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This study evaluated the viability of biomass bottom ash (BBA) as a supplementary cementitious material (SCM) and sand substitute in cement-based materials. Physical and chemical characterization of BBA from eucalyptus forestry biomass and BBA from olive industry residues was performed. BBA underwent processing through grinding for SCM application and carbonation for sand substitution. Mortar mixtures were prepared with 25% ground BBA replacement for cement and 25% and 50% BBA replacement for sand, both carbonated and non-carbonated. Mechanical behaviour tested through flexure and compressive strength and water absorption at 28 days were assessed. Pulverised BBA enhance compressive strength of mortar compared to a conventional CEM II type cement and Carbonated BBA mortar mixtures improved 28-day compressive strength by 35-55% compared to non-carbonated BBA. BBA from eucalyptus forestry biomass, with pozzolanic activity, exhibited superior strength. The findings support the technical feasibility of BBA in cementitious materials, contingent on adequate processing.

The production of building materials impacts non-renewable resources through excessive raw material extraction and fossil resource consumption. This study investigates alternatives to Portland cement concrete by valorizing construction and demolition waste (CDW), including brick and reinforced concrete. The objective is to replace or eliminate clinker using geopolymers while incorporating CDW as recycled aggregates. Sustainable concretes were developed, such as geoconcrete with 0% clinker and 50% recycled aggregate, along with blends containing varying CDW percentages for structural applications. Results indicate that geopolymers with 100% ground granulated blast furnace slag (GBFS) achieve properties comparable to reference concrete. However, mixtures with recycled brick and concrete show lower strength due to low molarity and recycled aggregate usage. Elastic modulus increases with 100% GBFS but decreases by less than 10% with CDW. In beams, breaking moments reduce by up to 30% with 25% CDW, while brick-based mixtures demonstrate higher energy absorption.

This study focuses on the development of low-cement eco-concretes incorporating recycled concrete aggregates (RCA) and waste materials such as wood ashes, aiming to achieve a balance between sustainability and mechanical performance. Different concrete mixes were designed with varying cement content (240–290 kg/m3) and RCA replacement levels (25%–50% by weight). The materials used included II/A-LL 42.5 R cement, natural calcareous-silica aggregates, RCA from C30/37 concrete, wood waste ashes, and limestone filler. Experimental tests were conducted on fresh and hardened concrete, including workability, compressive strength, elastic modulus, carbonation resistance, freeze-thaw durability, and chloride penetration resistance. Results show that the mixtures with RCA demonstrated similar or better performance compared to conventional concrete, with C6 (using wood ashes from the burner) showing promising compressive strength and durability characteristics. The study demonstrates that these low-cement mixtures, using recycled aggregates and supplementary materials, can meet the durability requirements for sustainable infrastructure applications.

Ultra High-Performance Fiber Reinforced Concrete (UHPFRC) is known for its enhanced self-healing abilities, attributed to its low water-to-cement ratio, high content of un-hydrated cement particles, and multi-cracking pattern. This study investigates the effect of different fiber types and contents on UHPFRC self-healing. Two UHPFRC mixes were evaluated: one with 65/35 3D steel fibers in a dosage of 40 kg/m³ and another with short straight-shaped steel fibers (13/0.2) in a dosage of 160 kg/m³. The self-healing performance was evaluated through crack closure and water permeability. In addition, resistance to chloride penetration was evaluated in healed cracks. Pre-cracked disk specimens with cracks between 100-450 μm were subjected to two healing conditions: water immersion at 20°C and exposure to a humidity chamber (20°C, 95% RH). The mix with higher fiber content (U160) obtained superior crack closure and healing efficiency, particularly under water immersion. For cracks smaller than 150 μm, U160 achieved nearly complete healing, while U40 achieved limited healing efficiency. In addition, water permeability and chloride penetration tests revealed that the U160 mix offered higher resistance to water and chloride penetration, emphasizing the role of fiber content and crack pattern in improving the self-healing and durability of UHPFRC.

Two types of zeolites, coming from the total conversion of hazardous aluminum waste, have been considered in this study: NaP-type zeolite and LTA-type zeolite. Both zeolites are proposed to be used in cementitious mortars by substituting cement content in 5, 10 and 15%. The microstructure of both zeolites was characterized and they have certain interesting characteristics to be used as supplementary cementitious materials. The main fresh state characteristics and the mechanical performance of the fabricated mortars were also evaluated. The lower particle size of LTA-type zeolite promotes a filler effect that increases the fluidity of the mortar mixes and they also acts as nucleation sites for the cement hydrates, thus accelerating the cement hydration reactions. This acceleration of the cement hydration promotes the increase of the initial compressive strength of the mortars fabricated with this zeolite type. The higher silica content of NaP-type zeolite promotes pozzolanic reactions that significantly increase the long-term compressive strength of the fabricated mortars.

This review synthesizes prior research on size effect and autogenous self-healing in steel fiber-reinforced concrete (SFRC) under compressive fatigue. It explores the fatigue behavior of SFRC, focusing on fiber reinforcement’s role in post-cracking toughness, crack propagation, and fatigue endurance. The review demonstrates that larger SFRC specimens have reduced fatigue lives, attributed to increased elastic energy driving microcrack growth, aligning with classical size effect theory. Additionally, it highlights autogenous self-healing, where fatigue-induced microcracks release occluded water, promoting rehydration and calcium carbonate precipitation, which enhances residual strength. The interaction between size effect, fiber content, and self-healing is examined, offering insights into improving SFRC’s durability under cyclic loading. These findings have practical implications for designing SFRC structures subjected to compressive fatigue, such as wind turbine towers and railway slabs.

The present study evaluates the possibility of using a by-product of phosphate mines, such as red clay, as a precursor for the elaboration of acid geopolymers, using H3PO4 phosphoric acid (5M and 8M) as an activator. Considering the chemical composition of the clay, sodium aluminate (NaAlO2) was added as an aluminum corrector. To increase the reactivity of the precursor, the clay was thermally treated at 900°C for 2 hours. Pastes were prepared and characterized from the mechanical (compressive strengths), microstructural (BSEM/EDX and MIP), mineralogical (XRD and FTIR), and nanostructural (27Al, 29Si and 31P MAS NMR) point of view. The results showed that the type of reaction products is highly dependent on the chemical composition of the precursor and the acidic conditions. In addition, the presence of sodium aluminate improves the mechanical strengths in systems activated with 8M H3PO4.

Analysis has revealed that Moroccan coal gangue consists of silica, clays, and coal, making it a viable substitute for clay in clinker production. Our previous study demonstrated that the clinkering of a cement raw mix with 18.5% (wt) coal gangue and limestone produced a good Portland clinker. This clinker was close to that given by a cement raw mix of a cement plant, and which was taken as a reference-raw RR. The coal gangue contains around 8.8-11.8% coal, exhibits a calorific value of 3.77 MJ/kg and displays an exothermic effect of 67.3 J/g as determined by DSC analysis. This exothermic release is also observed in the LG cement mix. The objective of this study is to estimate the energy contribution of coal gangue in clinker production by comparing the thermochemical energy balances during clinkering up to 1450°C for the two clinker raw materials, LG and RR; our calculations indicate an energy gain of approximately 2.13%.

This study explores the use of two industrial residues: spent bleaching earth (SBE) and glass sediment (GS), as alternative raw materials in the production of ceramic materials from fired clay. The mixtures incorporating 0%, 10%, 30%, and 50% by weight of these residues, were examined. The impact of quantity and type of waste on product properties (density, water absorption, compressive strength, and thermal conductivity) was assessed against NTC 4205 standards. Incorporating 50% SBE reduced thermal conductivity by 35%, but increased porosity affected compressive strength. Glass sediment incorporation increased thermal conductivity but surpassed pure clay in mechanical behavior. The triphasic mix (20% GS, 10% SBE with lime) demonstrated optimal mechanical performance, meeting fired clay masonry unit standards. An eco-product prototype based on this mix was successfully manufactured, affirming that industrial waste is a viable alternative raw material, yielding ceramic materials with properties meeting or surpassing Colombian construction industry standards.

Waste waterglass foundry sand (WwFS) is a solid waste generated by the foundry industries that is commonly discarded in landfills and has urgent needs for disposal and recycling. Accordingly, this study suggests using WwFS as aggregates source for the preparation of alkali-activated slag mortars (AASM). Two different pre-wetting methods (24 h pre-wetting at 20°C and 1~6 h pre-wetting at 70°C) were used to treat WwFS and compared their performances with adding quartz sand and dried WwFS mortars. Compared to WwFS mortars without pre-wetting treatment, the compressive strengths of WwFS mortars containing WwFS pre-wetting in water at 70°C at 28d were increased by 1.3~10.0%, and the C-(A)-S-H average elastic modulus was increased by 16%. This study confirmed the feasibility of using hot water pre-wetted WwFS as the single aggregate source for AASM, which is important for the large-scale utilization of WwFS.

Autoclaved Aerated Concrete (AAC) is a lightweight and sustainable building material known for its thermal insulation and acoustic properties. However, its relatively low mechanical strength limits its use in load-bearing applications. This paper introduces the concept of incorporating unsaturated polyester resin (UPR) pins into AAC blocks to improve compressive and flexural strength of the material. Pin diameters of 4, 6, 8 and 10 mm were studied, oriented at 90° and 45° in relation to the AAC main plane. The effects of the UPR/AAC interface were analyzed through microscopy. The results point to a substantial increase in mechanical strength of the reinforced AAC, wherein smaller pins with orientation of 45° and 90° presented the best behavior under flexural (up to 298%) and compressive loading (up to 183%), respectively.

This study aims to present alternatives to reduce the demand of cement in concrete production based on particle packing concepts. Physical and mechanical characteristics of concretes, as well as the resistance to chlorides action were analyzed. The tests conducted in this study included compressive strength, chloride migration, capillary absorption tests and wetting and drying cycles in 1M sodium chloride solution. Mixtures containing limestone filler presented satisfactory results compared to the reference mixture with particle packing. Excellent results were obtained for concrete with cement consumption of 253.34 kg.m-3 in terms of compressive strength, binder index, capillary absorption and depassivation time of rebars, thus reinforcing the concept that partial cement replacement by limestone filler yields positive results in these properties. Worse results were obtained for concrete with a cement consumption of 161.86 kg.m-3, because it had a higher proportion of filler than cement. The electrochemical monitoring of the steel bars also shows that the packing of the aggregates was essential to delay the initiation of corrosion.

To inquire about the properties of concrete reinforced with polyvinyl alcohol (PVA) fiber (various fiber lengths and dosages), different experimental tests including mechanical property, cracking resistance, and chloride resistance were investigated. The overall performance of PVA fiber-reinforced concrete (FRC) was innovatively analyzed integrating mechanical indicators and crack resistance parameters. Furthermore, nuclear magnetic resonance (NMR) and scanning electron microscope (SEM) were selected to analyze the causes and mechanisms underlying the alterations in the performance of PVA-FRC. The experimental results demonstrate that the flexural strength, the crack resistance characteristic and chloride ion penetration resistance of PVA-FRC are significantly improved compared to ordinary concrete. Increasing fiber length plays a key role in flexural strength, compared with fiber dosage. Considering both mechanical properties and durability, PVA-FRC containing 0.25% volume fraction of 12 mm PVA fibers (F12-0.25) demonstrated optimal performance.

This study deals with the production of concrete with low CO2 emissions. For this reason, two materials, namely palm oil fuel ash (POFA) and limestone powder (LP), were used as mineral additions to replace conventional cement as much as possible. The results showed that concrete containing 60 wt% POFA could achieve the high strength requirements of ACI 363R from an age of 28 days. At a replacement level of 70 wt% of admixtures, the use of 10 wt% LP + 60 wt% POFA was a good mixture as it had the highest concrete compressive strength, had a minor effect on shrinkage strain and reduced heat generation by approximately 50% compared to cement concrete. Additionally, the use of POFA and LP is a good choice to produce environmentally friendly concrete, which can reduce the CO2 emissions of concrete by about 44–62% compared to cement concrete at similar strength.

This study explores the efficacy of Recycled Fine Powder (RFP) derived from construction and demolition waste as a sustainable substitute for Ordinary Portland Cement (OPC) as a Calcium (Ca) source in geopolymer mortar. Fresh properties of Geopolymer Mortar (GPM) were evaluated in terms of slump-flow, initial-final setting time, whereas hardened properties were evaluated in terms of Compressive Strength (CS), Water Absorption (WA), porosity, acid attack, and dry shrinkage at both ambient and heat curing. Results indicate that the RFP performs well in all mixes. However, mix C10R10 shows the overall best results, as 17% higher compressive strength was observed as compared to mix C20R0, which further increases to 88% when compared to mix C0R0. Thus, RFP provides sufficient Ca content as an activator in GPM.

This research focused on two objectives: (i) investigating the impacts of sediment substitution in the raw meal on the hydration and mechanical-microstructural properties of cement; (ii) assessing the reliability of CEMHYD3D code for modeling the properties of hydrated cement. The experimental results indicated that a maximum rate of sediment up to 7.55% had no impact on the formation of mineralogical phases of clinker, the hydration and mechanical-microstructural development of cement. The degree of hydration and strengths of cement made of sediment substitution were slightly higher than those of reference cement, whereas the critical diameter of pores of both hydrated cements was nearly identical. Comparing the modeling results with the experimental measurements showed good predictions for the degree of hydration, hydration heat as well as strength development. However, the formation of hemi-and mono-carboaluminate phases was not predicted in the model, and the porosity prediction was also limited to the capillary porosity.

This paper aims to establish an explicit crack bridging model that can link engineered cementitious composites (ECC) behavior from single fiber to single crack scale, which is great of designing ECC featuring pseudo tensile strain hardening and multiple cracks expanding by tailoring microstructure and materials selection. In this study, fiber bridging stress was divided into three parts including fiber bridging stress with no rupture, fiber debonding fracture stress, and fiber pullout fracture stress. Subsequently, the fundamental crack bridging model was emerged when fiber bridging stress with no rupture subtracted from the fiber rupture stress in debonding and pullout stage. Moreover, two-way pullout and Cook-Gordon effect were also considered to establish the complete model. It was found that the two-way pullout situation of polyvinyl alcohol (PVA) fiber has a significant influence on the crack opening width due to its slip hardening property, while the Cook-Gordon effect presents a faint crack width increment for PVA-ECC. However, the Cook-Gordon effect makes a significant contribution to the crack opening width of the composite produced by polyethylene (PE). This building intelligible model presents a better prediction for ECC through the comparison of experimental data or real average crack width in previous models, thus confirming the validity of this model.

The maintenance and rehabilitation of roads is becoming a key challenge in the pavement industry to decrease the consumption of natural resources. Microwave-assisted self-healing technology extends the life-service of asphalt pavements for roads reducing the need for fossil fuels over its lifespan and saving the use of natural resources. This technique takes advantage of the thermoplastic and dielectric properties of asphalt mixtures that allows cracks to be closed, hence, heal and restore the asphalt mixtures mechanical behaviour without implementing more invasive traditional maintenance operations like milling and replacing the pavement. A Life-Cycle Assessment was carried out to determine the potential environmental benefits of using this technology quantifying its potential environmental impacts. Different scenarios in which the heating energy and the addition of slag varies has been evaluated and compared with a conventional road. Results shows that this technology could decrease a significant number of environmental impacts over the lifecycle.

The objective of this study is to present a new method of reinforcing masonry using layers of mortar reinforced with short jute fibers. Mortars were produced with 0%, 2% and 3% jute fibers with cementitious matrices free of calcium hydroxide. The effectiveness of the reinforced mortar was evaluated through diagonal compression tests of hollow ceramic brick masonry prisms. The prisms were coated on both sides. The experimental results demonstrated that the diagonal resistance of the fiber system increased by 28 to 30% and presented greater resistance to elastic deformation during load application, with deformation coefficients 2 and 3 times greater for 2% and 3% of fibers, respectively. Therefore, jute fibers prove to be a sustainable and efficient alternative for masonry reinforcement applications, with maximum applied loads considerably higher than the unreinforced system, in addition to better crack control.

In this study, first, synthetic wollastonite microfiber (SWM) with a high aspect ratio (44:1) was produced with a special three-stage production method. Then, fly ash and ground granulated blast furnace slag-based engineered geopolymer composites (FA+GGBFS-based EGCs) were developed. SWM was used in different proportions instead of FA. The compressive strength of EGCs, changed in the range of 88.1-111.1 and 95.1-122.6 MPa at 7 and 28 days, respectively. Additionally, EGCs containing 6% SWM performed the best, considering both ‘‘increasing deformation capacity’’ and ‘‘maintaining the bearing strength by fiber bridging after crack’’, since they acted like a fiber owing to the acicular particle structure of SWM. Moreover, it can be said that the presence of the SWM mineral in the pore system, ensured pore discontinuities in the matrix because of its acicular particle structure. Consequently, the mechanical, durability and dimensional stability properties of EGCs improved with SWM.

This research investigated the influence of using chemically treated glass microparticles as a partial replacement for cement in Portland cement pastes and mortars. The microparticles were obtained by grinding glass waste into three different particle size fractions (< 75 µm, < 45 µm, and < 25 µm), treated with calcium hydroxide (CH), and characterized using SEM/EDS and a laser particle size analyzer. Samples prepared with the incorporation of glass were characterized using XRD, TGA/DTG, and SEM/EDS. The pretreatment with calcium hydroxide induced the formation of C-S-H with different morphologies on the surface of the particles, in addition to causing changes in particle size distribution due to the formation of agglomerates. The pastes prepared with treated particles had lower amounts of CH and higher levels of hydrated silicates. However, when indirectly measuring the pozzolanicity of treated particles through the compressive strength of mortars, no significant differences were observed in the strengths of mortars made with treated and untreated particles.

The aim of this research is to determine the effect of sodium hydroxide molarity 2M combined with variations in slag percentage, ratio of alkali activator to binder (Al/Bi), and ratio of sodium silicate to sodium hydroxide (SS/SH) on the transport properties of fly ash-slag-based GPC cured at ambient temperature. The result is increase in slag percentage and SS/SH ratio lead to a decrease in porosity, water absorption rate and chloride permeability. The alkali activator to binder (Al/Bi) ratio of 0.45 produces the lowest porosity, water absorption rate, and chloride permeability. The porosity, sorptivity, and chloride penetration depths of all GPC are lower than those of OPC. The recommended mix compositions for GPC that exhibit lower transport properties than OPC are GPC4 (slag 40%, SS/SH ratio 1.5, Al/Bi ratio 0.45); GPC5 (slag 50%, SS/SH ratio 1.5, Al/Bi ratio 0.45); and GPC7 (slag 30%, SS/SH ratio 2.0, Al/Bi ratio 0.45).

The paper analyses the degradation process of commercial ultramarine blue pigments in cementitious materials. For this purpose, two commercial pigments (with and without a protective coating) in different solutions and cement pastes are studied incrementally. The results show that pigment degradation occurs due to an ion exchange phenomenon; during hydration high ion contents are released, calcium and potassium being the most aggressive for the pigment. Calcium distorts the unit cell; between the sodium of the pigment and the potassium in the medium a cation exchange phenomenon takes place. Both processes lead to the diffusion of sulphate and sulphide ions from the pigment to the medium causing loss of colour and the formation of ettringite.

The aim of this paper is to evaluate the influence of a crystallizing chemical admixture on precast micro concretes with two water contents (7% and 11%, by dried mass) and two different conditions of exposure. Thus, precast micro concretes with a composition of 1:3 (cement: fines) with and without crystalline chemical admixture were evaluated on compressive strength (at the age of 28 and 154 days) and water absorption by immersion (at the age of 154 days). Statistical analysis showed that the only significant factor was the effect of the water content on the compressive strength. Besides that, the most significant factors for the water absorption and voids index properties were the water content, followed by the exposure conditions, and the interaction between the water content and the presence of the chemical admixture. The crystalline admixture was insignificant in the conditions of this research.

This research investigated the bond properties at high temperatures and with hybrid fiber addition between basalt fiber reinforced polymer (BFRP) bars and hybrid fiber-reinforced concrete (HFRC). The tensile strength and appearance morphology of BFRP bars were analyzed. Used scanning electron microscopy (SEM) to examine the microscopic morphology and used the bond-slip constitutive model to fit the bond-slip curves. When BFRP bars after exposed to 300 °C, their tensile strength dropped by 42%. With the increasing temperature, the bond strength and stiffness of normal concrete (NC) specimens decreased by 27.3 % and 67.5 %, respectively, while HFRC specimens decreased by 20.8 % and 55 %, respectively. Hybrid fibers increased the bond strength and stiffness of HFRC specimens by 27.1 % and 49.1 %, respectively. The best fitting models were the Malvar model and the Continuous Curve model.

This paper presents an experimental study on a set of 30 specimens, tested on three-point bending, divided into two categories. With the insertion of geogrids and cathodic emulsions, the first category consists of 14 prismatic beams and the second of 16 pre-cracked and reinforced slab specimens. In situ tests were carried out using a heavy deflectometer (HWD) on a flexible runway of an airfield located in the city of Ouragla (800 km south-east of Algiers), before and after its reinforcement. This work showed, with a numerical calibration, that the geogrid with emulsion, improves the displacements and the stresses approximately 30% and increases the modulus of elasticity and the modulus of rupture (MOR) by 60% and 20%, respectively. The damping coefficient (k) can reach the value of 2 to 5, which increases the longevity of a reinforced flexible pavement.

The study explores the potential of recycling construction and demolition waste into recycled coarse aggregates (RCA) to decrease waste generation and carbon footprint, using a standard compacting effort to calculate compressive strength and particle packing density in a specific cylindrical volume. This study investigates the impact of RCA on concrete’s workability, compressive strength, flexural, split tensile, drying shrinkage, electrical resistivity, rapid chloride penetration, and microstructural characteristics using XRD, SEM, and EDAX. Test findings showed that increasing the replacement percentage beyond the optimum value (RCA 25) had detrimental effects on the strength and microstructure of the concrete. RCA 25 has a higher compressive, flexural, and split tensile strength in the order of 11.56%, 3.06%, and 5.17% respectively compared to reference concrete, as well as 5.23% increase in drying shrinkage, 8.79% higher electrical resistivity, and 4.68% higher resistance to chloride penetration than reference concrete.

Rice husk residues are generated within the rice industry. In this research, the environmental impact of the use of rice husk ash is evaluated as a replacement for cement in the production of concrete in the city of Ibagué (Colombia). The environmental criteria of cement and concrete production alternatives were evaluated through life cycle analysis methodology, using SimaPro 9.3.3 software and the Recipe 2016 Midpoint (H) evaluation method. The economic cost of each of these production alternatives was included. To carry out the study, surveys and interviews had to be undertaken with rice-producing plants, aggregates, cement and concrete plants in Tolima. It was corroborated that rice husk ash (RHA) generated during the rice husk (RH) gasification process for electricity and heat production was beneficial from an environmental and economic perspective when it was used in cement and concrete in the city of Ibague (Colombia).

The use of recycled aggregates instead of natural aggregates used in concrete reduces environmental pollution and concrete costs. Recycled Asphalt Pavement (RAP) aggregate used as recycled aggregate has a lower water absorption than natural aggregate due to its bituminous structure, which reduces the water requirement of fresh concrete. In this study, it was aimed to determine the optimum use of RAP particles as aggregate in concrete for read pavements and to determine their durability properties. For this purpose, RAP was used instead of crushed stone aggregate used in concrete road construction. RAP was used by replaced aggregate 0%, 25%, 50% and 100% of the crushed stone aggregate used on the concrete road. The dose of the produced concrete was 350 kg/m3 and the water/cement ratio was kept constant as 0.45. The fresh workability and air content of concretes containing RAP were determined. Compressive strength, splitting tensile strength, electrical resistivity value, accelerated corrosion test of hardened concretes were subjected to corrosion resistance, water absorption and porosity percentage, acid resistance, ultrasonic pulse rate and Scanning Electron Microscope (SEM) and X-ray Diffractometer (XRD) analyzes were determined. In the experimental results, it has been observed that the use of RAP ratio of 25% and 50% remains within the limit values for concrete pavement. It is recommended to be used on reinforced concrete roads that will be exposed to adverse environmental conditions with its high corrosion resistance, thanks to its anti-corrosion feature.

This article presents the experimental outcomes of the shear strength and microstructural characteristics of high-volume fly ash self-compacting concrete (HVFYA-SCC) containing recycled concrete aggregates and coal bottom ash as partial replacements for natural coarse aggregates and natural fine aggregates. A total of ten numbers of mixes were produced, including HVFYA-SCC made without recycled concrete aggregates and coal bottom ash (as control) along with HVFYA-SCC mixes made with recycled concrete aggregates (from 25% to 50%) and coal bottom ash (from 10% to 30%). The compressive and shear strength of the HVFYA-SCC mixes were improved by 7% and 4%, respectively, with the incorporation of 20% coal bottom ash and 25% recycled concrete aggregates after 120 days of curing. On the other hand, scanning electron microscopic analysis revealed that incorporating coal bottom ash exhibited the pozzolanic reactions with fly ash densified the binder-aggregate matrix of the resulting HVFYA-SCC.

The application of various Fiber Reinforced Polymer (FRP) composite materials is very widespread in the world. The use of recycled materials in concrete, can improve some of the mechanical properties of concrete. In this laboratory research, the behavior of reinforced concrete beams with composite rebars with glass fibers made of concrete containing recycled materials such as glass, rubber and micro-silica with different mixing plans has been investigated. These mixing plans are such that recycled glass and rubber aggregates have replaced a percentage of fine and coarse concrete aggregates, and glass powder and micro-silica have also replaced a percentage of concrete cement. The results showed that the replacement of coarse rubber, glass powder, and micro-silica in concrete materials increases the bending strength and ductility of concrete beam. In examining the microstructure of concrete by Scanning Electron Microscope (SEM) the adhesiveness of the rubber Interfacial Transition Zone (ITZ) in concrete was suitable.

This study presents the preparation of steel-fiber reinforced concretes (SFRCs) using straight navicular fibers with annular-sector-shaped sections and corrugated fiber with rectangular-shaped sections, respectively. The flexural and splitting tensile strengths of both the respective SFRCs increase with increasing fiber volume fraction, whereas their compressive strengths initially increase, then decrease, and then increase again. For the same fiber volume fraction, the mechanical properties of the navicular fiber-reinforced concrete are superior to those of the corrugated fiber-reinforced concretes. The introduction of steel fiber changes the failure mode of the plain concrete during bending from a typical brittle mode to a bimodal ductile failure mode. As compared to the corrugated fiber, the navicular fiber has stronger interface bonding to concrete and a higher friction resistance to fiber sliding and subsequent pullout. Furthermore, navicular fiber has a higher load-bearing capacity, which makes it more favorable for improving the mechanical properties of plain concrete.

High water absorption is a typical characteristic of recycled coarse aggregate and is often used to explain the loss of performance of concrete when replacing natural coarse aggregate with recycled coarse aggregate. Extensive attention has been paid to the mean value of the water absorption of recycled coarse aggregate, but not to the standard deviation. This paper aims to assess whether recycled coarse aggregates with the same mean water absorption but different standard deviations will perform equally in high-performance concrete (HPC). The resulting HPC mixtures exhibited very similar compressive strength. Even so, it was hypothesised that as the standard deviation of the water absorption of recycled coarse aggregate increases over a wide range, the compressive strength of HPC will first increase due to local variations in the water/cement ratio, then decrease due to the presence of weak particles, and finally remain constant due to the role of the surrounding new mortar.

In this study is explored the use of construction and demolition waste as fine aggregate in mortars. The addition of nano-graphene oxide (0.1%wt) has also been evaluated. Tests were conducted to determine their density, humidity content, water absorption capacity and open void porosity (using water absorption) and the micro and nano-porosity using Hg intrusion and N2 absorption techniques, as well as their flexural and compressive strength and resistance to acid attacks. The mechanical properties of mortars manufactured with standard sand were better (30%) than made with waste aggregate. Mortars with both aggregates can be classified as M20. Nano-Graphene oxide acts as a filler, reducing the volume of macro and micro pores, thereby increasing the mechanical performance, especially when recycled aggregates are used (30% the flexural strength for recycled aggregates and 4% for standard sand). The addition of nano-graphene oxide reduces the transmission channels of acid within mortar.

Limestone Calcined Clay Cement (LC3) Technology is a low carbon cement that combines limestone, calcined clay, and clinker, aiming to reduce CO2 emissions by 40%-50% during production. In this study, large-scale investigations were conducted to explore LC3 as a potential substitute for conventional cement (CC). Mechanical and durability tests were performed on LC3, comparing results with CC and Pozzolana Cement (PC) concretes. The findings revealed that LC3 concrete exhibited promising early-stage strength similar to CC concrete. However, at 90 days, LC3 showcased a 10% higher strength compared to CC concrete. Additionally, LC3 displayed a remarkable 45% increase in resistance to moisture ingress, indicating improved durability over CC concrete. These results highlight the efficacy of low carbon cement in developing ternary blended cements that offer early strength and enhanced durability, making it a viable eco-friendly alternative in the construction industry.

This study aims to evaluate the effect of RCP from a precast concrete plant on rheological and mechanical properties of cementitious pastes. In the study, Portland cement was replaced by RCP in 10, 20, and 30% (in mass). The hydration kinects of cement with RCP was studied through isothermal calorimetry. The fresh properties were assessed using mini-slump test and rotational rheometry. The mechanical properties were evaluated through compression tests and the microstruture was studied using Scanning Electron Microscopy. RCP reduces fluidity of the pastes, by increasing both yield stress and plastic viscosity. The addition of RCP accelerates the hydration of cement, while reducing the released heat. RCP also reduces the compressive strength and elastic modulus of the pastes. The use of RCP as partial substitute for cement is viable, due to its size distribution and specific surface area.

The energy deficiency in rural housing in the Andes of Peru is recurrent. In this context, local and low environmental impact materials present an opportunity. This research evaluated the properties of five panels composed of totora and gypsum for ceiling applications. Firstly, the physical and durability properties were obtained. Then, impact and fire resistance were evaluated. Finally, thermoacoustic properties were assessed. The results showed a moisture level of 10.25%, water absorption of 354.85% which is considered high, and a dry density of 292.84 kg/m3. Adequate durability to fungus with resin on both sides. The panels’ fire resistance is superior to 60 minutes, with a safe impact criterion for 10 N and a functionality criterion for 5 N. The average values for the panels were 0.061 W/m·K for thermal insulation and 0.54 for NRC. Therefore, it is possible to produce an insulating material for thermoacoustic improvement.

This paper investigates the use of Na2CO3 as an alkaline activator on the durability of the alkali-activated slag (AAS) mortar toward sulfates and acids. The behavior of this binder in these aggressive environments is compared to those of slags activated with Na2SiO3 and NaOH. In addition, the setting times, workabilities, mechanical properties and drying shrinkage were evaluated. The AAS had superior workabilities, faster setting times and higher shrinkage rates than the Portland cement (PC). Increases in the activator dosages had positive effects on the mechanical strengths of the materials. Na2SiO3 was the best activator in terms of strength development, but it led to much higher shrinkage. The AAS showed less expansion and lower weight losses than the PC when exposed to sulfate and acids, respectively. The Na2CO3-AAS exhibited less shrinkage and higher resistance to sulfuric acid than the other activators, but the mechanical strength seen at early ages was low.

The main aim of this work is to study two relevant experimental setups designed for studying shear fracture and see if any of them allows studying the evolution of fracture under Mode II conditions, not only inducing a shear stress state at the onset of fracture. Two tests have been selected, a standardised test described by a Japanese standard, here referred to as the JSCE test, and the push-off test. These tests have been carried out on fibre-reinforced gypsum specimens with increasing proportions of polypropylene fibres and monitored by means of digital image correlation (DIC). The results show that fracture under Mode II conditions is relatively easy to induce with both tests, but once fracture begins, it is extremely difficult to induce a fracture process under Mode II. In general, Mode II has an important role at the onset on fracture, but Mode I predominates afterwards.

Bond deterioration in reinforced concrete (RC) structures is frequently caused by aging, environmental factors, overloading, or poor design. This deterioration may cause the structure to lose its aesthetic, and eventually collapse. The behavior of structures that exhibit bond deterioration is poorly understood and inadequately maintained. The response of RC structures exhibiting bond loss under tension load is presented in this paper. In order to comprehend the impact of bond loss in RC composite, the RC system was first built for a pullout. It was then expanded to the nib corner of RC dapped end beams. Additionally, the system was analytically examined using 3-dimensional FEmodel. The bond loss created a weak zone with internal cracks parallel to the bar’s axis. The nib section separated from the full depth of the dapped end, while the hanger reinforcement resisted the diagonal tension cracks. The dapped section must therefore be given more consideration during monitoring and maintenance.

In this study, the clogging mechanism of pervious concrete was evaluated using three different cloggers such as, Sand (S), Clay (C), and combination of sand and clay (S &C). The clogging mechanism was performed through falling head permeability apparatus, using clogger sediment load at the rate of 50, 150, and 200 grams in repetitive clogging cycles. It was observed from the results that combined (S & C) clogger shows overall critical results of clogging as 80% of the clogging was seen in 3 to 4 cycles. Moreover, it was observed from the results that pervious concrete mix made with R- type of aggregate gradation shows optimum compressive strength of the order of 8.6, 15.9, and 17 MPa at 7, 28 and 56 days of curing. Furthermore, the visual inspection test shows that clogging by clay clogger shows an even distribution of sediment on the whole length of the sample.

The design of render-mortars from construction and demolition waste (CDW) was evaluated. Fine aggregates from red-clay-brick waste, mortar and concrete waste were used, together with recycled expanded-polystyrene (EPS) as lightweight filler. Mixes composed of 70%-recycled aggregates, and 30% consisting of a matrix of Portland cement were produced. Characterization tests were conducted on the physical, mechanical, thermal, and acoustic properties. The render-mortar A4, A7 and A9 can be classified according to compressive strength results as CSI-W0 for interior use under standard UNE-EN-998-1. The A7 mortar, with the best physical and mechanical results, contained 21% EPS, 17.5% brick waste and 17.5% mortar waste. Mix A4 obtained the lowest thermal conductivity, 0.12 W/m·K - a reduction of 79% compared to the commercial-mortar AC1. The acoustic absorption properties were also enhanced by the incorporation of EPS, such that the A4, A7, and A9 mixes were identified as Absorbent for the frequencies of 2000 Hz and 4000 Hz.

The traceability of granite blocks consists in identifying each block with a finite number of colour bands that represent a numerical code. This code has to be read several times throughout the manufacturing process, but its accuracy is subject to human errors, leading to cause faults in the traceability system. A computer vision system is presented to address this problem through colour detection and the decryption of the associated code. The system developed makes use of colour space transformations and various thresholds for the isolation of the colours. Computer vision methods are implemented, along with contour detection procedures for colour identification. Lastly, the analysis of geometrical features is used to decrypt the colour code captured. The proposed algorithm is trained on a set of 109 pictures taken in different environmental conditions and validated on a set of 21 images. The outcome shows promising results with an accuracy rate of 75.00% in the validation process. Therefore, the application presented can help employees reduce the number of mistakes in product tracking.

Efforts are made to alleviate thermal problems in buildings. The use of thermal mortars for coating with vermiculite as aggregate is used for this purpose, but the use with mineral additions is still scarce, especially the rheology through squeeze-flow. Thus, it was aimed to evaluate the behavior in fresh, hardened state and in the thermal conductivity of these mortars. Mortars containing Portland cement, lime, vermiculite, sand, and additions of metakaolin or ceramic brick waste, in the proportion of 1:1:6 (Cement: Lime: Sand), were evaluated. The sand was replaced by vermiculite in 40%, and the additions added in the proportion of 20% to the cement mass, and the water content determined with the spread obtained on the consistency table. Mixtures containing 20% mineral addition and 40% vermiculite proved to be feasible, reaching minimum values according to the respective standards.

In this study, a novel technique for producing synthetic aggregates using industrial by-products was experimentally investigated. Taguchi method is used to identify the optimum mix design proportion to develop durable synthetic aggregates. For this, different combinations of quaternary binders including ordinary Portland cement, ground granulated blast furnace slag, metakaolin, and lime powder was used. The obtained results revealed that the synthetic aggregates prepared with optimized mortar mix enhanced the compressive strength by 5.9%. Then the performance of synthetic aggregates was evaluated based on their mechanical and durability properties. Microstructural properties of the produced aggregates were examined. The results showed that optimum mix is highly effective than control mix. The manufactured synthetic aggregates are in accordance with the ASTM C 330 standard requirements. Therefore, our study contributes to the advancement in the sustainability by developing a method for producing synthetic aggregates from industrial byproducts.

The use of high percentages of substitution of Portland cement by pozzolans can provoke the total consumption of portlandite. The present research proposes the study of ternary systems of Portland cement (PC), fly ash (FA), and hydrated lime (CH). After 180 days of curing, the mortar with 50% substitution of PC by FA obtained 65.9 MPa versus the mortars with an addition of 20% of CH and control mortar (100 PC) that obtained 69.9 MPa and 76.7 MPa respectively: this behavior is very positive value considering that tested FA containing mortars had a 50% of Portland cement. Regarding the effect of the amount of extra hydrated lime on durability issues, the evolution against carbonation of PC-FA and PC-CH-FA mortars was studied: the reduction of carbonation velocity was around a 37% for the mortar with CH respect the PC-FA mortar.

The paper shows a comparative study of the influence of whitening additives (kaolin, TiO2 and СаСО3) on the production of decorative alkali-activated slag cement and mortars with a degree of whiteness of at least 70%; as well as their influence on the structure formation and evolution of physico-mechanical properties. According to results obtained, kaolin provides chemical bonding of Na+ into insoluble zeolite-like compounds; and CaCO3 densifies the structure and reduces shrinkage deformations. At the early stages of hardening (up to 7 days), the additions of kaolin and calcite, due to their significant amount (15 and 24%), reduces the compressive strength of the cement paste; nevertheless, at later ages (until 90 days) the difference in strength almost disappears. The high colourfastness and weather resistance of pigmented cements under the influence of ultraviolet radiation and freeze/thaw cycles has been established. A comparative assessment of the economic efficiency has shown that СаСО3 is the best cost-effective additive.

This work aims to obtain parameters of thermal performance of various types of plaster blocks for vertical sealing. The methodology consisted of making test elements with 8 types of plaster blocks, in addition to plasterboard of different densities. Thermal resistance, transmittance, capacity, and delay were calculated, according to the Brazilian standard NBR 15220. Thermal behavior tests were carried out with controlled heating through a heat source, digital thermometer, infrared thermography, and an instrumented thermal chamber developed for this work. The experimental results corroborated with the trend indicated by the calculated parameters. The massive and hollow blocks of 100 mm had the best results followed by the 76 mm hollow blocks. The 50- and 70-mm massive blocks were among those with the worst thermal behavior. The study through the thermal chamber and real test elements associated with the normative methods allowed the practical verification regarding the thermal behavior of the components.

Nowadays, it is imperative to reduce the energy bill in order to contribute to a more sustainable planet. In this sense, the use of materials that contribute to the energy efficiency of buildings is a very important contribution to achieve this goal. Mortars incorporating phase change materials (PCM) can make an important contribution to this end, due to its thermal storage capacity, increasing the energy efficiency of buildings. In this work several mortars with different PCM contents were developed, using different binders (cement, aerial lime, hydraulic lime and gypsum). The aim of this study was to apply data mining techniques such as artificial neural networks (ANN), support vector machines (SVM) and multiple linear regressions (MLR) to forecast the compressive and flexural strengths of these mortars at different exposure temperatures. It was concluded that ANN models have the best predictive capacity both for compressive strength and flexural strength. However, the SVM models have a flexural strength forecasting capacity very close to ANN models.