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Translation abstract High performance aerogel concrete – flexural behaviour with GFRP reinforcementHigh Performance Aerogel Concrete (HPAC) is a new type of structural lightweight concrete based on a combination of lightweight aggregates made from silica aerogels and HPC matrices. To produce HPAC components subjected to bending, as with normal weight and other structural lightweight concretes, internal reinforcement is required on the bending tension side. For reasons of building physics and durability, reinforcement made of fibre‐reinforced plastics (FRP), such as GFRP reinforcement, should preferably be used for this purpose. To investigate the bending behaviour of FRP‐reinforced HPAC components, 16 four‐point bending tests were carried out on HPAC beams of different strengths and with different amounts of reinforcement. For a better understanding of the failure mechanisms, physically non‐linear finite element simulations were carried out and validated based on the test results. The results of the experimental and numerical investigations were used to derive a model for the bending design of FRP‐reinforced HPAC components. This work on the bending behaviour of HPAC components with FRP reinforcement is presented below. [ABSTRACT FROM AUTHOR]

Lightweight concrete, particularly polystyrene concrete, has been extensively utilized in civil engineering for decades. The incorporation of waste expanded polystyrene (EPS) as a filler material in the production of lightweight concrete presents significant advantages from a circular economy perspective. Prior research indicates that increasing the proportion of lightweight aggregates, such as EPS, typically results in reductions in strength and bulk density. The utilization of substantial amounts of EPS waste in the formulation of structural polystyrene concrete is crucial for advancing sustainable construction practices. This study investigates the effects of varying nano-silica content on the bulk density, compressive strength, flexural strength, splitting tensile strength, and water penetration depth of structural polystyrene concrete. Concrete specimens were prepared by substituting 25%, 50%, 75%, and 100% of sand with EPS waste, while evaluating nano-silica contents of 0.75%, 1%, and 1.25%. The findings reveal that increasing the volume fraction of EPS corresponds to a decrease in the concrete's bulk density. This research provides critical insights into optimizing structural lightweight concrete, thereby promoting advancements in sustainable construction applications. [ABSTRACT FROM AUTHOR]

Additive flow production of lightweight precision concrete elements In modern flow production, the focus is on the continuously digitally controlled tools in the context of the digital twin. Spray extrusion, especially when combined with a thin layer of shotcrete and ribbed support structures, e. g. for façade elements, results in highly efficient components with high load‐bearing capacity and high‐quality surfaces. The developed combined spray extrusion nozzle offers the possibility of both spraying and extrusion, adaption of mortar and concrete. In addition, the automated integration of anchors is the focus of flow production, for which anchors and tooling systems have been developed. Based on the determination of characteristic values, the practicability and the increase in productivity will be proven. This data will form the basis of a digital twin, in preparation for Industry 4.0. This increase in productivity in additive manufacturing leads to positive economic effects. Applications of high‐strength lightweight structures in the construction industry are becoming more attractive and enable the serial implementation of free‐form modular constructions. [ABSTRACT FROM AUTHOR]

Nowadays, cold-formed steel (CFS) has become widely used in the field of lightweight structures. In 2016, the Budapest University of Technology and Economics initiated a research study on a unique structural system using CFS and utilized ultra-lightweight concrete as an encasing material. This material serves as continuous bracing that improves CFS element resistance, stability behavior and performance, while also manifesting heat insulation capabilities, thus helping achieve sustainability goals. This paper is considered a continuation of previous research conducted by the authors. An experimental investigation was carried out on encased CFS columns subjected to eccentric loading. A total of fourteen stub-columns, with two distinct thicknesses, were subjected to various loading conditions for testing. The test results showed that local failure controlled the behavior of all the tested elements. The reduction in capacity resulting from eccentricity with respect to centric resistance varied between 20% and 52%, depending on the load position applied and on the core thickness of the tested steel elements. Moreover, the test outcomes were compared to the Eurocode analytical solution of pure steel elements. The overall load increment ranged from 46% to 18%, with a more noticeable bracing impact observed in the case of slender elements. Material tests also supplement the results. [ABSTRACT FROM AUTHOR]

Lightweight geopolymer has good physical and mechanical properties, thermal and chemical stability and low carbon dioxide emissions. The development of high-strength lightweight geopolymer concrete (LGC) for load-bearing structures can expand geopolymer applications. The use of ground granulated blast-furnace slag (GGBFS) to improve the mechanical properties and pore structure of LGC was investigated. The ultimate compressive stress of LGC containing GGBFS were analysed, as well as the variation in microscopic pore structure. Specimens of LGCs with different strengths (LC20, LC30 and LC40) were investigated. As the GGBFS content increases, the ultimate compressive stress and specific strength of LGC increases, while the strain corresponding to the peak stress decreases, indicating that the mechanical properties and deformation resistance of LGC are improved. The carbon dioxide emissions of LGC are less than those of cement-based lightweight concrete, indicating that LGC has good sustainability. Moreover, the addition of GGBFS can produce more gel and reduce the volume proportion of capillary pores and air pores, resulting in LGC densification. Recommended GGBFS contents for strength grades LC20, LC30 and LC40 are 0–12.7%, 12.7–24.6% and 24.6–30%, respectively. The LGC is lightweight and has high strength, and has potential for application in civil engineering. [ABSTRACT FROM AUTHOR]

Iron tailing porous concrete (ITPC) is a type of foamed concrete material that uses iron ore tailings powder to partially replace cement. As a relatively new concrete-like material, only very limited research on the dynamic material property of ITPC under high strain rates has been performed. To supplement the material properties for its practical applications, in this study, splitting Hopkinson pressure bar (SHPB) tests were carried out to measure the dynamic properties of ITPC specimens with a density range of 600 kg/m3–1,200 kg/m3 in a strain rate range of about 120 s−1–250 s−1. The influences of strain rate and density on the impact resistance performance of ITPC were analyzed based on the failure modes, stress–strain relations, compressive strengths, elastic moduli, peak strains, and dynamic increase factors (DIFs). The microstructures of ITPC after impact were also observed and characterized by scanning electron microscopy (SEM). Moreover, the energy dissipation characteristics were discussed and analyzed. The test results indicate that the dynamic properties of ITPC exhibit significant strain rate effects and density dependence. The dynamic compressive strength of ITPC increases quadratically and linearly with density and strain rate, respectively. Moreover, the empirical formulas for dynamic compressive strength, DIF, energy dissipation ratio, and energy dissipation capacity of ITPC as functions of strain rate and material density are proposed based on the experimental data; the variation trends of these key dynamic mechanical parameters of ITPC are analyzed and discussed in detail. [ABSTRACT FROM AUTHOR]

Dynamic cone penetrometer (DCP) has been commonly used for the evaluation and quality control/assurance of soils before, during, and after construction in civil engineering projects. This test equipment has been increasingly used for geotechnical engineering applications but not yet been used to evaluate lightweight cellular concrete (LCC) as a backfill material. This technical note reports laboratory and field DCP tests to evaluate the properties of LCC. To establish the relationship between DCP data and other material properties, unconfined compressive strength and California bearing ratio (CBR) tests were conducted on this material. The test results showed that the measured unconfined compressive strength and CBR of LCC increased as its density increased. The DCP indices (DCPI) for the LCC specimens at different densities were almost constant with the penetration depth. This technical note proposes the correlations between the DCPI and the unconfined compressive strength and CBR, which may be used for future applications. [ABSTRACT FROM AUTHOR]

Pervious concrete (PC) has become more popular in recent years as a solution to the runoff problem. PC has a large number of voids, allowing surface water to flow freely through its structure. Strength and permeability are crucial design factors for PC, but there has been limited research examining their mutual relationship. In the studies, constant head (CH) and falling head (FH) permeability test methods were used to find the coefficient of permeability of the PC because there is no standard method for measuring it correctly and precisely in laboratory conditions. Also, the experiment aims to investigate the influence of various aggregate grading (single, two, and three particle size gradations) and cement-to-aggregate (C/A) ratios (0.20, 0.25, and 0.33) on the compressive strength (CS), split tensile strength (STS), flexural strength (FS), permeability, and porosity of PC while maintaining a constant water-to-cement (W/C) ratio of 0.34. The findings demonstrate that three particle size gradation mixes give higher CS, STS, and FS as compared to single and two particle size gradations. The porosity–permeability relationship of PC was analyzed using experimental results, and the FH and CH permeability tests were compared to determine the more reliable method. The investigation also established a novel model between the CH and FH methods, while examining the correlation between porosity and permeability. [ABSTRACT FROM AUTHOR]

In this study, the combined effects of Expired Cement (EC) fly ash lightweight aggregate (ECFLA), silica fume (SF), and fly ash (FA) were utilized as sustainable alternatives for self-consolidating lightweight concrete (SCLC). The ECFLA was produced by a cold bonding pelletization process using 20% EC and 80% FA mixed by weight in a tilted pan and moisturized with water. A total of 12 mixtures were prepared in four groups; the control group the natural aggregate was replaced with partial and full ECFLA coarse aggregates at 0%, 50%, and 100% levels. Also, 20% FA, in the second group and 10% SF third group were in a binary blend replacement of cement, the fourth group, ternary blend was used with the mentioned admixtures. The mechanical properties of SCLC, including compressive, flexural, and splitting strengths as well as elastic modulus, were evaluated. Furthermore, the drying shrinkage behavior of the mixtures was monitored over a 90-day drying period. The results revealed that the density of structural lightweight concrete reached 1830 kg/m³ with full replacement of normal concrete with ECFLA. Moreover, the compressive strength indicated a decrease of approximately 16.3% and 23% with 50% and 100% replacement of ECFLA, respectively than the reference mixture with normal aggregate at 28 days. However, the negative effects of ECFLA in SCLC can be improved with binary and ternary mineral admixtures. [ABSTRACT FROM AUTHOR]

Structural lightweight concrete (SLWC) is crucial for reducing building weight, reducing structural loads, and enhancing energy efficiency through lower thermal conductivity. This study explores the effects of incorporating silica fume (SF), micro-polypropylene (micro-PP), and macro-PP fibers on the workability, thermal properties, and strength of SLWC. SF was added to all mixtures, substituting 10% of the Portland cement (PC), except for the control mixture. Macro-PP fibers were introduced alone or in combination with micro-PP fibers at volumetric ratios of 0.3% and 0.6%. The study evaluated various parameters, including slump, Vebe time, density, water absorption (WA), ultrasonic pulse velocity (UPV), thermal conductivity coefficients (k), compressive strength (CS), and splitting tensile strength (STS) across six different SLWC formulations. The results indicate that while SF negatively impacted the workability of SLWC mortars, it improved CS and STS due to the formation of calcium silicate hydrate (C-S-H) gels from SF's high pozzolanic activity. Additionally, using micro-PP fibers in combination with macro-PP fibers rather than solely macro-PP fibers enhanced the workability, CS, and STS of the SLWC samples. Although SF had a minor effect on reducing thermal conductivity, the use of macro-PP fibers alone was more effective for improving thermal properties by creating a more porous structure compared to the hybrid use of micro-PP fibers. Moreover, increasing the ratio of micro- and macro-PP fibers from 0.3% to 0.6% resulted in lower CS values but a significant increase in STS values. [ABSTRACT FROM AUTHOR]

This study investigated the mechanical and microstructural properties of lightweight aggregate geo-polymer concrete (LWAGC) produced by alkali-activating glass powder (GP) and Fly Ash (FA) at elevated temperatures ranging from 200 to 800°C. It also examined the effects of incorporating crushed foam masonry (RFA) and crushed porcelanite rock aggregates (PA) into FA and GP-based geo-polymer concrete, both before and after exposure to ambient and high temperatures. A low-calcium type of FA was used as a binder in the geo-polymer concrete paste, with a 10 % replacement of glass powder. The concrete samples were heated at temperatures of 200°C, 400°C, 550°C, and 800°C for a duration of 60 minutes, with a heating rate of 7°C per minute. It was observed that the inclusion of weaker coarse aggregate resulted in a reduction of the compressive strength of the concrete. The geo-polymer concrete was subjected to tests for water absorption, mass loss, cracking, and microstructure analysis at elevated temperatures. The findings indicate that at heating temperatures of 400°C and above, the geo-polymer concrete underwent degradation and dehydration. The test findings also revealed residual compressive strengths of 104.9 %, 97.2 %, 81.8 %, and 64.2 % for the (RFA) types, and 107.3 %, 94.8 %, 78.3 %, and 58.8 % for the (PA) types. Additionally, the density decreased by 1.02 %, 4.88 %, 8.10 %, and 13.88 % for (RFA) and (PA) types, respectively, and by 0.27 %, 1.91 %, 4.67 %, and 10.79 % overall. The results indicate that the compressive strength of the concretes increased after exposure to elevated temperatures of 35°C and 200°C. However, when exposed to temperatures ranging from 400°C to 800°C, the strength of the LWAGC started to degrade and decline. Based on the obtained findings, the present study recommends performing laboratory tests on construction waste generated during demolition while developing and evaluating numerical models that predict the behavior of the resulting demolition materials when incorporated in the production of geo-polymer concrete. [ABSTRACT FROM AUTHOR]

The research aims to investigate SCGC performance as a suitable alternative to the traditional concrete. The research will study the effect of LWCA, steel fiber and curing condition on the fresh and hardened properties of SCGC. The main materials will be used for SCGC are fly ash and slag. Curing will be performed using oven, and ambient temperature. Steel fibers SF will be incorporated into the mixture at 0%, 0.5%, 1% and 1.5% of binder content. While the natural coarse aggregate will be replaced by LWCA with 0%, 33.3%, 66.67% and 100% by weight. Analysis of this (SCGC) were done for both fresh and hardened state to assess the mechanical properties of (SCGC). This study finds that the addition of both LWCA and SF decreased the blend's L-Box ratio and slump flow value. All SCGC mixtures fulfilled the EFNARC guidelines and standards. Results reported that Mixes with a greater percentage of LWCA and SF became more cohesive and viscous. Results revealed that the SCGC exposed into ambient air curing condition had lower flexural strength, compressive strength, and tensile strength than of heating curing condition. The compressive strength CS of samples(M1-M9) exposed to heating conditions compared to the ambient ones increased about 36.09%, 26.32%, 17.88%, 23.87%, 27.96%, 27.69%, 38.94%, 27.91% and 24.53% respectively. The better CS values were 38.94% for M7 mix and 36.08% for M1 Mixtures. The FS of samples exposed to heating conditions compared to the ambient ones increased about 13.39%, 13.39%, 23.78%, 18.64%, 17.85%, 11.67%, 34.70%, 8.65% and 12.24% respectively the better flexural strength value was 34.70%, of M7 mix exposed to heating conditions. The better TS value was 26.22 Mpa for M3 Mixes at 1.5% of SF, While the TS reported dropping about 38.4% when applying LWCA as partially replacement of 66.67% with ambient curing condition. The study findings that the (CS) of mixes were proportional directly with steel fibers percentage till (1.0%). The CS, FS and TS of SCGC decreased when increasing LWCA. As a result, the SCGC that cured in oven showed enhancement in each fresh and mechanical properties, therefore, it is recommend to utilize the (SCGC) in hot areas and utilize wastes such as steel fibers and LWCA in SCGC as an economic, affordable and eco-friendly material. [ABSTRACT FROM AUTHOR]

This study explores the impact of varied cement doses (250, 275, 300, 325, and 350 kg/m³) and granular classes (Dmax of 8, 10, 12.5, and 20 mm) on pervious concrete characteristics. The concrete's fresh and hardened states are examined to identify the ideal cement dosage and granular class for optimal properties. Workability in the fresh state is measured using the slump test and air content analysis. In the hardened state, performance is assessed through water permeability, porosity, density, compressive strength, and electrical resistivity tests. The research reveals that granular class Dmax significantly affects pervious concrete properties. A smaller Dmax and lower cement dosage enhance workability, while in the hardened state, a smaller Dmax combined with higher cement dosage reduces porosity and water permeability and increases mechanical strength and density. The ideal combination of cement dose and granular class varies depending on the specific property under consideration. This study emphasizes the importance of carefully selecting granular class and cement dosage to achieve desired pervious concrete qualities. These findings provide valuable insights for practitioners aiming to enhance the sustainability and resilience of urban infrastructure using pervious concrete. [ABSTRACT FROM AUTHOR]

It was understood that various studies were carried out on the strength, permeability, durability, increasing the thermal performance of lightweight concrete facade panels, and sustainable and energy‐efficient concepts. It was observed that fiber was added to the mixture to improve the properties in question. However, it was determined that contradictory results were obtained due to the large number of active parameters and whether the fiber was distributed homogeneously in the matrix. In this study, the effects of fiber type, length and usage rate on the strength, energy absorption capacity, elasticity modulus, water absorption, and thermal performance of lightweight concrete mixtures were investigated. For this purpose, three different types of fibers of different lengths: polypropylene (3, 6, and 12 mm), glass (13 and 25 mm) and polyamide (6 and 12 mm) were used at 0%, 0.25%, 0.50%, and 0.75% of the total volume. It was determined that the mixture containing 0.25% polypropylene fiber with a length of 3 mm exhibited the best performance in terms of both mechanical and thermal properties. In terms of these features, it was understood that the mixtures with 12 mm polypropylene with a usage rate of 0.75% and 6 mm polyamide fibers with a usage rate of 0.50% had the weakest performance. [ABSTRACT FROM AUTHOR]

The behaviour of lightweight concrete (LWC) edge column-slab connections reinforced with two types of flexural reinforcement glass fiber-reinforced polymer (GFRP) and steel bars with different ratios of shear reinforcement are investigated experimentally and analytically using ABAQUS software. The experimental protocol covered evaluation of eight slabs and edge columns measuring subjected to static loading. Slabs are evaluated as supported, free-standing at one edge, and the column connection is included. The slabs are divided into two groupings, with four slabs in each group. The first group was reinforced with steel flexural, while the second group was reinforced with GFRP reinforcement. Within each group, one slab lacked shear reinforcement, while the other was reinforced with a varying shear reinforcement ratio. A good agreement was found between the numerical FE model and experimental outcomes in most tested slabs. [ABSTRACT FROM AUTHOR]

Geopolymer lightweight cellular concrete (GLCC) combines the advantages of geopolymer and LCC but also suffers from the inherent deficiency of low strength, which can be improved by introducing suitable reinforcing materials such as fibers. This paper investigated the mechanical properties and microstructure of fly ash-slag-based GLCC reinforced with glass fibers (GLCCRGF), aiming to reveal the strengthening mechanism of glass fibers. The effects of different fiber contents (0.0, 0.3, 0.6, 0.9, and 1.2%), fiber lengths (3, 6, 9, 12, and 15 mm), and fiber-blending methods (G-R, G-W, and G-S) on the mechanical properties of GLCCRGF were analyzed. The results showed that the fiber incorporation had no significant or even negative effect on the compressive strength but significantly improved the splitting tensile strength. The optimal results of fiber content, fiber length, and fiber-blending method are 0.6%, 9 mm, and G-R, respectively. From the microstructure perspective, optical tests were conducted to explore the evolution rules of pore size, pore shape factor, and fractal dimension of pore distribution of GLCCRGF. The results showed that the incorporation of glass fibers (0.6%, 9 mm, and G-R) improved the pore characteristics and contributed to more uniform pore distribution. Furthermore, scanning electron microscopy (SEM) was employed to observe the micromorphology of the skeleton structure of GLCCRGF. The SEM results showed excellent interfacial bonding between glass fibers and the geopolymer matrix. Due to good bonding quality and crack-bridging effect, the presence of glass fibers enhanced the strength and crack resistance of the matrix. [ABSTRACT FROM AUTHOR]

In this paper, a novel pervious concrete (PC) has been proposed, which combines a high-strength self-compacting concrete matrix with artificial pore channels, to prepare a novel self-compacting recycled pervious concrete (NSRPC) with vertically and uniformly distributed pore channels. Then, an analysis was conducted to assess the flexural performance, permeability, and resilience to rainstorm of NSRPC after flexural fatigue load, which was carried out to ascertain the fluctuations in strength and drainage efficiency over the anticipated service life. The experimental results of NSRPC with porosity levels of 0.28%, 0.56%, 0.84%, and 1.12% show that the reduction in rainstorm will first decrease and then increase with the increase of fatigue cycles. After 2×105 fatigue cycles, the corresponding NSRPC flexural strength was 5.9, 5.6, 5.4, and 4.5 MPa, respectively, and the ultimate displacement decreased by 20.2%, 25.1%, 28.0%, and 33.1%, respectively. After 2×105 fatigue cycles, NSRPCs still demonstrate good storm waterlogging resistance under 20-, 50-, and 100-year rainstorms. The maximum water retention dissipation rate of NSRPC can reach 0.13 mm/min , and the maximum water retention depth is less than 2.5 mm. Additionally, the permeability coefficient of NSRPC remains almost unchanged with an increase in fatigue cycles. When the permeability coefficient is greater than 4.5 mm/s , the depth of stagnant water remains almost constant with the increase of the permeability coefficient. The research in this project provides a new material and direction for the study of pervious concrete to control rainstorms and waterlogging. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Attapulgite is a natural clay mineral, that has been investigated as a potential lightweight aggregate due to its low density and unique structural properties. Recently, the interest in using attapulgite has increased. In this study, the combined attapulgite (fine and coarse) is used in a concrete mixture. Tests were conducted to select the best content of attapulgite in mixtures by investigating its properties, including slump, compressive strength, and density characteristics to evaluate Lightweight Concrete (LWC) performance. The outcomes exhibited that different attapulgite aggregate contents influence compressive strength, with the highest value being 21 MPa for 984 kg/m³ attapulgite content at 28 days of curing. Furthermore, the dry density is positively correlated with the increment of the attapulgite aggregate percentage. Then, different percentages of Superplasticizer (SP) of 0.9%, 1.1%, 1.3%, 1.5%, and 1.7% were utilized, which led to the enhancement of the slump flow. The ideal ratio adopted for the subsequent mixtures was 1.3% by weight of cementitious material, which gave the highest compressive strength (26.2 MPa at 28 days). Also, mixtures in which cement was replaced by fly ash of 10%, 20%, 30%, 60%, and 100% ratio by weight of cement were prepared. The results demonstrated that the highest compressive strength was 32.7 MPa with a 30% ratio of fly ash by weight of cementitious materials after 90 days of curing. [ABSTRACT FROM AUTHOR]

One of the most crucial ecological challenges is the removal of the ever increasing enormous quantities of Fly Ash (FA) generated from various industries and its reduction in landfill spaces. Light-Weight Aggregate Concrete (LWAC) is utilized in the construction industry as it can decrease the unit weight leading to lower dead load, thermos-insulation, and resistance against earthquakes. A number of researchers have implemented experimental programs on the use of large amounts of FA as a substitute for cement in various lightweight concrete mixtures. This study aims to present the recent efforts of adding attapulgite in LWAC and highlight its effects and the influence of its mixture with High Volume FA Light-Weight Concrete (HVFALC) in terms of compressibility resistance, tensile strength, and rupture resistance. [ABSTRACT FROM AUTHOR]

Indonesia experiences frequent earthquakes due to its proximity to seismic faults. Many one- or two-story residential buildings with reinforced concrete frames filled with masonry are severely damaged during moderate to high-magnitude earthquakes. One solution to reduce seismic loads on the structures is the use of Cellular Lightweight Concrete (CLC). The behavior of CLC block panels as an infill wall against lateral cyclic loading is the subject of this experimental investigation. The specimens consist of two Reinforced Concrete (RC) frame models: a CLC block panel used as an infill wall for the RC frame (DB-2) and a reinforced concrete frame (DB-1). This research uses displacement control methods and lateral cyclic loading to evaluate the behavior of wall structures according to the ASTM E2126-02a. The results showed that the strength value of the DB-2 specimen was 29.61% higher than that of the DB-1 specimen. Neither loading nor unloading of the DB-2 specimen caused a decrease in relative stiffness, unlike the DB-1 specimen. This indicates that the DB-2 specimen does not experience a squeezing effect and instead becomes more stable and has improved energy dissipation without losing strength. The results show that bricks, concrete blocks, and other fillers can be replaced with precast CLC panels for reinforced concrete frame walls. [ABSTRACT FROM AUTHOR]

This study investigates the behavior of the shear strength of fibrous concrete I-beams made from normal and lightweight concrete that have the same compression strength, of about 30 MPa. Lightweight aggregate concrete was made by replacing 75% of the coarse aggregate with lightweight aggregate (Bonza stone). Fourteen concrete I-beams with dimensions of 1000x210x175 mm were divided into two groups. In the first group, the web area was reinforced with steel fiber added in 0.5%, 1%, and 1.5% of the mix volume. The second group was reinforced with glass fiber added in the same percentage as the steel fiber. The results showed that the shear strength of a Normal Concrete Beam with Steel Fibers (NCSF) is increased by 3.5%, 13.5%, and 13.3% for the addition ratios of 0.5%, 1%, and 1.5%, respectively, compared to the Normal Concrete Beam without Fibers (NC). Webs with glass fibers gain an increase of about 3.7% and 14.05% for the addition ratios of 0.5% and 1%, respectively, while the shear strength decreased by 6.21% for the addition ratio of 1.5%. On the other hand, the Lightweight Concrete Beam with Steel Fibers (LWCBSF) achieved greater shear strength than the Lightweight Concrete Beams without Fibers (LWCB) by 4.8%, 13.5%, and 10.9%; for the three additional percentages, respectively. The shear strength increased by 8.4% and 11.04% for the Lightweight Concrete Beam with Glass Fibers (LWCBGF) at 0.5% and 1% ratios, while the shear strength decreased by 11.9% for the 1.5% glass fibers ratio compared to the Lightweight concrete Beam without Glass Fibers (LWCB). The best performance, according to the ultimate load, was achieved when fibers were added at a ratio of 1% in normal and lightweight concrete compared to other ratios. [ABSTRACT FROM AUTHOR]

A new type of lightweight shear wall has been developed using composite panels, with styrofoam as the core layer and calcium board as the skin layer. This innovation aims to facilitate the rapid construction of housing in response to earthquake disasters. Physical testing of the material showed an increase in the compressive strength of the styrofoam core, from 2.14 MPa to 3.74 MPa in 75 mm thick sandwich panels. This study examines the use of precast panels with specific installation techniques involving pick-up beams (sloofs), connectors, and panel to panel connections to enhance wall strength against horizontal earthquake loads. The conducted cyclic loading test followed the ASTM E2126-18 (2018) standard loading cycle pattern test method. Lateral force experiments were conducted on full-scale shear walls with two different panel-frame connection modes. The test results revealed the behavior of Panel Lightweight Concrete (PLC) walls under cyclic lateral forces. Combined wall panels acted independently, and the use of PVAc adhesive and steel connectors resulted in a unified wall behavior system. The displacement behavior of the wall within the pinch system in the notch on the sloof demonstrated positive results. Quipanel walls can reduce building weight, mitigate earthquake forces, and provide a robust structure capable of withstanding long-term lateral forces. This development leads to the construction of simple, earthquake-resistant houses. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Translation abstract Lightweight ceiling elements made of carbon‐reinforced concreteIn concrete components under bending, a large proportion of the material used is underutilized. More material efficiency can be achieved, e. g., by resolving the solid interior of such components. In the presented project, this is realized by load‐bearing filigree carbon‐reinforced concrete membranes. At first, in the article, the method of producing such filigree structures by casting under negative air pressure is briefly explained and the material properties achieved in standard tests are discussed. Then, the design of two 1.8 m × 1.8 m large slabs and their load‐bearing behavior in 9‐point bending tests are described and compared with numerical simulations. Finally, an outlook on future research is given. [ABSTRACT FROM AUTHOR]

To study the performance of lightweight foamed concrete (LWFC) in widened embankments of high-speed railways, this study first conducted numerous strength, permeability, and water immersion tests to investigate the mechanical properties and water resistance of LWFC with designed dry densities of 550, 600, and 650 kg/m3. Secondly, a field test was performed to analyze the behavior of the deformation and the internal pressure within the LWFC-filled portions. Furthermore, a parametric study via numerical modeling was performed to investigate the effects of four key factors on the performance of the LWFC-filled, widened embankments. Results showed that LWFC possesses adequate bearing capacity and impermeability to meet high-speed railway embankment widening requirements. However, water seepage reduces LWFC strength. The additional pressure from LWFC filling increases initially but then decreases once dehydration occurs. The settlement induced by LWFC accounted for 71% of the total filling height, which is only 37.5% of the total settlement after construction. The parametric study results show that the maximum settlement of widened and existing portions induced by LWFC was 46.3–49.6% and 48.3–53.2% of those induced by traditional fillers due to the LWFC's lower density as well as their better self-supporting ability. Making an appropriate reduction in the thickness of the retain wall installed against the LWFC-filled widened embankment of the high-speed railway generates a few variations in the lateral deformation of the wall. Furthermore, the effects of the pile offset on the deformation of the LWFC-filled embankment were more sensitive compared to the diameter of the piles. [ABSTRACT FROM AUTHOR]

The development of self-compacting lightweight concretes is associated with solving two conflicting tasks: achieving a structure with both high flowability and homogeneity. This study aimed to identify the technological and rheological characteristics of the flow of concrete mixtures D1400...D1600 based on hollow microspheres in comparison with heavy fine-grained D2200 concrete and to establish their structural and physico-mechanical characteristics. The study of the concrete mixtures was carried out using the slump flow test and the rotational viscometry method. The physical and mechanical properties were studied using standard methods for determining average density and flexural and compressive strength. According to the results of the research conducted, differences in the flow behaviors of concrete mixtures on dense and hollow aggregates were found. Lightweight concretes on hollow microspheres exhibited better mobility than heavy concretes. It was shown that the self-compacting coefficients of the lightweight D1400...D1600 concrete mixtures were comparable with that of the heavy D2200 concrete. The rheological curves described by the Ostwald–de Waele equation showed a dilatant flow behavior of the D1400 concrete mixtures, regardless of the ratio of quartz powder to fractionated sand. For D1500 and D1600, the dilatant flow behavior changed to pseudoplastic, with a ratio of quartz powder to fractional sand of 25/75. The studied compositions of lightweight concrete can be described as homogeneous at any ratio of quartz powder to fractional sand. It was shown that concrete mixtures with a pronounced dilatant flow character had higher resistance to segregation. The value of the ratio of quartz powder to fractional sand had a statistically insignificant effect on the average density of the studied concretes. However, the flexural and compressive strengths varied significantly more in heavy concretes (up to 38%) than in lightweight concretes (up to 18%) when this factor was varied. The specific strength of lightweight and heavy concrete compositions with a ratio of quartz powder to fractional sand of 0/100 had close values in the range of 20.4...22.9 MPa, and increasing the share of quartz powder increased the difference between compositions of different densities. [ABSTRACT FROM AUTHOR]

Foam concrete has been used in various real-life applications for decades. Simple manufacturing methods, lightweight, high flowability, easy transportability, and low cost make it a useful construction material. This study aims to develop foam concrete mixtures for various civil and geotechnical engineering applications, such as in-fill, wall backfill and soil replacement work. A blended binder mix containing cement, fly ash and silica fume was produced for this study. Its compressive strength performance was compared against conventional general purpose (GP) cement-based foam concrete. Polypropylene (PP) fibre was used for both mixtures and the effect of various percentages of foam content on the compressive strength was thoroughly investigated. Additionally, two types of foaming agents were used to examine their impact on density, strength and setting time. One foaming agent was conventional, whereas the second foaming agent type can be used to manufacture permeable foam concrete. Results indicate that an increase in foam content significantly decreases the strength; however, this reduction is higher in GP mixes than in blended mixes. Nevertheless, the GP mixes attained two times higher compressive strength than the blended mix's compressive strengths at any foam content. It was also found that the foaming agent associated with creating permeable foam concrete lost its strength (reduced by more than half), even though the density is comparable. The compressive stress–deformation behaviour showed that densification occurs in foam concrete due to its low density, and fibres contributed significantly to crack bridging. These two effects resulted in a long plateau in the compressive stress–strain behaviour of the fibre-reinforced foam concrete. [ABSTRACT FROM AUTHOR]

AbstractThis research evaluates the impact of aggregate sizes on pervious concrete properties, comparing aggregates of 12.5 mm and 19 mm, as well as replacing natural aggregates with recycled aggregates set at 0% and 50%. Four types of pervious concrete were produced, and their properties were determined: density, porosity, permeability coefficient, compressive strength, flexural tensile strength, and abrasion resistance. The results indicate that water permeability is directly related to pore size and is influenced by aggregate size (90% of the variation in pervious concrete permeability) and, to a lesser extent, by recycled aggregate content (10% of the variation). Mixes with larger aggregates (19 mm) demonstrated higher permeability coefficients. Replacing natural aggregates with recycled aggregate did not significantly affect the mechanical properties of pervious concrete, highlighting the effectiveness of waste processing and mixing procedures, allowing for the incorporation of 50% of recycled aggregate. The concretes met the requirements of the American Concrete Institute, suggesting technically feasible conditions for sustainable practices in the construction industry. [ABSTRACT FROM AUTHOR]

Concrete stands as a fundamental material in the construction industry. However, it encounters challenges such as cracking, crumbling, or disintegration at elevated temperatures, attributed to high thermal stresses and low tensile strength. This study addresses these issues by reinforcing concrete samples with steel and polypropylene fibres, exposing them to temperatures ranging from 25 to 800°C, and conducting mechanical tests. In order to provide a comprehensive examination, a concrete mixture containing lightweight aggregate was also prepared and tested along with other mixtures. The test results showed that adding steel and polypropylene fibres enhanced or maintained compressive strength up to 200°C compared to the control sample. Furthermore, samples containing steel fibres exhibited the highest tensile strength across all temperatures. Notably, at 600°C and above, the lightweight concrete sample demonstrated comparable or superior compressive strength as well as tensile strength compared to the control sample. In addition, it was observed that polypropylene fibres began to melt at 400°C, leading to a decline in compressive and tensile strength in samples containing this fibre type at temperatures exceeding 400°C. [ABSTRACT FROM AUTHOR]

A supermarket made of infra‐lightweight concrete – Proof of stability for a fire wall Infra‐lightweight concrete (ILC) is a special form of lightweight concrete which, due to its low density, possesses improved thermal insulation properties in comparison to normal concrete. ILC facilitates the construction of monolithic, single‐layer building skins without any added thermal insulation or facade cladding. This way, the building components are effectively simplified in comparison to conventionally insulated concrete members and the recyclability is significantly improved. In addition to that, structural elements made of ILC have a reduced CO2 footprint in comparison to conventional composite elements of the building envelope. After 15 years of research and several completed construction projects in the housing and education sector, a commercial retail building has been realized. For this project, an individual approval for a firewall built out of ILC was obtained based on a fire test in combination with a transfer concept based on calculations. This article demonstrates the transfer concept as well as a simplified structural analysis concept for the proof of stability developed for the special application of a firewall. [ABSTRACT FROM AUTHOR]

The goal of this research focusing on the burning of coal tailings to produce a lightweight artificial aggregate is to compare the physical-mechanical and durability properties of concrete containing this new type of artificial aggregate with those of the reference concrete. The following parameters are measured on all the samples: compressive strength, volume mass, the static modulus of elasticity in compression, the frost resistance of this new type of concrete, and the resistance to CO2. All the concretes tested with the new artificial aggregate exceeded the characteristic strength values in all the strength classes monitored. The volume mass of the concrete with the new artificial aggregate is tens of percentages lower than that of the conventional reference concrete. The frost resistance of the concrete tested was reliably proven by the non-destructive resonance method. It was also found that at the lower strength classes of concrete, carbonation occurred earlier, but there was no obvious direct relation to the porosity of the new artificial aggregate. The tests performed showed that it is possible to produce high - quality concrete using a new lightweight artificial aggregate produced from coal tailings [ABSTRACT FROM AUTHOR]

To reduce land use and avoid further pollution, incineration for power generation has become the main method for municipal solid waste treatment. This research focused on the potential for transforming Municipal Solid Waste Incineration Bottom Ash (MSWIBA) into a finely ground powder. The impact of the powder's fineness and the amount of water used on its effectiveness was analyzed using a method called grey theory. MSWIBA was used as a partial substitute for cement in making MSWIBA foam concrete and lightweight wall panels. By modifying the fineness and water utilization of the recycled micro-powder, its maximum activity index can be increased to 90.1. This study determined the influence of factors including apparent dry density, water–cement ratio, foaming agent dilution ratio, and admixture dosage on the strength of the recycled foam concrete, and established the optimal mix ratio. This study employed a combination of physical experiments and numerical simulations to elucidate the impact of panel material, core layer thickness, and layer sequence on sound insulation performance. The simulation results were in close agreement with the experimental findings. [ABSTRACT FROM AUTHOR]

The current study examines the strength and transport properties of reclaimed asphalt pavement (RAP) inclusive pervious concrete (PC) pavement mixes containing various industrial and agricultural wastes such as silica fume (SF), fly ash (FA), and bagasse ash (BGA). Apart from a conventional PC mix (containing natural aggregates) and a 100% RAP inclusive PC mix, seven different mixes were developed by mixing 100% RAP aggregates with SF (5 and 10%), FA (10 and 15%), and BGA (5, 10, and 15%) as partial replacements for ordinary Portland cement. The above-mentioned PC pavement mixes were investigated for density, porosity, permeability, compressive strength, modulus of rupture, and abrasion resistance. The interconnected pore structure of conventional PC and RAP-PC pavement mixes was investigated using 2D image analysis and X-Ray microcomputed tomography. Based on the laboratory results, it can be stated that the inclusion of RAP significantly improves the transport properties of PC pavement mixes with increased porosity and permeability values. This was primarily due to a more interconnected pore matrix and lesser isolated voids in the RAP-PC pavement mix. The addition of SF could only improve the strength parameters (compressive strength and modulus of rupture) of the RAP-PC pavement mix. In contrast, BGA inclusion was observed to improve its transport properties (porosity and permeability). Furthermore, the inclusion of SF, FA, and BGA in a 100% RAP-PC mix improved abrasion resistance. When compared to the conventional PC pavement mix, incorporating RAP aggregates blended with SF, FA, and BGA can reduce the production cost of 1 m3 PC by 30–61% and lower CO2 emissions by 13–21%. However, considering the strength and transport property requirements of PC mixes, as well as the economic and environmental viability, the present investigation recommends using 5% SF, 10% FA, and 10% BGA in a 100% RAP-PC pavement mix. [ABSTRACT FROM AUTHOR]

The recent emphasis on sustainability issues in construction materials has increased the interest to examine the effect of recycled aggregates on the performance of pervious concrete. This study investigated the effects of different types of recycled coarse brick aggregates (RCBAs), maximum RCBA size and using recycled fine brick aggregates (RFBAs) on the performance of pervious concrete. This has been done by testing void, density, compressive strength, splitting tensile strength, permeability, dust clogging and abrasion resistance. The quality of effluent passed through pervious concretes was also studied. According to the results, the usage of different types of RCBA decreased the compressive strength of pervious concrete, with the highest strength reduction of 55.3% which was obtained for 50% RCBA type A. A larger porous network of concretes by the incorporation of RCBA resulted in a higher permeability coefficient of up to 24.9%. Moreover, using RFBA in pervious concrete produces a much denser matrix and hence provides higher compressive and splitting tensile strengths and lower permeability coefficient. The permeability loss of pervious concretes due to dust clogging can also be decreased at 50% incorporation of different types of RCBA. Furthermore, results showed that RCBA types mainly influence the abrasion resistance of pervious concrete. Statement of Novelty: Different types of waste bricks may have different physical and mechanical properties which necessitated comprehensive experimental research about their performance in pervious concrete. To cover the gaps in this field, this research was conducted to investigate the effect of three major factors including (1) three different types of recycled coarse brick aggregates, (2) maximum aggregate size and (3) using recycled fine brick aggregates on the performance of pervious concrete. [ABSTRACT FROM AUTHOR]

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lightweight concrete (LWC) finds wide-ranging applications in the construction industry due to its reduced dead load, good fire resistance, and low thermal and acoustic conductivity. Lightweight geopolymer concrete (LWGC) is an emerging type of concrete that is garnering attention in the construction industry for its sustainable and eco-friendly properties. LWGC is produced using geopolymer binders instead of cement, thereby reducing the carbon footprint associated with conventional concrete production. However, the absence of standard codes for geopolymer concrete restricts its widespread application. To address this limitation, an investigation focused on developing a new mixture design for LWGC by modifying the existing ACI 211.2-98 provisions has been carried out. In this study, crucial parameters of LWGC, such as alkaline-binder ratio (A/B), molarity, silicate/hydroxide ratio, and curing temperature, were established using machine learning techniques. As a result, a simple and efficient method for determining the mixture proportions for LWGC has been proposed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents an analysis of the effect of concrete salinity on the splitting tensile strength of specimens taken directly from the HC-500 floor slab and the flexural and compressive strength and the value of the modulus of elasticity of specimens made under laboratory conditions from lightweight concrete and ordinary concrete. The tests were carried out in two variants: in the first, chloride ions were introduced into the concrete by the migration method and in the second, as an additive introduced directly with the batch water. The analysis showed that the additive can affect certain mechanical properties of concrete both favorably and unfavorably. The results indicate that it is important to examine the issue of the influence of salinity on concrete's mechanical properties. This knowledge can be applied to the modeling of damage in reinforced concrete structures resulting from exposure to chloride-rich environments. [ABSTRACT FROM AUTHOR]

The recycling of construction wastes holds significant importance both environmentally and economically. While extensive research has been conducted on aggregates derived from various wastes, the recycling of pervious concretes (PC) has been largely overlooked. This study addresses this gap by examining the porosity and mechanical properties of PC manufactured using aggregates obtained from recycled PC. The investigation focuses on three key factors: aggregate size (5/15, 10/15, and 15/25 mm size fractions), fiber inclusion (dosages of 0.1%, 0.2%, and 0.3% by volume), and aggregate type (limestone aggregate and recycled aggregate). Through image processing techniques, void characteristics including amount, structure, and homogeneity were quantified. Results indicate that the use of recycled aggregate led to a decrease in compressive strength ranging from 29% to 65%, depending on aggregate size fraction and fiber content. Porosity assessments revealed higher porosity in concrete utilizing recycled aggregate, with computer-based methods yielding values closely aligned with volumetric results. [ABSTRACT FROM AUTHOR]

A versatile building material, foamed concrete is made of cement, fine aggregate, and foam combined with coarse aggregate. This study provides a description of how constant coarse aggregate replacement (50%) of LECA and foamed concrete, which are lightweight concrete types, by zeolite as a filler and PEG-400 as a plasticizer, water retention agent, and strength enhancer affect the mechanical properties of the cement. A study that examined the characteristics of cellular lightweight concrete in both its fresh and hardened forms was carried out for both foamed concrete and LECA concrete. In order to do this, a composite of zeolite and polyethylene glycol 400 was made using the direct absorption method, and no leakage was seen. Zeolite was loaded to a level of 10% and 20% of the total weight in cement, while 400 g/mol PEG was used at levels of 1%, 1.5%, and 2% of the cement's weight. Various mixtures having a dry density of 1250 kg/m3 were produced. Properties like dry density, splitting tensile strength, and compressive strength were measured. An increase in the amount of PEG400–zeolite was seen to lower the workability, or slump, of both foamed and LECA concrete, while the replacement of aggregate by zeolite resulted in an exponential drop in both compressive and flexural strengths. [ABSTRACT FROM AUTHOR]

The new railway line connecting Luxembourg and Bettembourg crosses the A3 highway at a steep angle (19.5°) with the bridge called OA14. The designed bridge is a bowstring structure with a single span of 186.85 meters. The bridge deck consists of two lateral metal box girders acting as a chord. The deck is a transversal filler beam, with spherical voids and lightweight concrete to reduce the structure's weight. The bridge features two inward‐inclined arches at 9°, which are doubled and serve as trusses. This significantly increases the stiffness of the arch whilst keeping the silhouette elegant. The deck follows the curved track alignment, the arches remain straight. Two times 12 hangers connect the arches to the girders, they are made of CHS profiles of S450H quality. This article gives an overview of the structure and its construction. It then gives a more detailed insight in the design of the hangers, especially the hanger‐girder connections. [ABSTRACT FROM AUTHOR]

The utilization of lightweight aggregate concrete (LWC) plays a major role in reducing the self-weight of CFST (concrete-filled steel tube) columns, which is reflected in the behavior of the structural system. This paper aims to investigate the characteristics of lightweight concrete-filled steel tubular (LWCFST) columns under an axial compressive load, using a total of (48) LWCFST column models. The simulated models were divided into four groups with different concrete compressive strength, length-to-diameter ratios (L/D), and diameter-to-thickness ratios (D/t). Four concrete compressive values were examined (30, 40, 50, and 60) MPa, three length-to-diameter ratios short (L/D = 3), medium (L/D = 6), and long (L/D = 9), and four diameter-to-thickness ratios (36, 31, 26, and 21). The method of nonlinear finite element analysis (NLFEA) was used to fulfill the objective of this study where results were presented as graphical plots between the compressive loading versus the axial and lateral strains along with the failure modes. In addition, the results were compared with the AISC360-16 and EC4 codes predictions to examine their applicability on the LWCFST columns where the AISC was overpredicted in most cases with higher percentages under lower (L/D) values, whereas the EC2 was underestimated in most cases with high percentages up to 28%, which become closer to the NLFEA predictions at higher (L/D) values. It has been revealed that the utilization of steel tubes significantly improves the LWCFST column's mechanical performance, ductility, compressive strength, and toughness. Moreover, the structural behavior of the LWCFST columns and their associated failure modes was found to be highly affected by the geometrical properties of the CFST column (i.e., L/D ratio and D/t ratio) where specimens with small tube thickness show bad behavior. Finally, the utilization of high-strength concrete has a favorable performance compared to the utilization of thick steel tubes. [ABSTRACT FROM AUTHOR]

In this study, an experimental program was conducted to investigate the shear behavior of beams made of high-strength and lightweight cementitious composites (HS-LWCCs) containing hollow glass microspheres and carbon nanotubes. The compressive strength and dry density of the HS-LWCCs were 87.8 MPa and1.52 t/m3, respectively. To investigate their shear behavior, HS-LWCC beams with longitudinal rebars were fabricated. In this test program, the longitudinal and shear reinforcement ratios were considered as the test variables. The HS-LWCC beams were compared with ordinary high-strength concrete (HSC) beams with a compressive strength of 89.3 MPa to determine their differences; the beams had the same reinforcement configuration. The test results indicated that the initial stiffness and shear capacity of the HS-LWCC beams were lower than those of the HSC beams. These results suggested that the low shear resistance of the HS-LWCC beams led to brittle failure. This was attributed to the beams' low elastic modulus under compression and the absence of a coarse aggregate. Furthermore, the difference in the shear capacity of the HSC and HS-LWCC beams slightly decreased as the shear reinforcement ratio increased. The diagonal compression strut angle and diagonal crack angle of the HS-LWCC beams with shear reinforcement were more inclined than those of the HSC beams. This indicated that the lower shear resistance of the HS-LWCCs could be more effectively compensated for when shear reinforcement is provided and the diagonal crack angle is more inclined. The ultimate shear capacities measured in the tests were compared with various shear design provisions, including those of ACI-318, EC2, and CSA A23.3. This comparison showed that the current shear design provisions considerably overestimate the contribution of concrete to the shear capacity of HS-LWCC beams. [ABSTRACT FROM AUTHOR]

Sludge ceramsite (SC) can be utilized as a lightweight aggregate in concrete, especially in external wall materials, due to the increasing volume of polluted sludge, which contributes to water system deterioration and poses greater threats to human health. The influence of the fresh mortar's slump flow on the dispersion of ceramsite was studied. The ultrasonic sound velocity, capillary water absorption rate, compressive strength, and coefficient of variation (CV) were measured in this study. Thermogravimetric (TG) analysis, ultra depth-of-field microscope scanning, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) were used to analyze the performance mechanism of the ceramsite concrete. The results indicated that adding SC could reduce the fluidity of the fresh concrete, with a reduction by rates of up to 2.04%. The addition of WRA could improve the fluidity by rates of up to 60.77%. The relationship between the ultrasonic sound speed and the increasing fluidity could be deduced as a negative correlation. The water absorption was negatively correlated with the compressive strength. The concrete with a slump flow of 12.35 and 12.5 cm reached the maximum compressive strength, which had the lowest water absorption, and demonstrated internal homogeneity. The optimum slump flow was 12.35 and 12.5 cm. With the slump flow of 12.5 cm, the corresponding CV was the lowest, showing the optimum SC's dispersion. Through TG, XRD, and SEM analyses, it was verified that the addition of 0.6% WRA promoted the hydration of cement. In addition, SC increased the hydration products. [ABSTRACT FROM AUTHOR]

Abstract Lightweight concrete, particularly polystyrene concrete, has been extensively utilized in civil engineering for decades. The incorporation of waste expanded polystyrene (EPS) as a filler material in the production of lightweight concrete presents significant advantages from a circular economy perspective. Prior research indicates that increasing the proportion of lightweight aggregates, such as EPS, typically results in reductions in strength and bulk density. The utilization of substantial amounts of EPS waste in the formulation of structural polystyrene concrete is crucial for advancing sustainable construction practices. This study investigates the effects of varying nano-silica content on the bulk density, compressive strength, flexural strength, splitting tensile strength, and water penetration depth of structural polystyrene concrete. Concrete specimens were prepared by substituting 25%, 50%, 75%, and 100% of sand with EPS waste, while evaluating nano-silica contents of 0.75%, 1%, and 1.25%. The findings reveal that increasing the volume fraction of EPS corresponds to a decrease in the concrete’s bulk density. This research provides critical insights into optimizing structural lightweight concrete, thereby promoting advancements in sustainable construction applications.

A concrete slab is one of the chief structural members in buildings, considered the most prominent member consuming concrete. Structural engineers are challenged to work on the new trend introduced using different slabs. One-way ribbed slabs are commonly used in construction due to their efficiency in spanning long distances while maintaining a low overall depth and giving the least possible number of columns. The main limitation of slab design in the construction of a reinforced concrete structure is the span between columns; a greater span between columns necessitates more supported beams or increased slab thickness; these requirements lead to an increase in the structure weight due to other concrete and steel which make the structure more costly. On the other hand, any increase in the structure’s self-weight limits the horizontal slab’s span, increases the structure’s stress, and raises the inertia forces that must be resisted. Lightweight aggregate concrete has been effectively utilized for structural applications for a long time. The density of lightweight concrete (LWC) is sometimes more essential than its strength in structural applications. The dead load is reduced for structural design and foundations when the density is lower for the same strength level. Reinforced concrete ribbed slabs have become increasingly popular in industry construction as an alternative to solid slabs in building structures. The incorporation of steel fibers facilitates flexural softening, which takes longer than sudden brittle failure, indicating its ability to increase energy absorption and improve crack behavior. Designing structures requires materials with higher strength-to-weight ratios. Ribs and LWCs are two leading sustainable assets. The world is moving toward sustainability by reducing the amount of concrete used and the overall weight of the unit. Studies have shown that the drop in compressive strength was about 4.85–65.55%. The structural performance of lightweight fiber-reinforced concrete slabs is influenced by the concrete mix ratio, fiber type and content, reinforcement detail, and rib geometry. The study provides valuable insights into the properties and performance of key effects on the structural behavior of fiber-reinforced LWC-ribbed slabs. It provides recommendations for future research and advancement of sustainable building methods.

Concrete creep is the additional strain that develops in concrete under constant stress over time. In this study, lightweight concrete is created by entirely replacing coarse aggregate with pumice to reduce the concrete's overall weight. The research involves producing 18 cylindrical concrete test specimens with a diameter of 150mm and a height of 300mm. These specimens include three normal and three lightweight concrete samples for each 90-day creep test and three normal and three lightweight concrete samples for compressive strength tests on the 14th and 28th days. The variation in aggregate proportions affects the aggregate content and weight in each type of concrete, influencing their properties. This is evident in the creep curves for the lightweight concrete samples. Similarly, the differences in the creep curves for normal concrete samples are attributed to stress distribution during loading. The strain acceleration between normal and lightweight concrete under load remains similar until the final loading day at 90 days. However, lightweight concrete significantly increases creep value after prolonged loading, rising by 35.85%. In contrast, normal concrete exhibits a creep increase of 16.51% from the beginning of loading until the 90th day.