The present investigation reviews some of the recent research work focusing on developing the use of ultra-high-performance geopolymer concrete (UHPGC) with metakaolin (MK) as a binder, which garnered significant interest due to fulfilling the growing need for durable, cost-effective, and environmentally sustainable construction materials, as it has substantial advantages, including the capacity to generate superior thermo-mechanical properties and durability with less of an adverse environmental effect where materials are used that reduce carbon dioxide emissions (CO2), and studying the effect of its inclusion with fly ash (FA), ground granulated blast furnace slag (GGBFS), and silica fume (SF). Also, this review examines the impact of incorporating alkali activators, which are mixing solutions of sodium hydroxide (SH) and sodium silicate (SS), and powdered waste materials as replacement materials for aggregates and cementitious materials-specifically basalt waste powder (BWP), marble waste powder (MWP), glass waste powder (WGP), and granite waste powder (GWP)-into MK-based UHPGC. These waste powders, generated from industrial by-products, provide an ecological approach to enhance the characteristics of concrete while decreasing waste. The most noticeable improvement in mechanical performance among the materials examined is shown by basalt waste powder, especially in terms of compressive and flexural strength (CS, FS). This enhancement is attributed to its unique mineral composition and pozzolanic activity, which refine the microstructure and strengthen bonding within the concrete matrix. This review discusses the limitations and potential optimizations for incorporating these waste materials, positioning metakaolin-based UHPGC as a sustainable and high-performance alternative in construction. Future research should address long-term durability, performance consistency, and the establishment of standards for using waste powders in geopolymer concrete formulations. The creation of ultra-high-performance geopolymer concrete has received relatively little attention, even though several studies in the field of geopolymer technology have been conducted.

Raw materials of concrete are one of the main pollution resources. Sustainable concrete is one of the significant solutions that can be used to reduce carbon emission. This study aims to use volcanic ash (VA) as a supplementary cementitious material (SCM) for producing sustainable concrete. The effects of VA on the properties of steel fiber reinforced concrete (SFRC) are evaluated. The fresh and hardened concrete's characteristics of steel fiber volcanic ash concrete (SFVC) is presented and assessed. Slump test, compressive strength, splitting tensile tests, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Fourier transform infrared (FTIR) spectrophotometry are used to investigate the effect of VA concrete performance. Five groups of SFVC were prepared using sixteen different mixes; 0 %, 2.5 %, 5.0 %, and 7.5 % of VA were used as a partial replacement of cement with 0, 0.5,1.0 %, and 1.5 % of steel fiber (SF). The findings demonstrated that concrete sustainability could be improved by employing VA as a partial replacement for cement, resulting in improved mechanical performance with a slight reduction in workability. The optimum mechanical and microstructure properties of SFVC were achieved with the incorporation of 5 % VA instead of cement with 1 % steel fiber, at age 28 days. The increase in compressive strength and tensile strength up to 25 % and 31 %, respectively. The employing of VA as a SCMs material resulted in better ITZ between aggregate and cement mortar and exhibited a dense surface with less pores compared to control mix.

The purpose of this research is to investigate the impact of hybrid micro and macro polypropylene fibers (PPFs) on the mechanical characteristics and microstructure of high performance concrete (HPC). Seven concrete mixes with different contents of hybrid polypropylene fibers were tested. The tests included the slump test, compressive and flexural strength, resistance to elevated temperatures, and concrete microstructure. Compared to the control mixture, introducing macro and micro polypropylene hybrid fibers to HPC mixes dramatically enhanced the flexural and compressive strength of concrete while lowering workability. HPC compressive and flexural strengths decrease as temperature rises, nevertheless, the strength loss rate was lowered with the use of hybrid PPFs. In addition to increasing the compressive strength by 14.6%, 14.28%, and 11.4% at ages 7, 28, and 56 days, respectively, the combination of 0.75 kg/m3 micro and 5 kg/m3 macro PPFs also raised the flexural strength by 41.9% at age 56 days, and the highest residual compressive and flexural strength of concrete after being exposed to 200, 400 and 800 °C was achieved, the residual flexural and compressive strength up to 45.6%, and 64.3%, respectively, of the initial strength after exposure to 800 oC. The network structure generated by macro and micro polypropylene fibers in the matrix has been well demonstrated by microstructural analysis. The incorporation of hybrid polypropylene fibers prevents capillary cracks in concrete and probable disintegration between aggregate and cement paste.

One of the most important challenges in developing the concrete industry is to use sustainable materials that are able to improve concrete properties. Magnetized water (MW) is a type of water that can replace tap water (TW) in conventional concrete and enhance its mechanical properties. However, the performance of MW in geopolymer concrete has not been well investigated up to now. The goal of this study is to measure the effect of using an alkaline activator (AA) made of MW on the mechanical properties and durability of fly ash (FA)-based geopolymer concrete. The AA was a mixture of sodium hydroxide (SH) solution and sodium silicate (SS) solution. Eighteen geopolymer concrete mixes were tested for several fresh, hardened, and durability properties. Of these mixes, nine were prepared with AA made of MW and the other nine were the same but prepared with AA made of TW. The preparation of MW was simply carried out by passing TW across permanent magnets of 1.6 Tesla, and then 1.4 Tesla intensities for 150 cycles. The MW-based AA properties were analyzed and compared to those of the conventional TW-based AA. Several mechanical and durability properties were measured. Scanning electronic microscopy (SEM) analysis was also conducted on selected mixes. The outcomes of the hardened concrete tests demonstrated that while using MW to prepare AA solution contained SH with a molarity of 16 M, an SS/SH ratio of 2, an AA/C ratio of 0.4, a W/C ratio of 10%, and a curing temperature of 115 °C could display the best outcomes in this study when used in geopolymer concrete. Using MW in a geopolymer concrete AA could increase its slump by up to 100% compared to that made of TW. Using MW in the AA enhanced the compressive strength by up to 193%, 192%, and 124% after 7, 28, and 56 days, respectively. The SEM analysis showed that using MW clearly enhanced the surface morphology of geopolymer concrete. The proposed geopolymer concrete made using the MW-based AA in this study sheds the light on a new class of eco-friendly concrete that could possibly be used in many structural applications.

Due to its high cement content, ultra-high performance concrete (UHPC) is not an eco-friendly material. Utilizing alternative materials as a replacement of cement could improve UHPC's sustainability and reduce environmental impact. This study intends to examine the impact of using different alternative filler materials such as quartz powder (QP), limestone powder (LP), granite powder (GP) and basalt powder (BP) along with silica fume (SF) as a cement replacement on mechanical characteristics and durability of UHPC. The total powder content composed of 60% cement, 20% SF, and 20% filler materials (QP, LP, GP, and BP). Mixture design method in Minitab program was used to design concrete mixtures. Flowability, compressive strength, water permeability, rapid chloride permeability, sulfate resistance and concrete microstructure were the tests performed on the concrete mixtures. Utilizing QP, LP, BP, and GP as a partial replacement of cement in the production of UHPC resulted in significant negative impact on concrete flowability. UHPC with low environmental impact and compressive strength more than 120 MPa with higher durability could be produced using QP, LP, BP, and GP as a replacement of cement. Mixture composed of 711 kg/m3 cement, 237 kg/m3 SF, 118.5 kg/m3 QP, 118.5 kg/m3 BP, 1017 kg/m3 sand, 142.2 kg/m3 water, 31.3 kg/m3 super plasticizer, and 156 kg/m3 steel fibers achieved the highest compressive strength at age 7, 90, 180 days, the strength were 85 MPa, 123 MPa, and 126.1 MPa respectively. The findings demonstrated the development of a strong relationship between responses and constituent materials in predicting and optimizing compressive strength of UHPC, enabling construction implementers to obtain mixture design proportion to obtain UHPC with certain desirable properties using the proposed models without resorting to making experimental mixtures using a trial-and-error method, which consume time and effort.

This research aims to study the effect of replacing up to 100% of recycled coarse aggregates with heavyweight aggregates. In addition to the effect of adding heavyweight aggregate slag on the efficiency of shielding against radiation and on the mechanical physical properties and elevated temperature of heavyweight high-strength concrete (HWHSC). In this investigation, HWHSC mixtures incorporate lead slag (LS), copper slag (CS), and steel slag (SS) as coarse aggregate. Recycled heavyweight coarse aggregates are added to concrete mixtures at volume ratios of 0%, 25%, 50%, 75%, and 100%. Slump test, compressive strength, flexural strength, tensile strength, elastic modulus, and bulk density tests were carried out. Three different gamma-ray energies at 137Cs 662, 60Co 1173, and 60Co 1332 (keV) sources were used to evaluate the mass attenuation coefficient, linear attenuation coefficient, half and tenth-value layer, and mean free path. To evaluate the impact of elevated temperature on density, compressive strength, and radiation shielding properties, concrete mixtures were exposed to 22 degrees C, 300 degrees C, 500 degrees C, and 800 degrees C. Compared to basalt-based concrete, heavy-weight concrete (HWC) incorporating LS, CS, and SS coarse aggregate has a significantly higher density. The results show a good effect of recycled heavyweight coarse aggregates on fresh, mechanical, and radiation-shielding properties. The density of the developed high-strength concrete (HSC) mixes ranges between 2400 and 3370 kg/ m3, and the increase in recycled heavyweight coarse aggregates replacement ratio up to 75% increased all mechanical characteristics of HWC mixtures. Using LS as a replacement of basalt by 75% resulted in the highest compressive strength, splitting tensile strength, flexural strength, and elastic modulus of 105.8 MPa, 14.2 MPa, 19.5 MPa, and 45.76 GPa, respectively. Compared to basalt, LS, CS, and SS eliminate the impact of elevated temperatures on HSHWC strength. The best radiation protection properties were achieved with the complete replacement of basalt by LS.

This study investigates experimentally the impact of magnetized water (MW) on the fresh and hardened characteristics of concrete. Five types of MW are produced using magnetic fields of 1.4 and 1.6 Tesla for treating water with 100, 150, and 250 cycles. The concrete properties are assessed using the slump test, compressive strength test, scanning electron microscopy (SEM) analysis, energy dispersive X-ray analysis (EDX), and Fourier transform infrared spectrophotometry (FTIR). Furthermore, the chemical-physical characteristics of tap water (TW) and MW are evaluated. The results showed the magnetic field intensity has a significant impact on the magnetization effect; the best magnetizing conditions were found when TW was exposed successively to magnetic fields of 1.6 T and 1.4 T for 150 cycles. In addition, 150 MW cycles can be used to improve the compressive strength and workability of concrete by 40% and 17%, respectively. pH, total dissolved solids, and electrical conductivity improved by 15%, 17%, and 7%, respectively, when using MW. Additionally, MW can be used to enhance cement hydration chemical processes and made concrete's structure denser.

The incorporation of construction and demolition (C&D) waste in concrete production has gained great importance toward sustainability, especially in geopolymer concrete. In this study, ground granulated blast-furnace slag (GGBFS) and fine aggregate of normal geopolymer concrete were partially replaced by clay brick powder (CBP) and fine clay brick (FCB) derived from C&D waste, respectively, aiming to produce high-strength geopolymer concrete (HSGC). Fly ash (FA) was also used as a partial replacement for GGBFS in normal geopolymer concrete. Twenty HSGC mixtures were designed using the response surface methodology with three variables, including CBP (0–25%), FA (0–25%), and FCB (0–50%). The performance of the proposed HSGC mixtures was assessed by measuring several mechanical and durability properties. In addition, a variety of physicochemical methods, including X-ray fluorescence spectroscopy, X-ray diffraction, and scanning electron microscopy, were used to examine the mineralogical and microstructural characteristics of the control and the developed mixtures. The findings revealed that the compressive, splitting tensile, and flexural strengths of the HSGC made with C&D waste ranged from 38.0 to 70.3 MPa, 4.1 to 8.2 MPa, and 5.2 to 10.0 MPa, respectively. The results also indicated that the incorporation of FA is an essential parameter to eliminate the negative impacts of C&D waste addition on concrete workability. The optimal proportions for the HSGC were 5% for CBP, 5% for FA, and 40% for FCB, which were determined to generate the optimized HSGC with the highest mechanical performance, according to the verified models and optimization findings. The physicochemical analyses showed that the thick amorphous geopolymeric gel predominated the nonporous structure of the optimized HSGC, which had good mechanical characteristics. Furthermore, the anti-carbonation performance and freezing resistance of the optimal HSGC increased by 17.7% and 14.6%, respectively, while the apparent porosity decreased by 8.4%.

This paper aims to fabricate and optimize eco-sustainable cement brick using different sizes of clay brick waste (CBW). The prime input factors of mixtures were clay brick powder (CBP) as a binder, fine-clay brick (FCB) as a fine aggregate, and coarse-clay brick (CCB) as a coarse aggregate, whereas the compressive strength was the main response of the generated eco-sustainable bricks. This was accomplished by utilizing the central composite design (CCD) and Response Surface Methodology (RSM) with Minitab-19. Twenty mixtures with CBW were generated and experimentally evaluated utilizing CCD concept in RSM. A multi-objective optimization approach was applied to obtain the optimum results for the input parameters. Based on an experimental program, the optimum mixtures were selected to investigate the physical and durability properties of the produced brick. The SEM test was also performed to determine the effect of the CBW particles on the microstructure of the brick. The life cycle assessment of mixtures is also performed in terms of global warming potential. The optimization showed that the input components CBP, FCB, and CCB had average optimum values of 21%, 0%, and 9.09%, respectively. The experimental results showed that employing CBW yields a durable and high freeze-thaw resistance of the eco-sustainable brick despite its high porosity and absorption. Furthermore, using cement brick with CBW particles is acknowledged as a more environmentally beneficial combination. The proposed models can speed up the process of mix design by using different sizes of brick waste to get the optimum eco-friendly cement brick properties.

A viable strategy for promoting sustainable development and a cleaner environment is the reuse of demolition-related ceramic waste and ceramic manufacturing byproducts in the production of concrete. The purpose of this study is to assess the possibilities for using ceramic waste in the production of concrete as a fine aggregate and cementitious material. The effectiveness of concrete mixtures incorporating 20–100% ceramic waste fine (CWF) as a replacement for natural fine aggregate and 10–30% ceramic waste powder (CWP) in place of cement was evaluated. Their influence was assessed with respect to workability, mechanical performance, durability, and elevated temperature resistance. The results were analyzed via energy dispersive x-ray (EDX) and scanning electron microscopy (SEM). The findings illustrated that the increase in the replacement levels of CWP and CWF decreases the concrete workability. The mechanical performance of concrete mixtures is enhanced under compression and flexural tests as the replacement ratios of CWF and CWP increase up to 50% and 10% as replacements of sand and cement, respectively. The increases in compressive and flexural strength were 5.33% and 8.14%, respectively, at age 28 days. The concrete water permeability significantly increases as the CWF replacement ratio increases, and the incorporation of CWP reduces this negative impact. After exposure to 200, 400, 600, and 800 °C, the residual compressive strengths of concrete mixtures incorporating CWF and CWP were up to 95.02%, 89.66%, 74.33%, and 51.34%, respectively, compared to control mixtures, which achieved 84.25%, 76.03%, 59.36%, and 35.84% of their initial strength. Microstructure analysis revealed that combining CWP and CWF significantly improves cement hydration when compared to the reference mixture. Thus, the use of CWF and CWP in the production of masonry mortar might be an economical alternative that would aid in raising the recycling rate of demolition and construction debris and supporting sustainable growth in the building sector.

The purpose of this investigation is to assess and optimize the impact of hybrid polypropylene fibers (coarse monofilament and staple fibers) on the mechanical characteristics and resistance to elevated temperature of high-performance concrete. Concrete mixtures were designed using central composite design under response surface methodology. Slump test, compressive strength, flexural strength, impact test, elevated temperature resistance and microstructure of concrete were the tests performed. The slump values were slightly decreased with the addition of polypropylene fibers. Concrete mixtures reinforced with hybrid polypropylene fibers have significantly improved in terms of compressive strength and flexural strength ranged from 1.96% to 12% and 14.28% to 41.9%, respectively, at age 56 days compared to control mixture without fibers. The hybridization of 5 kg monofilament and 0.75 kg staple fibers achieved the highest compressive strength (84.6 MPa), flexural strength (14.9 MPa), and the optimum impact resistance at age 56 days. The increase of coarse monofilament fibers significantly improved the spalling resistance performance. The residual compressive strength of mixture containing 5 kg monofilament and 0.75 kg staple fibers up to 63.8% of the initial strength after exposure to 800 C0. Strong relationships were obtained for predicting and optimizing compressive and flexural strength of concrete incorporating hybrid polypropylene fibers.

Sustainable eco-friendly ultra-high-performance concrete (UHPC) is a remarkable innovation in construction technology. This research aims to develop sustainable UHPC by incorporating various supplementary materials, including silica fume (SF), glass powder (G L P), fly ash (FA), limestone powder (LP), and granite powder (G r P), as partial replacements for cement and fine aggregate. To achieve this goal, a total of twenty-seven concrete mixtures were designed using response surface methodology (RSM) and tested in order to determine the optimal combination of these supplementary materials for enhancing the mechanical properties of UHPC. Mathematical models were constructed using analysis of variance (ANOVA) test. The results of the study suggest that it is indeed possible to produce sustainable UHPC with reduced CO 2 emissions and improved mechanical properties by utilizing the suggested supplementary materials. In particular, the compressive and flexural strengths of the concrete significantly improved when high proportions of LP, SF and G L P, and low proportions of FA and G r P were used. Among the various mixtures tested, the mixture containing 12.5% SF, 15% FA, and 10% G L P as partial replacements of cement, along with 12.5% G r P and 50% LP as partial replacements of fine aggregate, exhibited the highest compressive and flexural strength at all curing ages, the compressive strength was 133, 175.8, 180.2 MPa at age 7, 28 and 90 days, respectively, meanwhile the flexural strength was 38.5 MPa at age 28 days. The SEM results revealed that the higher proportion of LP, FA, and G L P contributed to an enhanced concrete microstructure, further validating the positive impact of these supplementary materials on UHPC's mechanical properties.

Industrial waste contributes to serious environmental issues. However, these issues can be solved by utilizing them as building materials. This paper investigated the effects of substituting the cement with a variety of industrial wastes and metakaolin (MK) on ultra-high-performance concrete (UHPC) properties. The industrial wastes used in this study include silica fume (SF), granulated blast-furnace slag (GGBS), and fly ash (FA). The prepared mixtures were created by varying the amounts of Portland cement, GGBS (30-50%), FA (20-30%), or MK (15-25%), while maintaining a constant amount of SF of 15%. The mechanical, durability, and micro-structural characteristics of the mixtures were investigated. This study also uses life cycle assessment to estimate the reductions in embodied energy consumption, life cycle cost, and carbon footprint associated with integrating metakaolin and industrial waste. The results indicated that the inclusion of 15%MK led to an increase in the compressive, flexural, and splitting tensile strengths. Also, the chloride permeability resistance was enhanced. The mechanical properties and chlorideion permeability resistance of the ternary mixtures with 50%GGBS and 25%MK were the lowest compared to other mixtures. These results were supported by SEM micrographs and EDX analysis for the UHPC structure, which demonstrate the high-density microstructure and extremely thin interfacial transition zone thickness. The inclusion of industrial waste and metakaolin can lower environmental impact of UHPC without compromising the mechanical performance. Also, the environmental assessment shows that the UHPC containing industrial waste has a lower impact on the environment, which means they could make cleaner products in the near future.

The aim of this study is to experimentally investigate the mechanical characteristics of concrete combining silica fume (SF) and magnetized water (MW). A total of nine concrete mixes were prepared and tested for workability, compressive strength, splitting tensile strength, and flexural strength. Ordinary tap water (TW) and MW that was prepared with five proposed different methods were utilized in the concrete mixes. The MW was prepared by passing TW through a permanent magnetic field (having intensities of 1.4 Tesla and/or 1.6 Tesla) for a different number of cycles, namely 100, 150, and 250 cycles. Water characteristics were analyzed after being magnetized using the proposed different methods and compared with the TW characteristics. Non-destructive concrete testing (ultrasonic pulse velocity, and Schmidt hammer) was also conducted to determine the effect of MW on the prediction of concrete compressive strength. Scanning electron microscopy (SEM) analysis and energy dispersive X-ray (EDX) analysis were carried out on the produced mixes. Regardless of the method utilized to prepare the MW, the results revealed a considerable improvement in concrete compressive strength, splitting tensile strength, and flexural strength by up to 80%, 98%, and 22%, respectively, when MW was prepared with 150 cycles. The best water magnetization method found in this study was the passing of water through magnetic fields of 1.6T then 1.4T intensities for 150 cycles. The ultrasonic pulse velocity test resulted in good prediction of the concrete compressive strength with overall error ranged between −12.6% and +5.8%. MW significantly improved the concrete microstructure and produced a denser structure in comparison to the control conventional concrete.

This investigation aims to predict and optimize self-consolidating the total powder content. Total powder content (P), proportion of and proportion of high-range water-reducing admixture (HRWRA) were the input parameters of the mixtures, and the desirable responses were slump flow, 7- and 56-day compressive strength, and flexural strength. A total of 90 concrete mixtures were designed using the central composite design (CCD) concept in Minitab 18 statistical software under response surface methodology (RSM) to simulate and optimize the variables and responses of models. Results showed that high relation can be developed between the responses and the constituent materials in predicting characteristics of SCC, removing the drudgery of repetitive laboratory testing and enabling rapid decision-making for building applications. The slump flow increased with the increase in total powder content, FA content, w/p, and HRWRA dosage and decrease in SF content, while LP has insignificant effect on slump flow results. The increase in partial replacement of cement by FA decreased the compressive strength of mixtures at early ages. The higher values of compressive strength were observed when SF incorporated in higher levels, and flexural strength also enhanced with the increase in SF content.

Compared to conventional concrete self-consolidating concrete (SCC) has a higher cost due to the large content of cement, use of mineral fillers, and use of various chemical admixtures, resulting in relatively high material cost. The proper selection of material and mixture proportioning can enable reduction in cement and admixture contents, leading to savings in cost. This study investigates the potential of optimizing fresh properties and 28-day compressive strength of SCC incorporating fly ash (FA), silica fume (SF), and limestone powder (LP) as part of cement by mass in total powder content. The input parameters of mixtures were total powder content (P), percentage of FA, percentage of SF, percentage of LP, water to powder ratio (W/P), and percentage of superplasticizer (SP) whereas slump flow, L-box (H2/H1), segregation index, and 28-day compressive strength were the desirable responses. A total of ninety concrete mixes were designed using central composite design (CCD) concept and checked experimentally using artificial neural network (ANN) in MATLAB. Analysis of variance test (ANOVA) used to establish the mathematical models. Results indicated that fresh characteristics of SCC enhance with the increase in FA percentage while the 28-day strength decreases. Slump flow diameter and L-box (H-2/H-1) ratio decrease with the increase in SF percentage. Nevertheless, the increase in silica fume improves the resistance of SCC to segregation and increases the 28-day strength. Using limestone powder as a replacement of cement content resulting in negative impact on L-box (H2/H1) ratio and 28-day compressive strength while the resistance to segregation enhances. High relations between the responses and the constituent materials of SCC can be developed using response surface methodology (RSM) and the optimum values of variables can be estimated to achieve the desirable properties of responses. (C) 2020 Elsevier Ltd. All rights reserved.