil amendment. Therefore, this paper proposes the use of the polymeric coagulant polyaluminum chloride (PAC) to improve soil dispersivity. PAC was added to the dispersive soils at different dry mass ratios of 0%, 0.5%, 1%, 1.5%, 2.5%, 4%, 5%, 6%, 7%, 8%, and 10%. The soil samples were then cured for 1, 4, 7, 14, and 28 days. Soil dispersivity was determined by crumb tests, pinhole tests, and exchangeable sodium ion percentage tests. Soil mechanical strength was assessed through unconfined compressive strength tests and unconsolidated undrained triaxial tests. Particle size distribution, pH, resistivity, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy tests were conducted to investigate soil improvement mechanisms. Experimental results indicate that 1.5% PAC can transform highly dispersive soil into non-dispersive soil after 1 day of curing. When the PAC content increases from 0% to 7%, the unconfined compressive strength of the soil increases by 110.1%, and the internal friction angle and cohesion increase by 61.1% and 24.2%, respectively. The changes in the physicochemical properties and microstructure of the soil indicate the high-valence cations produced by PAC hydrolysis can effectively replace Na+ in the soil, while significantly reducing the pH value of the soil. Simultaneously, the coagulation effect generated markedly reduces soil porosity, resulting in a more compact soil structure. In summary, PAC demonstrates excellent potential in improving soil dispersivity and mechanical properties. Compared to traditional high carbon emission amendments such as cement and lime, PAC can effectively reduce soil alkalinity, mitigate environmental issues associated with these materials, and offer new possibilities for improving dispersive soils. • 1.5% polyaluminum chloride transform dispersive soil into non-dispersive soil. • Polyaluminum chloride increase the strength of the soil by up to 113.19%. • 1.5% polyaluminum chloride reduces exchangeable sodium content in soils. • Intergranular cementation is different for different contents. [ABSTRACT FROM AUTHOR]

Ultrafine cement is widely used in micro-fracture grouting due to its very small particle size, and the expansion agent can improve the dry shrinkage and cracking phenomenon of ultrafine cement grouting materials, and at the same time produce self-stress to enhance the sealing effect, but at present, there are fewer researches on the hydration synergistic effect of ultrafine cement and expansion agent. For this reason, this paper explored the effects of two commonly used expansion agents, U-type and MgO-type, on the mechanical properties, hydration heat, hydration products and microscopic morphology of ultrafine cement materials. The results demonstrated that the expansion performance of MgO-type expansion agent (MEA) was better than that of U-type expansion agent (UEA); At the same time, the MgO-type expansion agent delays the exothermic cement hydration and inhibits the transformation of hydration products, and the stress concentration generated by its delayed expansion effect leads to brittle damage of the material. UEA participates in cement hydration and produces swelling crystals, and at this time, the specimen was mainly cemented in the form of particles, and the pre-generated internal expansion stress densifies the pore structure of ultrafine cement, which enhanced the mechanical strength of the specimen. • The effects of MgO and U-type expansion agent on the expansion and mechanical properties of superfine cement were analyzed. • The effects of U-type and MgO type expansion agent on the microstructure of ultrafine cement grouting materials were analyzed. • The relationship between hydration coordination and properties of superfine cement and expander was revealed. [ABSTRACT FROM AUTHOR]

Microbially induced carbonate precipitation (MICP), an emerging technique recently, has been investigated in extensive studies for its ability to improve or enhance the properties of materials. This paper mainly explored the effect of MICP on the early strength and hydration products in fly ash blended cement paste (FABC) under different MICP treatment measures. Firstly, the influence of different environment on the growth of microorganism and three calcium source (CaCl 2 , Ca(CH 3 COO) 2 and Ca(NO 3) 2) on the production of calcium carbonate precipitation were investigated. The experimental results presented that the efficiency of CaCO 3 precipitation in the Ca(NO 3) 2 sample by adding bacterial solution is higher than other groups. Compared to untreated specimens, the mechanical properties of FABC paste are adversely affected by direct mixing with bacterial solution (MICP1) due to the fact that the hydration reactions of C 3 S and Ca(OH) 2 (CH) in FABC system were negatively affected as indicated by the hydration heat measurement. In contrast, the early performance of drying-immersing sample in bacterial solution (MICP2) was improved, with a maximum efficacy of 52.03%. The hydration process was facilitated in FABC paste treated with MICP2 treatment, further leading to increased formation of CH, C-S-H and AFt. Furthermore, Nanoindentation showed the HD C-S-H gel and CH were the dominant phases in MICP2 samples, and the matrix became denser with more hydration products, which also confirmed the increase in macroscopic compressive strength. The findings of this work can provide a guidance for the application of FA based on MICP method for enhancing the early strength in cementitious materials. • Compared with Ca(CH 3 COO) 2 and CaCl 2 , the efficiency of CaCO 3 precipitation in the Ca(NO 3) 2 sample is highest. • The hydration process of FABC is negatively affected by MICP1 treatment. • The MICP2 treatment can improve the early compressive strength of FA blended cement. • Nanoindentation detects more HD C-S-H gel and fewer porosity percentage. • More hydration products enhance the macroscopic and microscopic mechanical properties. [ABSTRACT FROM AUTHOR]

Mechanical activation is a solution to the problem of low reactivity of ferrous extraction tailing of nickel slag (FETNS). In this paper, FETNS was treated with different ball milling times (5 min, 10 min, 20 min). The effects of mechanical ball milling on the microstructure, mineral phase composition, and particle size distribution of FETNS were analyzed. The effects of mechanical ball milling on the properties, reaction products, and pore structure of the FETNS-OPC composite cementitious system were studied. The experimental results show that mechanical ball milling increases the fineness of FETNS and the amorphous phase content. The compressive strength of the composite cementitious system increases with the increase of ball milling time. The compressive strength of 3d, 7d, 28d, 60d, and 90d increases by 65.96%, 22.3%, 14.97%, 23.43%, and 9.12%, respectively. X-ray diffraction test and simultaneous thermal analysis show that the increase in ball milling time promotes the formation of reaction products. The hydration heat test shows that the increase in ball milling time increases the heat release rate of the early hydration reaction. N 2 adsorption-desorption experiments show that the increase in ball milling time increases the number of fine pores in the slurry, reduces the number of coarse pores, and improves the compactness of the internal structure. Mechanical activation can stimulate the reactivity of FETNS, which is conducive to the application of FETNS in building materials. • The effect of ball milling on the physical properties of FETNS was studied. • The effect of ball milling on the reactivity of FETNS was investigated. • The effect of ball milling on the properties of cementitious system was studied. [ABSTRACT FROM AUTHOR]

Bio-based concrete, which utilizes recycled agricultural waste as aggregates, has emerged as a sustainable alternative material in the construction industry. Optimizing its combined mechanical and thermal performance can promote its environmental and energy benefits. To achieve this, this paper presents a multi-objective optimization approach to improve the overall performance of bio-based concrete based on multiscale structural features, considering the porosity, shape, orientation, and volume fraction. Optimization strategies are provided for three main industrial applications. Furthermore, this study addresses multiple design requirements, including high-volume bio-aggregates, more demanding performance requirements, low densities, and humid environments. The optimization results demonstrate that the optimal solution varies with industrial applications and requirements. Consequently, we quantitatively provide specific optimal solutions for each case, and offer designers three preferences for mechanical properties, insulation, or balanced performance. Overall, this study optimizes the comprehensive performance of bio-based concrete in terms of multiscale structures, thereby contributing to a more sustainable construction industry. • A customized multi-objective optimization approach for bio-based concrete. • Decision variables of shape, porosity, volume fraction, and orientation. • Differences in high-volume bio-aggregates, lightweight roofing, and humid environment. • Three preferences for mechanical performance, insulation, and balanced performance. • Optimal solutions for various industrial applications, requirements, and preferences. [ABSTRACT FROM AUTHOR]

In this paper, the effects of recycled powder content, fly ash content, and different mixing ratios of recycled powder and fly ash on the hydration process of cement were systematically studied by isothermal calorimetry, and the evolution of its mechanical properties was explored. Additionally, a variety of modern analytical testing techniques were used to quantitatively characterize the content of hydration products and the evolution of microstructure. The results showed that the recycled powder can accelerate the early hydration rate, while the fly ash reduces the early hydration heat release rate and delays the hydration process. Both recycled powder and fly ash can reduce the total heat of hydration. The increase of recycled fine powder and fly ash content leads to a decrease in mechanical properties. In the ternary system, when the total substitution rate of recycled powder and fly ash is 30%, and the rate of the two is 1:1, the mechanical properties are optimal; with the increase of the content of recycled powder and fly ash, the content of hydration products of the specimen decreases and the porosity increases. When the ratio of recycled fine powder and fly ash is 1:1, the content of hydration products of the specimen increases, the pore size is refined, and the porosity decreases, which indicates that there is a synergistic effect between recycled fine powder and fly ash. • Research on the hydration process of recycled powder-cement binary system. • Study on the synergistic effect of recycled powder and fly ash in cement-based materials. • The microstructure evolution law of recycled powder in cement-based materials. [ABSTRACT FROM AUTHOR]

Concrete, renowned for its strength and durability, stands as the primary material in infrastructure construction. Despite its extensive use over millennia, its response to fire remains inadequately understood, posing threats to structural resilience and human safety. The consideration of fire resistance becomes paramount in selecting building materials. Throughout their operational lifespan, structures may encounter fire-related risks. Although there is a prevailing belief in the inherent fire resistance of concrete, its performance at high temperatures is subjected to alterations in both physical and chemical properties, impacting its strength and durability. Cracking and spalling may occur, resulting in economic losses and, in severe cases, loss of lives. Moreover, the production of concrete contributes to the depletion of natural resources, causing adverse environmental effects. In the world of building materials, the pursuit of innovative solutions for strength and resilience has been incessant. Consequently, researchers globally recognize the need for an environmentally friendly alternative to concrete. As concerns about fire safety grow, attention has shifted to geopolymer concrete, presenting itself as a promising eco-friendly substitute with significant potential to enhance fire resistance. Geopolymer concrete entirely replaces traditional cement concrete with waste materials rich in Alumina and Silica. Apart from mitigating environmental impacts, it exhibits superior resistance to high temperatures compared to ordinary Portland cement concrete, with the ability to endure temperatures ranging from 1000°C to 1200°C.Enhancements in the high-temperature behavior of geopolymer concrete can be achieved by incorporating materials such as fibers, marble powder, waste glass, rubber crumbs, nanoparticles, etc. This review explores the realm of geopolymer concrete, specifically delving into its fire-resistant properties. It provides a brief overview of the mechanical performance of geopolymer concrete subjected to elevated temperatures and elucidates the role of various materials in enhancing its behavior. It has been seen that in high temperature study of GPC, residual compressive strength is crucial and it mostly rises up to 150°−350°C but declines beyond 400°C due to micro-crack formation. Also, superior tensile strength is shown up to 300°C, with notable decline beyond 800°C. Incorporating fibers in GPC improves these residual properties. Different fibers, such as carbon, glass, basalt, polypropylene, and steel, have specific advantages and considerations. Recycled tire fibers prove cost-effective alternatives improving fire resistance in GPC, with an optimum content of 1.2–2 kg/m3.Usage of rubber particles in GPC prevent spalling at elevated temperatures by allowing water vapor escape, but increased amounts decrease compressive strength, while as using waste glass in GPC enhances microstructure, compressive strength and thermal stability but care is needed to address alkali-aggregate reactions. By comprehending the intrinsic characteristics and performance of geopolymer concrete with suitable additives at high temperatures, this paper aims to highlight its potential to revolutionize fire safety measures within the construction industry. This article not only initiates possibilities for future research on the fire-resistant qualities of geopolymer materials, but it also lays the groundwork for assessing elevated temperatures behavior of Geopolymer Concrete. • Investigation into how elevated temperatures impact the mechanical characteristics of GPC. • Role of aggregates on the performance of GPC at elevated temperature. • Role of various materials and fibers in improving the behavior at elevated temperature. [ABSTRACT FROM AUTHOR]

In this paper, the structural evolution of natural rock asphalt and rock asphalt treated with liquid nitrogen subjected to high temperature and high pressure (HTHP) were studied, and then its influence on mechanical properties of oil well cement was investigated. The results show that the pyrolysis reaction of rock asphalt was promoted by HTHP, which occurred at 320 ℃ at normal pressure and appeared at 180 ℃/20.7 MPa. The pores in the particles caused by the pyrolysis of rock asphalt were healed with the extension of curing time, and the interface bond between rock asphalt and cement matrix was improved. Rock asphalt has a good toughening effect on cement paste, especially treated rock asphalt. • High temperature and high pressure promoted the pyrolysis of rock asphalt. • The rock asphalt treated by liquid nitrogen can enhance the toughness of cement stone under HTHP. • The interface bond between rock asphalt and cement matrix was gradually improved with the extension of curing time. [ABSTRACT FROM AUTHOR]

This paper presents the mechanical behavior of macro-synthetic fiber-reinforced concrete with polypropylene fibers (MSFRC) under varying temperature environments. The Lattice Discrete Particle Model (LDPM), a meso-scale model for concrete, is used for the plain concrete study. An extended version of LDPM taking into account the effect of fibers in a discrete way, LDPM-F, is applied for the MSFRC study. The model is calibrated based on the experimental data at room temperature (20 ° C). Temperature effects on the MSFRC constituents, fiber and concrete, are individually adjusted inside the LDPM-F formulation based on literature data and available models. Subsequently, predictive three point bending simulations on MSFRC are performed at different temperatures (− 30 ° C , − 15 ° C , 0 ° C , 40 ° C and 60 ° C) and the results are validated against available experiments. The results show a generally good agreement between simulations and tests. [Display omitted] • MSFRC behavior is studied under moderate temperature variations (− 30 °C to 60 °C). • Meso-scale models, LDPM is used for plain concrete and LDPM-F is applied for MSFRC. • Temperature models for strengths and moduli of fiber and concrete are applied in LDPM-F. • Fiber–matrix interface micromechanical parameters are adjusted from back analysis. • MSFRC flexural response is reproduced at − 30 °C, − 15 °C, 0 °C, 40 °C, and 60 °C. [ABSTRACT FROM AUTHOR]

Bamboo structures are susceptible to natural weathering when exposed to outdoor conditions, making it imperative to comprehend the aging resistance of bamboo. In this paper, the study of Moso bamboo exposed to outdoor environment for one year illustrates the discoloration, expansion, mass loss and density reduction of the specimens. The changes of relative crystallinity (CrI) of bamboo were measured by using X-ray diffraction (XRD), the microstructural changes of bamboo were observed by scanning electron microscopy (SEM), and the computed tomography (CT) scanning technology was used to analyze the internal structure of the damaged specimens. Meanwhile, the damage and differences in the mechanical properties of bamboo internodes and nodes were evaluated by the tests of compression parallel to the grain, compression perpendicular to the grain and compressive elastic modulus parallel to the grain, taking into account the bamboo height. The results showed that natural weathering reduces cellulose crystallinity and has a detrimental effect on the cellular structure of bamboo, resulting in a weakening of the interfacial bonding between the vascular bundles and the parenchyma. Consequently, this leads to a decrease in the mechanical properties of bamboo. Compared to the internode specimens, the compressive strength perpendicular to the grain and compressive elastic modulus parallel to the grain are higher in the bamboo node specimens. However, the compressive strength parallel to the grain will be significantly reduced due to the complex fiber structure inside the bamboo nodes. In light of the experimental findings, a constitutive model is proposed to describe the relationship between uniaxial compressive stress and strain in Moso bamboo, both before and after weathering. The numerical results obtained from this model demonstrate a strong correlation with the experimental findings, thereby establishing a solid foundation for conducting finite element analysis on Moso bamboo structures. • The cellulose crystallinity and microstructural changes of weathered bamboo were analyzed. • Comparative studies were conducted to investigate the mechanical properties of weathered bamboo. • An axial compressive stress-strain constitutive model of weathered bamboo was proposed. [ABSTRACT FROM AUTHOR]

In this paper, a high and low-temperature cementitious composite incorporating phase change material (PCM) was developed by using n-tetradecane (C14) and F46 paraffin (PA) as PCMs and expanded perlite (EP) as a carrier. The thermal properties and stability of the PCM-incorporated cementitious composites were studied by high and low-temperature cyclic tests. Phase change cement-based materials (PCESMs) were characterized by thermal conductivity testing, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). FT-IR results and SEM imaging showed that C14 and PA could effectively fill EP pores, and there was no chemical reaction between C14, PA, and EP. DSC confirmed that the composites incorporated with PCMs wrapped by the direct encapsulation method still maintained a high latent heat. The experimental results also showed decreasing mechanical properties (compressive and flexural strength) of PCESM with increased PCM dosage, whereas the corresponding thermal performance gradually increased. 20% PCM content was found optimal for the overall performance of PCESM. • A novel thermal insulating composite is prepared using PCMs. • Properties of high and low-temperature cement-based PCMs are studied. • Mechanism of the developed composites is studied by microscopic analysis. • High and low-temperature cyclic tests corroborated the better performance of PCMs. • The optimal dosage of PCMs in cementitious composite is also determined. [ABSTRACT FROM AUTHOR]

In order to explore the influence of initial strain on the photo-oxidation aging process of HDPE sheath, the actual strain value of HDPE sheath was calculated based on the design method and the production process of parallel steel wire suspender. The initial strain of HDPE specimen was applied by fixture, and xenon arc lamp accelerated aging test of HDPE were carried out. The results show that after 5000 h xenon arc lamp accelerated aging, the tensile strength, yield strength and secant modulus of the elastic stage of the specimen decrease by 11.19%, 9.15% and 40% respectively. During the aging process, there is no obvious increase or decrease in the elongation at break.There is a critical time in the aging process, when the aging time exceeds the critical time, the yield elongation of HDPE specimen will increase sharply; When the aging time is less than the critical time, the tensile properties of the specimens are basically unchanged with the increase of the initial strain; When the aging time is greater than the critical time, with the increase of initial strain, the tensile strength of the specimen decreases gradually, while the yield strength and secant modulus increase gradually. The critical time increases with the increase of initial strain. In addition, based on the experimental results, the prediction model of HDPE strength and secant modulus is established. The results of this paper lay a foundation for the prediction of the remaining service life of HDPE sheath, which can provide a theoretical basis for the durability design of suspension bridge cable system. • The tensile properties of HDPE sheath for parallel wire suspender after photo-oxidative aging is explored. • The characteristics of elastic stage, strain softening stage, necking stage and orientation hardening stage are analyzed. • With the increase of aging time, the tensile and yield strength and secant modulus in the elastic stage decrease. • When the aging time exceeds a critical time, the yield elongation of the specimen suddenly rises. [ABSTRACT FROM AUTHOR]

Backfill mining is an effective technique that can prevent and control the impact of dynamic disasters which can occur in deep underground coal mines. This technique allows to reduce the surface subsidence and achieve a greener mining. The backfill shear mechanical properties under mining disturbances, are of great significance for ensuring the surrounding rock stability in deep mining. Therefore, studying the shear mechanical properties of the cemented gangue backfill body (CGBB) under coupled dynamic and static loads actions in deep coal mining is of great importance. In this paper, shear mechanical tests and the acoustic emission (AE) technology were used to study the shear mechanical response characteristics of CGBB under low-frequency dynamic normal load conditions. The results show that a dynamic normal load with an amplitude of 5 kN improves the shear CGBB strength, while a dynamic load with an amplitude greater than 10 kN will cause a shear strength deterioration, and the degree of deterioration is positively correlated with the load amplitude. Under low-frequency dynamic normal load conditions, the shear CGBB stress-strain curve exhibits classical characteristics. AE indicate that the main CGBB damage changes from a nonlinear deformation to an elastic stage under low-frequency dynamic normal load conditions. During the shear failure process, the cumulative AE counts are positively correlated with the load amplitude. The crack type identification based on RA-AF shows that the low-frequency dynamic normal load affects the CGBB crack type. Under constant normal load (CNL) conditions, tensile or mixed cracks account for 63.95% and are the main fracture mode. Conversely, under low-frequency dynamic normal load conditions, shear cracks account for more than 60% and are the main failure mode. This research provides a reference for the CGBB stability analysis under complex stress conditions for the case of a deep underground coal mining. • The effect of dynamic normal load on the shear mechanical properties of cemented gangue backfill body was studied. • The impact mechanism of dynamic normal load on CGBB was studied through acoustic emission technology. • Based on RA-AF, the effect of dynamic normal load on the type of CGBB cracks was investigated. [ABSTRACT FROM AUTHOR]

This study delves into the influence of various nanomaterials on the mechanical performance and durability of sludge-based geopolymer. In terms of overall strength, it was evident that nanosilica (NS), when introduced at the same doping level, exhibited the most significant enhancement in mechanical properties, surpassing nano-calcium carbonate (NCC) and graphene nanoparticles (GNPs). For instance, the addition of 2% NS resulted in a remarkable increase of up to 108.2% in compressive strength and 69.9% in flexural strength. Furthermore, the early reaction rate of sludge-based geopolymers was positively affected by the incorporation of NS, NCC, and GNPs. After 28 days, thermogravimetric analysis demonstrated that the mass loss for the reference sample and geopolymers enhanced with NS, NCC, and GNPs was approximately 15.06%, 14.78%, 14.85%, and 14.95%, respectively. Regarding durability, the sludge-based geopolymers displayed enhanced resistance to sulfate erosion and freeze-thaw cycles. This improvement was attributed to the ability of nanomaterials to fill pores and promote hydration reactions, resulting in a denser matrix. This paper delves into the influence of nanomaterials on the gel microstructure and gel micromechanical properties, shedding light on the mechanisms responsible for the enhanced mechanical and durability properties. It also presents a comparative analysis of results at different doping levels, offering a promising solution for waste treatment and carbon emission reduction, while making a compelling case for practical engineering applications. • First study of mechanical and durability properties of nanomodified sludge-based geopolymers. • Nanomodified sludge-based geopolymers can be used for practical engineering applications. • The mechanical properties of nanomodified sludge-based geopolymers depend on factors such as gel strength, pore filling and chemical bonding. [ABSTRACT FROM AUTHOR]

In this paper, an experimental study on mechanical properties at high temperature of a typical autoclaved aerated concrete (AAC) tested in compression is presented (compressive strength = 5 MPa and density = 600 kg/m3 at 20 °C). Parameters such as the compressive strength, strain at the peak stress, and elastic modulus are investigated, along with the stress-strain response in the thermal range 20–700 °C. The behavior of the AAC tested in this research project is different from that of normal concrete, because of a series of chemo-physical processes occurring at high temperature. Between 100 and 600 °C, the compressive strength increases and then starts decreasing (+51% at 600 °C and +10% at 700 °C compared to ambient conditions). The strain at the peak stress increases as well with the temperature similar to – but more than in – normal concrete. The stress-strain curves and the failure modes show that AAC's behavior is brittle at any temperature and that the damage inside the material increases with the temperature in such a way that the existing models for normal concrete exposed to high temperatures cannot be used in the case of AACs. Hence, a new polynomial model is proposed to properly describe the constitutive behavior of AACs at high temperature. • Experimental study on compressive propertiesof a typical autoclaved aerated concrete (AAC) at high temperature. • Compressive strength, strain at peak stress, elastic modulus, and stress-strain response are studied between 20-700 °C. • Compressive strength increases between 100-600 °C and then decreases. Strain at peak stress increases with temperature. • Failure mode is brittle. A polynomial model is proposed to describe the constitutive behavior of AACs at high temperature. [ABSTRACT FROM AUTHOR]

This paper studied the effects of microwave power and time on microstructure and mechanical properties of Ultra-High Performance Geopolymer Concrete (UHPGC) matrix. Results show that conducting microwave treatment at curing age of 3d is suitable, the optimal microwave power and time are 560 W and 180 s with the 3d compressive strength and flexural strength of 125.4 MPa and 6.0 MPa. The large amount of heat generates in UHPGC matrix under microwave field, which leads to the increase in temperature within the UHPGC matrix. Due to hydration promotion caused by internal temperature rise, the tighter gels accumulation and lower porosity can be observed, which results in the remarkable improvement of compressive strength. However, microwave heating causes higher proportion of large pores and more generation of "melon seed flake" hybrid crosslinking products mainly including N-A-S-H, which will result in the reduction of flexural strength. Moreover, microwave pre-curing is more suitable for preparing UHPGC compared with the oven pre-curing comprehensively considering the early age compressive strength enhancement and energy consumption. • Microwave pre-curing parameters for preparing UHPGC were optimized. • Mechanical properties evolution laws after microwave pre-cured were acquired. • Microstructure evolution mechanism during microwave pre-cured was revealed. [ABSTRACT FROM AUTHOR]

Fly ash is known as a common geopolymer precursor. However, it is important to search for suitable alternatives as the availability of fly ash will reduce with the move to more renewable energies. This paper evaluates the feasibility of using waste clay brick powder (WCBP) as a partial alternative for fly ash in geopolymer mortars with ground granulated blast furnace slag (GGBFS), under ambient and heat curing conditions. The physical, mechanical, and mineralogical properties of geopolymer mortar with 10 to 40% WCBP were investigated. Microstructural properties of WCBP and geopolymer mortars were investigated using X-ray fluorescence (XRF), X-ray diffraction (XRD), tescan integrated mineral analyzer (TIMA), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). Reductions of the flow of fresh mortar were observed with the increase of WCBP. The highest 28 days compressive strengths were obtained in the mortars containing 40% WCBP, both at ambient and heat curing conditions. Microstructural analysis highlighted compact structure and reduced porosity, which are attributed to the role of WCBP in enhancing fly ash-GGBFS mortar properties by promoting geopolymer gel formation. • Characterization of Waste Clay Brick Powder (WCBP) showed its potential use as a geopolymer precursor. • The effect of WCBP on the mechanical and mineralogical properties of fly ash-GGBFS-WCBP geopolymer mortar was investigated. • High strength and a compact microstructure development could be achieved by using up to 40% WCBP. [ABSTRACT FROM AUTHOR]

Fly ash collected from the flue of a power plant's circulating fluidized bed furnace is referred to as circulating fluidized bed (CFB) fly ash. The high pozzolanic activity of CFB fly ash has potential benefits for the production of environmentally friendly building materials. To actualize the sustainable and large-scale utilization of CFB fly ash in the field of building materials, this paper reviews the pertinent domestic and international literature and introduces the fundamental characteristics of CFB fly ash, including its phase composition and chemical composition. In terms of fresh mixing properties, mechanical properties, and durability, the research advancement of CFB fly ash-based cementitious materials (CFBFACM) was reviewed. Particularly, the influence of unstable factors f-CaO and SO 3 in CFB fly ash on the various properties of ecological building materials is examined, because, in the early stage, f-CaO and SO 3 will react to promote the dissolution of active silicon and aluminum and generate hydration products that are conducive to the development of strength. The internal tension is insufficient to withstand the crystallization pressure as gypsum and ettringite become increasingly abundant. Consequently, macro strength loss and inadequate durability are brought about. By calculating the ratio between the elements of AFt and C-(A)-S-H gel, CFBFACM with high strength, good volume stability, and good durability can be designed. In addition, in the collaborative treatment of multi-component solid waste, full consideration of bulk density and particle size distribution is beneficial to the performance of CFBFACM. The method of adding nanomaterials or modifying CFB fly ash may become the way of large-scale utilization of CFB fly ash. In the future, it is still necessary to evaluate the cost and sustainability of the life cycle of CFBFACM to fully understand the economic value, ecological value, and social value of the large-scale utilization of CFB fly ash. • Particle size and packing density affect the rheology properties of CFBFACM. • CFBFACM with well mechanical properties can be prepared by designing element ratio. • The content of f-CaO and SO 3 affect the volume stability of CFBFACM. • The cementitious material based on CFBFA has good durability. [ABSTRACT FROM AUTHOR]

The mechanical performance of carbon fiber reinforced polymer (CFRP) is a crucial parameter influencing the effectiveness of CFRP reinforcement. The addition of nano-toughening agents to the resin matrix can effectively enhance the mechanical properties of CFRP. This paper investigates the influence of nano-SiO 2 and MWCNTs content (0.2, 0.4, and 0.6 wt%) as well as their blending ratios (1:3, 1:1, 3:1) on the tensile properties of CFRP plates using the vacuum assisted resin infusion molding (VARIM) process. Additionally, an assessment is conducted to evaluate how the tensile performance of CFRP plates affects the CFRP plate/steel interface performance.The results indicate that the resin viscosity increases with the addition of nano-toughening agents, with the resin viscosity experiencing a respective increase of 32.9% and 92.7% when incorporating 0.6 wt% nano-SiO 2 or MWCNTs compared to pure resin. The inclusion of nano-toughening agents enhances the tensile strength of CFRP plates, with a more pronounced effect observed when adding 0.4 wt% nano-SiO 2 or MWCNTs, resulting in respective increases of 41.5% and 31.5% compared to pure CFRP plates. When nano-SiO 2 and MWCNTs are mixed, the tensile performance of the CFRP plate is inferior to that of plates with the same individual nano-toughening agents content. This is attributed to the excessively high viscosity of the resin matrix during mixing, hindering complete infiltration of carbon fibers. Therefore, in the manufacturing process of CFRP plates using the VARIM technique, it is advisable to consider resins with lower viscosity. Additionally, the utilization of CFRP plates with superior tensile performance contributes to enhanced CFRP/steel interface properties, although the tensile performance of CFRP plates does not alter the bonding slip curve of CFRP/steel double-lap joint specimens. • Effect of nano-toughening agent content on composites. • Synergistic effect of nano-SiO 2 with MWCNTs. • Influence of CFRP plate properties on CFRP/steel interface properties. [ABSTRACT FROM AUTHOR]

This study investigated different properties of foam-type composites made from recycled cardboard. Two types of panels, type A (237.36 kg/m3) and type B (284.28 kg/m3) were manufactured varying the share of corn starch as binder. Dimensional stability to water, vertical density profile (VDP), thermal conductivity, bending characteristics, and internal bond strength tests were conducted. The results revealed that the higher corn starch content improved the modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond strength (IB) by 56%, 33%, and 30% for panel type B, respectively. However, no significant difference was observed for the internal bonding strength test. Statistical analysis revealed that no substantial difference in the thermal conductivity property of the two types of panels was determined at a 95% confidence level. The water absorption and thickness swelling increased for both samples after 24 h water immersion. Foam-type panels made from waste cardboard would have the potential to be used for certain applications such as insulation purposes within the perspective of sustainability and a green approach. [Display omitted] • Efficient insulation of buildings is a significant contributor to overall global energy consumption. • Recycling cardboard into new value-added products comprehends its life cycle. • Foam composites were manufactured using cardboard, corn starch, and sodium bicarbonate mixture. • Thermal insulation is a potential application of developed cardboard foam-type composites. [ABSTRACT FROM AUTHOR]

Due to high Cl- content and porosity in coral, coral-aggregate concretes usually present poor durability and mechanical properties. In this paper, two types of materials, polyvinyl alcohol (PVA) and Calcium Sulphoaluminate (CSA) clinker, were used to modify properties of coral sand and consequently inhibit leaching of Cl- from coral and improve mechanical properties of yield mortar. Results showed that the smaller the particle size, the greater Cl- dissolution rate of crushed coral sand. PVA and CSA materials could effectively inhibit the Cl- dissolution, and the most obvious decrease could reach 6% and 23%, respectively, in comparison of 35% prior to the modifications. However, mechanical properties of these two modified coral sand mortars were unsatisfactory under standard curing, which the CSA-modified specimens generate thaumasite resulting in a strength decrease and could be improved by a slight increase in curing temperature to 35 ℃. • PVA and CSA were used to improve mechanical and chloride dissolution of crushed coral sand. • PVA decreases number of pores for entire diameter, CSA divided bigger pores into smaller ones. • Both the PVA and CSA modifications inhibit dissolution of Cl from coral sand. • CSA modified coral sand mortar needs a higher curing temperature for satisfactory strength. [ABSTRACT FROM AUTHOR]

The low-temperature mechanical properties of aluminium alloys (AAs) are important for the analysis and design of infrastructures in cold regions and LNG storage tanks made of AAs. This paper investigated the stress-strain behaviours of AA 5083-H112/6061-T6 materials through conducting tensile tests on 32 AA coupons at 20 ℃ ∼ −165 ℃. All the tested AA coupons exhibited ductile failure modes. Their results showed that the stress-strain curves of AA 5083-H112 exhibited the Portevin-Le Chatelier effects that gradually weakened with the decreasing temperature. Reducing the temperature from 20 ℃ to −165 ℃ increased the elastic modulus, yield and ultimate strengths of AA 5083-H112 (or 6061-T6) by 5.1% (6.5%), 8.7% (12.0%) and 7.8% (13.1%), but reduced the fracture strain by 16.4% (12.4%). The fracture surfaces of all AA 5083-H112 and 6061-T6 coupons displayed localised cross-sectional area reductions and substantial plastic deformation. Meanwhile, precipitation-hardened AA 6061-T6 exhibits a more pronounced enhancement compared to strain-hardened AA 5083-H112. Furthermore, regression analyses were performed to establish prediction equations for the low-temperature mechanical indexes of AAs. Subsequently, a full-range constitutive model was proposed to estimate the stress-strain behaviours of AA 5083-H112 and 6061-T6. Validations against reported experimental observations demonstrated that the developed model reasonably described the stress-strain responses of AA 5083-H112 and 6061-T6 from 20 ℃ to −165 ℃. • The yield/ultimate strength of AA increases as the T decreases from 20 to −165 ℃. • The AA 5083-H112/6061-T6 coupons fail in ductile modes at low temperatures. • The low temperatures do not compromise the ductility of AAs. • Proposed models predict well the low-temperature σ - ε curves of AA 5083-H112 and 6061-T6. [ABSTRACT FROM AUTHOR]

The optimization of mechanical properties and regulation in setting time of beta-hemihydrate phosphogypsum (β-HPG) are the key to its utilization in building materials. Calcium sulfoaluminate cement (SAC) can significantly enhance the mechanical properties of β-HPG to form a gypsum-based-composite binder, but have little effect on regulating the setting time. Retarders can regulate the setting time of β-HPG but decrease its mechanical properties. However, the synergistic modification mechanism of retarders and SAC on β-HPG has not been clarified. In this paper, the effects of protein retarder (SC) and citric acid (CA) on the setting time, hydration heat, mechanical properties and microstructure of the β-HPG-SAC composite binder were studied systematically. The results show that incorporating SC and CA can effectively regulate the setting time, but the effects on the mechanical properties differ. SC has a certain optimization effect on mechanical properties at low content, but has a negative effect when the content is over 0.2%, while CA has a continuous negative effect with its increasing content. Specifically, SC hinders the formation of the crystalline structure to a certain extent, and makes the crystallization of β-HPG and the hydration of SAC synergistic, while CA delays the hydration process of β-HPG and SAC simultaneously. Different from SC, CA can inhibit the growth of dihydrate gypsum (DH) crystals in the C-axis direction, transforming long rod crystals into short columns, eventually forming a looser microstructure and decreasing mechanical properties. This work provides an effective method for the modification of β-HPG and the high value-added resource utilization of PG. • SC and CA can effectively regulate the setting time of the composite. • SC has a certain optimization effect on mechanical properties at low content. • The contents of AFt are decreased by the incorporation of retarders. [ABSTRACT FROM AUTHOR]

Ultra-high-performance concrete (UHPC) made of limestone calcined clay cement (LC3) exhibits excellent mechanical properties as well as good environmental friendliness. This paper studied the improving effect of nano-SiO 2 on the mechanical properties and microstructure of LC3-UHPC. The experimental results show that the addition of nano-SiO 2 demonstrates obvious advantages. The mechanical properties of LC3-UHPC are enhanced, and the frictional bond performance between steel fiber and cementitious matrix is also improved. The fiber/matrix bond strength is increased. A constitutive model describing the single fiber pullout behavior is established, and the values of related parameters are suggested. Besides, nano-SiO 2 also refined the cementitious microstructure of UHPC and made the matrix denser. Based on the comprehensive analysis of mechanical properties and microstructural characteristics, the optimal content of LC3 and nano-SiO 2 were proposed. [Display omitted] • The performance of LC3-UHPC was improved by using nano-SiO 2. • The microstructure of UHPC using nano-SiO 2 was optimized. • The fiber/matrix bonding behavior of LC3-UHPC was improved. • Comprehensive evaluation of the influence of nano-SiO 2 was conducted. [ABSTRACT FROM AUTHOR]

Roller compacted concrete (RCC) often remains in a damage state as a result of improper vibrating compaction control, which makes it more susceptible to the action of freeze thaw (FT) cycles in cold regions and thus results in the degradation of mechanical behaviors. In this paper, the influences of initial damage and FT cycles on the physical and mechanical behaviors of RCC were systematically examined through physical tests, including FT cycle tests, pore structure tests and uniaxial compressive tests. An in situ vibrating compaction procedure was employed in the experiment to accurately replicate the field compaction process for RCC under laboratory conditions, and the dynamic elasticity modulus (DEM) was adopted as the non-destructive testing (NDT) index to quantify the initial damage caused by improper RCC construction control. The results indicated that the higher values of initial damage and FT cycles exhibited a greater influence on the frost resistance and pore structure distribution. Remarkable attenuation of compressive strength and elastic modulus and an increase in peak strain were observed to occur in RCC when the initial damage degree exceeded 0.1 and the number of FT cycles exceeded 75. Finally, the uniaxial compressive stress strain model was established through segmented linear regression analysis based on the Weibull-Lognormal model. The proposed model was validated to be effective and reasonable in predicting the mechanical properties of RCC under the combined effects of initial damage and FT cycles. • In-situ vibrating compaction method was used to simulate field-compaction process. • Initial damage from improper construction control was quantified by NDT methods. • Effects of initial damage and FT cycles on RCC properties were investigated. • Uniaxial compressive constitutive model for DRCC under FT cycles was established. [ABSTRACT FROM AUTHOR]

To address the deficiencies in traditional communication towers in mobile communication engineering, such as heavy weight, easy corrosion and poor durability, this study proposes replacing traditional communication towers with GFRP communication lattice towers with lightweight, high-strength and good durability. Firstly, GFRP material test and GFRP circle tube bending capacity test are conducted. The maximum bending moment that can be subjected to the anchorage end of GFRP circular tube is 18.20 kN·m. Finite element analysis of GFRP circular tubes verifies the accuracy of the bending test results. Secondly, a GFRP communication lattice tower with a height of 25 m is designed adopting GFRP circular tubes as tower columns. Through the bending test of the GFRP tower, it is verified that the connection between the columns and web members of the GFRP tower is reliable and the force pattern of the GFRP tower is reasonable. The large deflection theory can be adopted to the displacement of GFRP towers accurately. Thirdly, according to the actual engineering requirements, the finite element analysis of 25 m-high GFRP tower under the basic wind pressure of 0.45 kN/m2 is carried out by using 3D3S (a spatial structure design software). It can be obtained that the vibration mode of the GFRP communication tower shows two forms of lateral bending and axial torsion. 0° wind load direction has the greatest influence on the displacement of the GFRP tower. The stress ratio of each component in the GFRP tower is less than 1, indicating that no damage occurs in the GFRP tower. Finally, GFRP towers have good economic benefits, good environmental performance and wide range of application after comparing the GFRP tower and traditional steel tower. The demonstration project of the GFRP communication lattice tower is established in Qingyuan City, Guangdong Province, China. When subjected to a typhoon with a wind speed of 17.26 m/s, The horizontal displacement of the GFRP tower top is 10 m, which is about 2/5 of the height of GFRP tower. Although the displacement is large, the GFRP tower is still not destroyed. It can be concluded from the research in this paper that GFRP towers have low cost, good mechanical properties, good durability, and wide application range, which can promote the rapid construction of 5 G communication base stations. [Display omitted] • The bending moment of the GFRP tube can reach 18.20 kN·m. The finite element analysis match well with bending test. • A 25-m-high GFRP lattice tower is designed. The deformation of GFRP tower can be calculated by large deflection theory. • The vibration mode of the GFRP tower shows two deformation forms: lateral bending and axial torsion around the z-axis. • The GFRP tower has a large displacement but no damage, when subjected wind with the speed of 17.26 m/s. • Applying GFRP tower can effectively improve the construction efficiency of 5 G communication base station. [ABSTRACT FROM AUTHOR]