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Reinforced concrete has a weakness for corrosion which can cause the concrete to crack and the concrete structure to fail. To overcome this problem, a self-healing concrete method is needed that can close cracks and inhibit the rate of natural corrosion. Bacillus subtilis as a self-healing agent in concrete has been proven to be able to increase the compressive strength and flexural strength of concrete. The method used in this research is to add bacterial hydrogel encapsulation to concrete with a variation of 0%; 0.1%; 0.6%; and 1.5% by weight of sand. The test object is a reinforced concrete beams and cylindrical concrete with compressive design strength of 30 MPa. The concrete specimens will go through a series of tests, such as corrosion acceleration tests using DC power supply, self-healing tests by visual observation, flexural strength, ductility, stiffness, and compressive strength tests using Universal Testing Machine (UTM). From the test results, it was found that the addition of 0.1% bacterial encapsulation variation was the optimum value for increasing the mechanical properties of self-healing concrete and reduce the corrosion rate on self-healing concrete

Innovative building materials are the primary focus for researchers seeking to reduce energy consumption and advance global sustainability initiatives. This target could accomplished by addressing environmental issues and confronting the adverse impact of climate change. In this regard, this paper used a combined experimental and simulation approach to evaluate the effectiveness of lightweight geopolymer concrete (LWGC) incorporating industrial waste of aluminum powder (AP) and ferrosilicon waste powder (FWP) for reducing the energy consumption in the building envelop. Seven concrete mixes for LWGC were prepared using an air operator. Three mixtures contain 0.1 %, 0.2 %, and 0.3 % AP (FA), and three mixtures contain 0.1 %, 0.2 %, and 0.3 % FWP by weight of fly ash. The workability, unit volume weight, compressive strength, thermal conductivity, and microstructure analysis of the LWGC were examined. In addition, energy simulations were performed to evaluate their ability to reduce energy use in residential buildings. The inclusion of AP and FWP in LWGC resulted in a significant decrease in the density of the material, which amounts to 55 % for AP0.3 and 35 % for FWP0.3. The diameter of the LWGC pore structure increased as the Ca/Si ratio was reduced. The AP and FWP materials reduced energy consumption for building envelope elements such as external walls and roof insulation by 14.5 %, resulting in a 9.2 % overall reduction compared to the traditional concrete mix as a control sample.

This investigation aims to study the effect of the harsh environment on cement mortar containing pumice powder (natural pozzolana) as a partial substitute for ordinary Portland cement (OPC). The harsh environmental conditions applied in this study consisted of seawater supplemented with 5% of sodium sulfate (Na2SO4). Mortar mixtures were produced by replacing 0%, 5%, 10%, and 20% of the OPC mass with natural pozzolana (NP). Mortar samples were treated under two conditions. First, the mortar samples were immersed in tap water. Second, mortar samples are immersed in harsh environmental conditions. In the harsh environment, mortar samples were subjected to 90 cycles of dry-wet, 48-hour drying, and 48-hour wetting over a period of 360 days. Compressive strength, flexural strength, strength loss, change in length, water absorption, and initial surface absorption tests were performed on specimens aged 7, 28, 90, 180, and 360 days. Besides thermogravimetric and microstructure analysis of cement samples that were conducted at a test age of 180 days. The inclusion of NP as a partial replacement of OPC at a rate of 10% improved the results of compressive and flexural strength and achieved the lowest rates of porosity and water absorption of the mortar samples. The inclusion of NP as a partial replacement for OPC reduced the damage caused by the harsh environment.

One of the most present types of concrete in buildings is ultra-high-performance concrete. In contrast, large quantities of cement are consumed to achieve the required strength. To minimize the quantity of cement utilized in manufacturing ultra-high-performance concrete, this research aims to look at the usage of a unique agricultural waste as an alternative to cement. This study focuses on using agricultural waste as a partial cement alternative to reduce the amount of cement used in the production of ultra-high-performance concrete. This study employed basil plant ash as a partial substitution for ordinary Portland cement at 5 %, 10 %, 15 %, 20 %, and 25 % by mass. basil plant ash was heat-treated at temperatures of 300 °C, 500 °C, 700 °C, 900 °C. The compressive strength, splitting tensile strength, and sorptivity coefficient of ultra-high-performance concrete were investigated using 21 different mixes. In addition, microstructure characteristics as assessed using X-ray diffraction, thermal gravimetric analysis, and scanning electron microscope. The results showed that treating basil plant ash at 700 °C contributed to achieving the best mechanical properties when it was utilized as a partial substitution for 20 % of the weight of ordinary Portland cement. The compressive strength and splitting tensile strength were enhanced by 15.07 % and 20.39 %, respectively, compared with the control mix at 28 days. The thermo-gravimetric analysis, X-ray diffraction, and scanning electron microscope analyses are consistent with the obtained mechanical and durability characteristics. The outcomes of this investigation help shed light on the use of basil plant ash as a partial substitution at a level of 20 % of the weight of cement to produce ultra-high-performance concrete with high performance and lower cost.

This research aims to study the effect of adding nanosilica (NS) on the properties of sustainable high-strength concrete (SHSC). The SHSC was produced using recycled aggregates from concrete debris as a 100% alternative to coarse aggregate, and industrial waste was used as supplementary cementitious materials at 50% and 75% of Ordinary Portland cement (OPC) weight. A total of 25 mixes, including control mix (The first mix was made as the reference by using only cement without replacement materals), binary mixes (OPC and fly ash (FA)), ternary mixes (OPC, FA and ground-granulated blast-furnace slag (GGBS)) and quaternary mixes (OPC, FA, GBFS and silica fume (SF)) were developed. The dosage of NS was 0%, 1%, 3% and 5% by binder ratio. The fresh properties of SHSC were evaluated by slump test, and the mechanical properties were assessed by testing the compressive strength, splitting tensile strength, flexural strength and modulus of elasticity. The transport properties were evaluated by water permeability, water sorptivity and chloride permeability tests. Results showed that compared with the reference mixture, the SHSC containing 75% of the quaternary blends with 3% NS achieved enhanced mechanical properties at 28 and 91 days, indicating that this mixture can achieve the highest sustainability performance. The SHSC mixture containing 3% NS and 50% quaternary mixtures achieved the highest performance of 80.7, 6.46 and 10.09 MPa for compressive strength, split tensile strength and flexural strength, respectively, at 28 days. This SHSC mixture also achieved water permeability; chloride permeability was 2.54 × 10−11 (cm/sec) and 1370 coulombs at 28 days.

This research investigates the feasibility of using dry crushed pomegranate peel waste as thermal insulator to produce light clay bricks. Pomegranate peel waste (PW) is used with different substitution levels of 0%, 5%, 7.5%, 10% and 15% of clay weight. The clay bricks were heated at temperatures of 700, 800, and 900 °C, that resulted in the formation of internal pores due to the combustion of PW. The bulk density, water absorption, porosity, shrinkage, and compressive strength are examined to evaluate the effect of using PW on the physical and mechanical properties of thermal insulation bricks. Also, the investigation of the effect of photocatalytic activity of bricks under sunlight irradiation is carried out. The use of PW increased the thermal conductivity up to 21% at 900 °C, water absorption from 22.6% in cold water to 29.1% in boiling water, density from 2.5% at 800 °C to 7.6% at 900 °C, and shrinkage from 4.3% in linear drying shrinkage to 5.4% in linear firing shrinkage. The heated brick samples at 700 °C showed greater photodegradation efficiency than firing clay at 800 °C and 900 °C. Moreover, the compressive strength decreased with the increase in replacement rate, reaching up to 74% for 15 wt% PW. This study confirms that lightweight heated bricks with low thermal conductivity and a reasonable compressive strength can be made using PW as a pore-forming agent.

Agricultural countries suffer from growth problems of agricultural waste ash (AWA). This research paper studies the use of AWA as a partial substitute for cement to produce ultra-high-strength concrete (UHSC). This paper also investigates the effect of using sugarcane bagasse ash (SBA) and corn stalk ash (CSA) on the properties of UHSC. Residues from the combustion process of agricultural wastes are utilized as a pozzolanic material inserted as a partial substitute for cement for UHSC production. The replacement rates of cement by the SBA were 10%, 20%, and 30% of the mass, whilst those of cement by the CSA were 2%, 4%, 6%, and 8% of the mass. The effects of SBA and CSA on workability, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity on UHSC properties were investigated. In addition, the effects of SBA and CSA on resistance to chloride ion penetration and water sorptivity and permeability in UHSC were investigated. The investigations showed impressive results. That is, producing UHSC with respective compressive and flexural strengths of more than 205 and 27 MPa is possible when 24% of cement mass replacement by AWA (SBA 20% + CSA 4%) is conducted at the test age of 28 days. The lowest permeability is achieved with 38% of cement mass replacement by AWA (SBA 30% + CSA 8%) of 140 coulombs and 0.95 (cm/sec) for chloride and water permeability, respectively.

Industrial wastes have been widely used worldwide in the construction industry as a pozzolana aiming to reduce Portland cement utilization and to produce economical, energy-efficient, and environment-friendly concrete. Fly ash is a well-recognized and extensively used pozzolana in concrete, whereas pumice has been scarcely used for this purpose. This study intends to experimentally investigate the beneficial utilization of textile industry waste-derived pumice powder (PP) and its comparison with Fly Ash (FA) in concrete. A total of ten mixes of concrete were prepared with PP, FA, and their ternary mixes (PF) by replacing cement with 15 %, 25 %, and 35 %, respectively. The results show that PP possesses higher pozzolanic potential attributed to the presence of higher content of amorphous silica (SiO2) as detected in the X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) test and justified by the Strength Activity Index (SAI). Moreover, the addition of both pozzolana enhances rheological properties along with the workability of fresh concrete. In the case of Mechanical properties, the inclusion of 25 % PP shows better performance among all mixes, whereas FA mixes gain strength in later ages. Furthermore, the hydration products assessed by thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR) analysis justified the formation of secondary hydration products and higher pozzolanic potential of PP.

The aim of this research is to investigate the influence of cement mass replacement with volcanic pumice dust (VPD) at levels of 10 %, 20 %, and 30 % on the performance of high-strength concrete (HSC) under submerging (SuC) and internal curing (InC) methods up to 180 days of age in hot weather climates. Two curing techniques were tested in this study in hot weather climates: (i) the specimens were submerged in a water container inside lab conditions and (ii) the specimens were left outdoors uncured until the day of the test. The fresh properties (slump test) and hardened properties (i.e., compressive, splitting tensile, and flexural strength), as well as water absorption, sorptivity, and microstructure (thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy), were evaluated experimentally. At age 180 days, application of the InC technique preserved compressive strength in the range of 74.5–85.8 % versus SuC for all replacement levels; meanwhile, this technique preserved splitting tensile and flexural strengths in the range of 86.8–93.1 % and 77.0–90.1 %, respectively. Utilizing VPD improved the permeability qualities by decreasing the water absorption ratio compared with the control specimen at all test ages. Despite the decrease in the hardened concrete characteristics, the application of InC achieves acceptable results compared with the amount of water that will be saved, especially in hot weather.

This study explored the potential of producing geopolymer bricks from industrial waste including ferrosilicon and aluminum slag. The bricks' physico-mechanical properties show that they conform to many codes and standards. Also, the thermal conductivity of 0.28 W/mK is achieved, which is significantly lower than that of conventional bricks. social residential buildings in New Aswan City, Egypt, is employed as a case study for examining the fabricated bricks' implementation. Using the Design Builder software, it was found that the proposed fabricated brick samples showed energy savings of 5.70–14.90% and a decrease in carbon dioxide emissions of 0.47–7.67% compared to conventional wall brick. The temperature profile reveals that the fabricated brick samples have achieved the desired level of human comfort. Finally, the financial viability of each brick type was analyzed using the simple payback time (SPP). A return on investment of 8.76–15.79 years was determined for the produced brick samples. Therefore, geopolymer bricks are widely recognized as a significant improvement in environmental sustainability.

The usage of cement is responsible for approximately 10% of anthropogenic CO2 emissions. Therefore, the use of supplemental cementitious materials in concrete was made possible by the demand for more affordable and environmentally friendly ingredients. Different cement-replacing alternatives are now often used in the construction sector. This study aims to investigate the possibility of using wastepaper sludge ash (WSA) and pulverized fuel ash (PFA) as partial substitutes for cement with different levels for the production of self-compacting concrete (SCC). Fourteen SCC mixtures with 0.4 and 0.45 water/binder (W/B) ratios, two controlled mixtures (i.e., without WSA and PFA), and two sets of six combinations with varying WSA and PFA replacement levels (5–30%) of cement were prepared and investigated. The characteristics of fresh concrete (slump flow and L-Box) and hardened concrete (compressive strength, tensile strength splitting, and modulus of elasticity) were examined. Results show that the WSA can substitute for up to 5% (optimal percentage replacement) of the weight of regular ordinary Portland cement (OPC) with an improvement in SCC’s fresh and hardened properties. The fresh and hardened properties of SCC containing WSA and PFA decrease as the replacement levels increase above 5%. Using WSA and PFA as construction materials is cost-effective because they may be used in place of OPC to produce good quality SCC.

This study primarily aims at investigating the impact of incorporating volcanic pumice powder (VPP), with different steel fibers on self-compacting concrete (SCC) beams’ performance with a circular opening of a diameter of 20 mm at the centroid. To this end, twenty-one SCCs opened beams (100 mm × 100 mm × 500 mm); together with/without steel fiber, were cast and examined by employing the test of center-point bending. For this study, five different types of fiber and various aspect ratios, involving the hook-end fiber type of (60–30 mm), the straight fiber type of (21–13 mm), as well as the flat-end fiber type of (six varying concrete mixtures made by adding 1% of a volume fraction), were examined. At a replacement rate of 30% of the cement mass, VPP has been incorporated into the mixture. The experimental test results confirmed the performance improvement in deflection, a failure load, and a failure mode due to the existence of steel fibers in the examined concrete matrix. The presence of steel fibers has significantly increased the ultimate loads with a range of the gain ratio of 11–49% compared with solid beams (i.e., SCC beams). Accordingly, the fibers were able to offset the drawbacks, which were triggered by the opening. Moreover, this study demonstrated the possibility of benefiting from industrial wastes, such as VPP to reduce the use of cement and manufacture of SCC.

The effect of partial replacement of coarse aggregate by plastic waste on the performance of concrete under impact three-point bending loading was investigated experimentally and numerically. Specimens were prepared for 5%, 10% and 20 % replacements by volume of coarse aggregate. For each case, three beams of 100 mm wide, 50 mm deep and 400 mm long were loaded to failure in a drop-weight impact machine by subjecting it to 30 N weight from 400 mm height, while another three beams of the same size were tested under static load. The load-displacement of beams of concrete with plastic waste subjected to static and impact loads were studied. The dynamic beam behaviour was also analysed numerically using the finite-element method (FEM) based LUSAS software. In general, the experimental results reveal that the impact tup, inertial load and bending load increase with the increase in the percentage of coarse aggregate replacement by plastic waste, while the static peak bending load always decreases. The concrete with plastic waste is stronger and more energy-absorbing under impact loading, than under static loading. The predicted load against displacement behaviours of both ordinary concrete and concrete with plastic waste, are well matched with the experimental results.

Effect of steam curing regimes on high-performance green concrete (HPGC) has been studied. The concrete was steam cured under three different steam curing regimes with temperatures of 50 °C, 65 °C, and 80 °C and durations of 6, 11, and 16 h. In addition, the replacement level of palm oil fuel ash (U-POFA), which was an experimental variable, was 0%, 20%, 40%, and 60% by weight of cement. The compressive strength (CS), initial surface absorption, porosity, water absorption, gas permeability, and water permeability were tested at 3, 7, 28, 90, 180, and 360 days. The results of the study showed that the utilization of U-POFA in HGPC led to a reduction at the early age CS of the HPGC up to 3 days. However, concrete mixes made with U-POFA showed higher CS at 28–360 days. U-POFA incorporation improved the transport properties of the concrete, with U-POFA60 mix exhibiting the most significant improvement. While application of higher curing temperature tends to impair the properties of the HPGC, longer steam curing period appears to provide a positive effect than shorter duration. The use of U-POFA lessens the negative impact of steam curing on the long-term transport properties of the HPGC. The use of U-POFA at 60% of the weight of the cement achieved CS of 115.8 and 116.9 MPa at 360 days under normal and steam curing, respectively. At the same time, the water absorption was 3.13% and 2.29% under normal and steam curing, respectively.

The urgent need to find green alternatives to cement concrete in order to reduce the consumption of fossil fuels and non-renewable resources that are used to produce cement. This research aims to study the possibility of using volcanic pumice dust (VPD) waste with cement kiln dust (CKD) or Ordinary Portland cement (OPC) to produce alkaline activated green concrete (HAC). VPD was used to improve the mechanical performance, strength, and engineering properties of HAC. CKD and OPC were used as a partial replacement for VPD in different proportions of 0, 5%, 10%, 20%, and 30% by weight. Na2SiO3 and NaOH were used as alkaline activator solutions to realize the alkaline reaction process in geopolymer paste. Workability, compressive strength, and engineering properties, such as bulk density, porosity, and water absorption, were studied. Results of this research indicated that increasing the replacement rates of CKD or OPC decreased slump flow but increased the strength of HAC and enhanced the values of its engineering properties. Geopolymer concrete with OPC and CKD as partial replacement of 30% by weight of VPD achieved an increase of 23% and 8%, respectively, in compressive strength at a test age of 90 days. Meanwhile, 20% VPD replacement by CKD achieved 11% higher compressive strength for the VPD–CKD samples compared with the control mixture. In addition, water absorption rate decreased by 25% and 20%, respectively, compared with the control samples.

The mining sector generates a considerable amount of waste stone and tailings, which constitute a ‎‎substantial hazard to the ecology. The most prevalent method of disposing of these industrial ‎‎wastes is by dumping, which adds to soil deterioration and water contamination and also takes up ‎‎valuable land. Fortunately, it can be recycled in a variety of ways, including the promising ‎‎geopolymerisation technique, which converts waste into value. This article discusses recent ‎‎advances in the production of mine tailings-based geopolymers composites (MT-GPC) from waste and ‎‎industrial by-products as a potentially sustainable construction material. Besides, focusing on the ‎‎following ‎‎aspects: economic and production perspective; environmental consequences and waste ‎‎disposal; physical and chemical properties; mechanical properties; durability properties; ‎‎microstructure properties‎; thermal properties; and potential applications of MT-GPC.‎

Recent innovations in the field of concrete have contributed to the development of lightweight geopolymer concrete (LGC), which can be produced by adding an air agent. This study investigates the possibility of producing an air agent from the powder slag of ferrosilicon (FSS), an industrial waste. A class F fly ash (FA) was used for GC synthesis, and aluminium powder (AP) and FSS were added as air agents for LGC synthesis. The performance of FSS and AP as an air agents was compared by studying the properties of LGC produced under the same conditions. Air agents with 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 1.0% mass of FA were adopted to produce LGC. Thirteen mixtures were prepared to evaluate unit weight, the fresh and mechanical properties and the microstructure of LGC with PA and FSS air agents. Influence of high temperature of 200–800 °C for 2hrs on LGC was also investigated. The results show the possibility of using FSS waste powder as an air agent in LGC production. In terms of workability and unit weight, FSS was better compared to AP at the same percentage addition. The slump flow and unit weight, were 548 mm, 1830 kg/m3, and 569 mm and 1740 kg/m3, while compressive strength was 24.7 and 21.8 MPa for LGC containing 1% AP and 1% FSS, respectively.

Research interest in producing sustainable ultra high performance concrete (UHPC) has been increasing recently. This paper focuses on the use of recycled coarse aggregate (RCA) as a replacement for 50% of the total natural coarse aggregate (NCA). Two types of replacements were used, namely, carbon nanofiber (CNF) with 0.25%, 0.5%, 0.75%, and 1% by weight of binder and steel fibers (SFs) with 0.5%, 1.0%, 1.5% and 2% of by weight of the binder. In addition to this, hybrid fibers, i.e. a combination of CNF with SFs were also used for few mixes. Twenty-six mixtures were prepared to evaluate the engineering properties of UHPCs containing RCA and NCA with CNF and SFs. The mechanical properties were evaluated through tests of the compressive, split tensile, and flexural strengths and the modulus of elasticity. The mass and compressive strength losses were examined to evaluate the effect of UHPC exposure to elevated temperatures (200 °C, 400 °C, 600 °C, and 800 °C). The incorporation of NCF, SFs, and RCA negatively affected the workability, and the diameter of the slump flow was reduced to 230 mm for RCF0. 25-SF2.0 mixture. The addition of fiber contributed to the improvement of the concrete properties. The compressive strengths were 151.3 and 146.9 MPa for the NF0 and RF0 mixtures, respectively. In fiber addition to UHPC, the best improvement was achieved at 164.9, 158.6, 158.8, 153.5, 167.9 and 180.9 MPa for the NCF0.5, RCF0.5, NSF2.0, RSF2.0, NCF0.25-SF2.0 and RCF0. 25-SF2.0 mixtures.

Alkali-activated materials (AAMs) are promising materials that can be used as alternatives for conventional Portland cement (PC) materials. In this paper, the fresh properties, and mechanical properties of AAMs made with glass powder (GP) as the precursor were explored and discussed. The discussions presented in this paper showed that the incorporation of GP as the precursor in AAMs resulted in an improvement in the workability and extension of the set times. However, the use of GP especially at early ages could result in a detrimental impact on the mechanical performance of AAMs due to the lower reactivity of GP compared to other precursors. Nonetheless, AAMs with acceptable mechanical performance for non-structural and structural applications can still be produced with the use of GP as the precursor.

Brazil is a country of continental dimensions and characteristics with enormous biodiversity of fauna and flora which confers a prominent role in the sector of extraction of agricultural products. However, one of the current challenges is the increasing amounts of agricultural solid wastes generated by different local production processes which end up resulting in enormous environmental liabilities. One way to effectively manage these agro-industrial wastes is by their application in the development of alternative cementitious materials such as mortars and concretes. Thus, the objective of this paper is to discuss the recent advances, challenges and future perspective of the application of some solid agro-industrial wastes generated specifically in Brazil and some other parts of the world in cementitious materials. The application of wastes from pineapple, sugar cane, açai, coconut and rice were explored and discussed. The discussion presented in this paper is anticipated to strongly contribute to the advancement of public policies that enable the real application of these wastes in the development of eco-friendly cementitious materials for civil construction.

Steam curing at atmospheric pressure is a method used to raise concrete strength at early ages. The steam curing method is based on the application of hot water vapor at a temperature between 40 °C and 100 °C for a limited period. The highest temperatures and the longest curing period are determined based on the characteristics of the target concrete, the cost, and the production cycle. This study presents the effect of steam curing regime application on concrete properties. Steam curing has a negative effect on the microstructure of concrete, and this effect increases with higher temperatures. The curing period and the precuring period in addition to the cooling period influence the properties and the strength of concrete. This study summarizes the previous literature related to the effect of steam curing regime application on the properties of concrete. Previous studies confirm that concrete exposed to steam curing regime at low temperatures ranging between 45 °C and 80 °C and a longer period within a 24-hour cycle achieve better concrete properties. In addition, raising the steam curing temperatures above 80 °C has a negative effect on concrete microstructure and other concrete properties in general. This study also concludes that adding pozzolanic or complementary cement materials contributes to reducing the damage resulting from the application of steam curing regime on concrete at later ages. Such verification is required to clarify the behavior of concrete under the influence of steam curing systems, understand their effect on the properties of concrete, and look for ways to reduce the damage from degrees of application of steam curing regime.

This research aimed to experimentally examine the workability and mechanical properties of self-compacting concrete (SCC) with silica fume (SF) and different types of fibers. Five types of fibers, namely, hook-end steel (H), mild steel (M), carved-steel (S), basalt rock (R), and polypropylene (P) fibers, were used to produce fiber-reinforced SCC (SCRFCx). Each fiber type was added to the concrete at a rate of 0.25% of the concrete volume, and a silica fume replacement rate of 30% of the cement mass was applied. The workability of fresh concrete samples was assessed using slump flow, slump flow T50, L-box, V-funnel, V-funnel T5, bleeding, and segregation tests. In addition, the overall strength of hardened concrete was investigated by using compressive, indirect tensile, and flexural strength tests. Results showed that fiber addition generally reduces the fresh concrete. The slump flow diameter was 670 mm of SCC; moreover, slump flows decreased to 630, 640, 640, 610, and 650 mm when H, M, S, P, and R fibers were respectively added to the concrete. The respective compressive strengths were of 34.5, 33.9, 32.1, 36.9, 35.8, and 33.3 MPa when add the fibers of type H, M, S, P, and R, at test age 28 d, respectively.

Self-compacting concrete (SCC) requires specific properties, such as fillability, flowability, and passability. It also needs to resist bleeding and segregation, which may be caused by increased water or superplasticizer (SP) content. In addition, long periods of mixing deteriorate the properties of fresh SCC and causes difficulty in filling structure sections. This study investigates the effect of different mixing periods (e.g., 15, 30, 60, and 90 min from the addition of water to the mixture) and increased SP doses (e.g., 1.5%, 2%, 2.5%, and 3% of cement mass) on the properties of SCC mixtures. The properties of fresh concrete were assessed by seven tests, namely, slump flow, V-funnel, slump flow T50, V-funnel T5, L-box, bleeding, and segregation. Hardened concrete was assessed on the basis of compressive, indirect, and flexural strengths. Results showed that compared with the slump flow under 15 min mixing time, the 30, 60, and 90 min increase in mixing time reduced slump flow by 6%, 19%, and 27%, respectively. Findings also showed that results of SCC segregation and bleeding decreased when increased mixing time. The results also appeared that compressive strength of SCC slightly decreased compared with that under 15 min mixing time. The increase in dosage of superplasticizer has mitigated the negative effect for long mixing periods on the properties of concrete.

In this paper, the partial replacement of volcanic pumice powder (VPP) was investigated for use as a supplementary cementitious material. High-strength concrete (HSC) was prepared using two sets of VPP (10% and 20%) incorporated with three sets of polypropylene fiber (PF) (0.20%, 0.35%, and 0.50%) to produce different concrete mixtures. Several tests, including slump, compressive strength, indirect tensile strength, flexural strength, water absorption, initial surface absorption, and sorptivity, were conducted to evaluate HSC performance. Results showed the prepared specimens with 10% cement replacement with VPP and 0.20% PF content indicated a slight increase in compressive strength compared with the control concrete at later ages. Indirect tensile and flexural strengths were optimized at 10% VPP replacement with 0.50% PF content. Furthermore, adding PFs to mixes increased indirect tensile and flexural strength but decreased slump. The sorptivity test indicated low water soaking due to VPP content in the mixes compared with the control mix (HSC); it declined as the replacement of VPP increased. The different standard tests on mixes depicted favorable results and good prospects for the inclusion of VPP in HSC structures. Keywords: Compressive strength, Cementitious material, Environmental pollution, High-strength concrete, Polypropylene fiber, Workability, Volcanic pumice

The environmental aspects of sustainable development in the construction industry consist of the utilization of secondary raw materials and materials which can be recycled in the design and construction of new structures. The preliminary and inevitable interest in the use of full or partial replacements of by-products as complementary pozzolanic materials was mostly induced by the enforcement of the reduction/elimination of the greenhouse gas emission from the production of Portland cement. With the significant evolution of geopolymer concrete as an alternative for Portland cement in the past decade, it is necessary to explore possible construction applications in which geopolymer concrete can be utilized. Hence, this review paper was carried out to explore various elements such as the precursors used in geopolymers concrete and their corresponding applications. The environmental impacts of various geopolymer concrete are also discussed. This paper also presents an overview of the real applications of geopolymer concrete for the construction of various infrastructures. Recommendations and prospects for geopolymer concrete are also provided.

The present study introduces the preparation of thermal insulation geopolymer bricks using ferrosilicon slag and alumina waste. Compressive strength, bulk density, cold and boiling water absorption, apparent porosity, thermal conductivity, and Fourier-transform infrared spectroscopy were used to characterized the geopolymer bricks. Ferrosilicon slag suffers from low alumina content. Thus, alumina is added to compensate for this deficiency. Pristine ferrosilicon slag and the SiO2/Al2O3 (Si/Al, ratio=2) sample were prepared at different NaOH concentrations (i.e., 6, 8, 10, and 12 M; Na2SiO3/NaOH ratio=2.5), different curing times (i.e., 3, 7, 14, and 28 days), and room temperature. The 8 M NaOH concentration achieved the best compressive strength. Accordingly, different Si/Al ratios were prepared and tested at 8 M NaOH, room temperature, and different curing times (i.e., 3, 7, 14, and 28 days). Results indicate that increasing the alumina content enhances the geopolymer properties but reduces the compressive strength of the prepared geopolymer. The sample with Si/Al ratio= 1 exhibited a higher compressive strength (10.9 MPa) than the other Si/Al ratios (i.e., 4, 3, 2, and 0.5) and the pristine ferrosilicon slag after 28 days of curing and at 8 M NaOH. The obtained value is consistent with the ASTM C62 and Egyptian standards. Furthermore, the addition of alumina waste decreased the thermal conductivity of the prepared geopolymer bricks.

This study aims to examine the effect of high temperatures on lightweight geopolymer concrete (LWGC) and lightweight ordinary concrete (LWOC) made of natural pumice and lightweight expanded clay aggregate (LECA) with the addition of trapped air. To this end, a geopolymer concrete matrix has been synthesized by the alkali-activation of fly ash (FA) and granulated blast furnace slag (GBFS). The geopolymer concrete samples were cured for 24 h at a temperature of 80 °C. To study the properties of fresh concrete, slump and slump flow tests and unit weight were applied. The mechanical properties were also measured by the compressive strength, splitting tensile, flexural strength, and elastic modulus tests. High temperatures of 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, and 800 °C were applied on the geopolymer concrete samples to obtain the residual compressive strength. In general, pumice and LECA can be used as an alternative to the dolomite aggregate to produce LWGC and LWOC. The mixture F-50D50P-A achieved the lowest of unit weight of 1660 kg/m, a slump flow of 555 mm, and compressive strength of 32.9 MPa at 91-days. Lightweight geopolymer concrete containing 50 % fly ash and 50 % GBSF achieved the best compressive strength test results. The results showed a similarity in the behaviour of LWGC with LWOC under the influence of all the variables applied in this study.

The properties of high-strength concrete (HSC) are significantly influenced by environmental conditions and the duration of the curing method. This paper presents an experimental study that investigated the influence of three types of curing methods during hot weather on the properties of hardened HSC reinforced with 0.0% or 0.22% (by volume fraction) polypropylene fibers (PFs). HSC samples were cured via water immersion under indoor laboratory conditions; wet-coverage with a wet gunny under outdoor conditions; and spraying with water twice day for one week under outdoor conditions. The concrete mixture was designed to achieve compressive strength beyond 60 MPa after 28 days of curing via water immersion. Various tests were conducted to determine HSC properties, including slump, compressive, indirect tensile and flexural strengths. Cubes, cylinders, and prisms were cast with each concrete mixture to measure strength at 7, 14, 28, and 90 days of curing. Compressive strength under all curing conditions with and without PF reinforcement exceeded 60 MPa at 28 days. PF-reinforced concrete cured via water immersion exhibited the best concrete strength. Keywords: Compressive strength, Curing methods, High strength concrete, Hot weather, Polypropylene fibers

Sustainable design methods aim to obtain architectural solutions that assure the coexistence and welfare of human beings, inorganic structures, and living things that constitute ecosystems. The novel coronavirus emergence, inadequate vaccines against the present severe acute respiratory syndrome-coronavirus-(SARS-CoV-2), and increases in microbial resistance have made it essential to review the preventative approaches used during pre-antibiotic periods. Apart from low carbon emissions and energy, sustainable architecture for facilities, building designs, and digital modeling should incorporate design approaches to confront the impacts of communicable infections. This review aims to determine how architectural design can protect people and employees from harm; it models viewpoints to highlight the architects’ roles in combating coronavirus disease 2019 (COVID-19) and designing guidelines as a biomedical system for policymakers. The goals include exploring the hospital architecture evolution and the connection between architectural space and communicable infections and recommending design and digital modeling strategies to improve infection prevention and controls. Based on a wide-ranging literature review, it was found that design methods have often played important roles in the prevention and control of infectious diseases and could be a solution for combating the wide spread of the novel coronavirus or coronavirus variants or delta.

Currently, a number of disadvantages hampers the use of recycled concrete aggregates (RCA). The current review proves that concretes made with complete replacement of natural aggregate with RCA allow the production of high-quality concrete. One of the possibilities for improving concrete properties with RCA is the use of extended curing and pozzolanic materials with varying cement ratios. The potential use of RCA concretes is in the production of high-value materials that increase environmental and financial benefits. RCA have strong potential in the development of a new generation of concrete and stimulate economic activity in many countries in addition to optimizing natural resources. Economic benefits include minimal travel costs; cheaper sources of concrete than newly mined aggregates; reduction of the landfill area required for the placement of concrete waste; the use of RCA minimizes the need for gravel extraction, etc. The proposed strategy could be to sequentially separate demolition waste such as roof finishes, waterproof materials, interior and exterior materials, etc. Closing life cycles is the main approach used for efficient structures for the recycling and reuse of construction and demolition waste in the production and recovery of materials, especially when recycling and reusing materials. In the life cycle, the recycling of recovered materials allows them to be used for new construction purposes, avoiding the use of natural concrete aggregates. Government, design institutes, construction departments and project managers should be involved in the creation and use of RCA. In demolition and construction, the main players are the project owners. Their obligations, expectations and responsibilities must be properly aligned. For the past 20 years, recycled concrete aggregate from demolition and construction waste has been considered as an alternative to pure concrete in structural concrete to minimize the environmental impact of construction waste and demolition waste and the conversion of natural aggregate resources. It is now recognized that the use of RCA for the generations of concrete is a promising and very attractive technology for reducing the environmental impact of the construction sector and conserving natural resources. In the market, the selling price is not an obstacle for market applications of RCA, as there are scenarios in which their cost is lower than the cost of products made from conventional building materials. This is more of an acceptance factor in the market for recycled concrete aggregates. In this sector, the lack of identification, accreditation and uniform quality certification systems and their narrow application cause some marketing problems. With proper RCA preparation, concrete with standard physical and mechanical properties and performance characteristics can be obtained.

The global sustainable construction aimed to minimize the ecological impacts of constructed facilities’ lifetime. In construction, concretes are the major materials utilized in South East Asia. Thus, it makes environmental and economic sense to utilize recycled materials in the production of new concretes for diverse uses. This review indicated that the practical implementations of the recycled aggregate concretes (RAC) in the area is greatly lacking, even though there are reasonable studies on RAC, particularly because of lack awareness and economic viability of such uses at the present period. This research aims to establish an interdisciplinary consortium with researchers, policy makers, practitioners, and social scientists in Southeast Asia to investigate the development of sustainable, durable, cost-effective, green concrete by utilizing recycled aggregates. Concentrating on waste resource recovery, this research presents an integrated modeling method. The approaches track and forecast a variety of values across technical, economic, social, and environmental areas linking these to the material flow and therefore integrating and building upon one-dimensional models like life cycle assessments (LCAs) and material flow analyses (MFAs). Additionally, the analysis of this study supported the recycling of cement for general use in construction, emphasizing the feasibility, reliability, and longevity of a project at the same time. However, the analysis also demonstrated that although there is fair progress on recycled concrete, there is still a severe lack of appropriate development in particular because of the lack of economic sustainability and knowledge of such applications at present. Raw material conservations were recorded; carbon dioxide costs and footprint were also reduced. Considering the RAC economic, technical, and environmental parameters, frameworks were applied for sustainable selections with target compressive strengths as the major goal.

Recycled concrete aggregates (RCA) are used in existing green building composites to promote the environmental preservation of natural coarse aggregates (NCA). Besides, the use of RCA leads to potential solutions to the social and economic problems caused by concrete waste. It is found that insufficient information on the longevity and sustainability of RCA production is a serious issue that requires close attention due to its impact on changing aspects of the sector. However, more attention has been paid to explaining the effect of RCA on concrete durability, as well as the properties of fresh and hardened concrete. Therefore, this study aims to provide a critical review on the RCAs for the production of high-performances concrete structures. It begins by reviewing the source, originality, types, prediction of service life, features and properties of RCA, as well as the effect of RCA on concrete performance. In addition, this literature review summarizes the research findings to produce complete insights into the potential applications of RCA as raw, renewable, and sustainable building materials for producing greener concrete composite towards industrializing ecofriendly buildings today. Further, it has also highlighted the differences in the current state of knowledge between RCAs and NCAs, and offers several future research suggestions. Through this critical and analytical study, it can be said that RCA has the possible use in the production of high-performance structural concrete depending on the source and type of recycled aggregate while the RCA can be used widely and safely to produce traditional green concrete.