Clay Brick Powder Research Articles

Preparation and properties of alkali-activated fly ash-waste brick porous building materials

This study explores the development of sustainable porous building materials through the alkali-activation of fly ash and waste clay brick powder. Utilizing Class F fly ash and brick powder from demolished buildings, a series of alkali-activated mortars with varying brick powder replacements (0 % to 50 % by mass) were formulated and analyzed. The results reveal that a 10 % brick powder replacement optimizes the compressive strength, reaching 73 MPa at 28 days, attributed to enhanced nucleation and calcium-rich gel formation. However, higher brick content reduces strength due to the dilution of key reactive materials, with a 50 % replacement leading to a strength of 27 MPa. Porosity increases proportionally with brick content, achieving a maximum of 42 % at 50 % replacement, suggesting potential applications in insulation-centric scenarios. Microstructural analysis confirms the formation of a porous network and identifies the phase compositions and reaction products. This research demonstrates the potential of repurposing construction waste into efficient and environmentally friendly building materials, contributing to waste reduction and offering a greener alternative to traditional practices.

Exploring the Potential of Using Waste Clay Brick Powder in Geopolymer Applications: A Comprehensive Review

Exploring the Potential of Using Waste Clay Brick Powder in Geopolymer Applications: A Comprehensive Review

Effect and mechanism of recycled clay brick powder on compressive strength of different types of concretes

To investigate the effects of recycled clay brick powder (CBP) partially replacing cement in different types of concretes, and reveal the combined influencing mechanisms of CBP with the water-to-binder (W/B) ratio, additives like water reducers, viscosity modifying agent, and fibers in concrete, the compressive strengths of eight types of concretes with different CBP contents were tested, and their hydration heat, pore structures and microscopic morphologies were examined. The results showed that for the concretes with a higher W/B ratio or with polycarboxylate superplasticizer (PCE) added, the internal curing effect of CBP was insignificant, and the compressive strength monotonically decreased with an increase in CBP replacement ratio; while the strength of concrete with a lower W/B ratio and without PCE did not always decrease with CBP content due to the significant internal curing effect of CBP, which made the reduction in strength at the same CBP replacement ratio less than that observed in concrete with a higher W/B ratio. For example, replacing cement with 30 % CBP caused the 28-day compressive strength of concrete to decrease by 25.2 % at a W/B ratio of 0.5, whereas at a W/B ratio of 0.33, the strength only decreased by 14.2 % compared to concrete without CBP. For concrete with PP fibers, the reduction in compressive strength induced by CBP replacement was mitigated, especially at a larger CBP replacement ratio, due to the bridging effect provided by PP fibers penetrated the micropores of CBP. For the concrete with hydroxypropyl methylcellulose (HPMC), replacing cement with 30 % CBP hardly reduced the concrete's compressive strength. The filling of CBP particles into the macropores introduced by HPMC reduced the pore sizes and offset the negative impact of the lessening in available reactive cementitious materials, and thus reducing the influence of CBP content on the strength. This study can serve as a reference for the utilization of CBP in cementitious materials, thereby facilitating the recycling of CBP in engineering applications.

Effect of waste clay brick powder on microstructure and properties in blended oil well cement pastes at HTHP conditions

The use of waste materials to improve the thermal stability of oil well cement (OWC) at high temperature and high pressure (HTHP) conditions has received increasing attention. This study investigated the performance of sustainable blended OWC pastes by recycling waste clay brick powder (CBP) as a partial substitute for commercial high temperature resistant additives (silica flour, SF). The main objective was to assess the impact of these substitutions on the hydration, microstructure and mechanical properties of blended OWC. CBP was incorporated at substitution rates of 25 wt%, 50 wt%, 75 wt% and 100 wt% by weight of SF. These pastes were firstly precured at 50 °C for 7 days (to simulate the primary cementing operation prior to steam injection), and then thermally cycling cured at 300 °C/13.0 MPa (to simulate the steam injection process). The study conducted comprehensive tests and analyses, including compressive strength, gas permeability, hydration products and microstructural analyses. The results showed that the suitable substitution rate of CBP in this study was 25 wt%-50 wt%. At these substitution levels, the blended OWC pastes had good compressive strength (18.5 MPa and 17.9 MPa) and low gas permeability (3.1 × 10−3 mD and 4.51 × 10−3 mD). From the environmental and economic analyses, the energy intensity and CO2 emissions of all blended OWCs were significantly lower compared to those of conventional OWC. Meanwhile, the cost of blended OWC in this study was significantly lower compared to that of the commercial SF-OWC system. Overall, this study highlighted the potential of recycling waste materials to promote raw material sustainability and improve the performance of OWC pastes at HTHP conditions.

Influence of Solid Waste Material Content on the Properties of Steel Slag-Waste Clay Brick Ceramic Bricks

Steel slag and waste clay brick are two common solid wastes in industrial production, and their complex chemical compositions pose challenges to the production of traditional alumina silicate ceramics. To investigate the influence of steel slag and waste clay brick on the performance of CaO–SiO2–MgO ceramic materials, this study examined their effects on the mechanical properties, crystal composition, and microstructure of the ceramics through single-factor experiments. The results demonstrate that when keeping the dosage of waste clay brick and talcum powder constant, a 43% dosage of steel slag yields optimal performance for the ceramic materials with a modulus of rupture of 73.01 MPa and a water absorption rate as low as 0.037%. Similarly, when maintaining a constant dosage of steel slag and talcum powder, a 41% dosage of waste clay brick leads to superior performance of the ceramic materials, with a modulus of rupture reaching 82.17 MPa and a water absorption rate only at 0.071%. Furthermore, when keeping the dosage of steel slag and waste clay brick constant, employing a talcum powder dosage of 24% results in excellent performance for the ceramic materials with a modulus of rupture measuring 73.01 MPa while maintaining an extremely low water absorption rate at only 0.037%. It is noteworthy that steel slag contributes to akermanite phase formation while talcum powder and waste clay brick contribute to diopside phase formation.

Reusing waste clay brick powder for low-carbon cement concrete and alkali-activated concrete: A critical review

The utilization of the waste clay brick powder (CBP) as an alternative binder in cementitious materials is an effective approach to recycling clay brick waste. Many research articles have been published on concrete containing CBP, but a systematic review on the performance of CBP and its blended concrete has been lacking until now. Therefore, the purpose of this article is to provide a comprehensive review of the utilization of CBP for low-carbon cement concrete and alkali-activated concrete, offering readers an effective pathway to understand its performance. This review article provides a detailed introduction on the preparation technology of CBP, as well as the micro-macro properties of cement concrete and alkali-activated concrete incorporating CBP. The results showed that CBP with irregular micro-structure is rich in silicon, aluminum, and oxygen elements, and exhibits good pozzolanic activity and micro-aggregate filling effect. Optimizing CBP particle size, replacement rate and curing condition can prepare the cement concrete with good micro-macro properties. Besides, there is an optimal CBP replacement rate, alkali concentration, Na/Si and Si/Al molar ratios for the alkali-activated concrete containing CBP. The mix of CBP in concrete obviously reduces the CO2 emission and energy consumption, showing an excellent environmental benefit. The mechanical activation treatment, active admixture and nano-particle modification can improve the properties of CBP blended concrete. In the future, CBP can be widely used in 3D printed concrete, high performance and ultra-high-performance concrete, lightweight concrete, fully recycled concrete and CO2 sequestration concrete.

Evaluating Techno-Eco-Efficiency of Waste Clay Brick Powder (WCBP) in Geopolymer Binders

The global focus on geopolymer binder production has increased due to the adoption of waste materials and industrial byproducts. Given the gradual decline in the availability of fly ash and ground granular blast furnace slag (GGBFS) resulting from the decarbonization process in electricity and steel production, waste clay brick powder (WCBP) could be a viable substitute for these pozzolanic by-products. This study presents the economic and environmental benefits of the use of WCBP as a replacement for conventional pozzolanic by-products in geopolymer binder production by assessing its techno-eco-efficiency, environmental impact, and cost-effectiveness performances. The favorable mechanical characteristics exhibited by the fly ash–GGBFS–WCBP-based geopolymer binder emphasize the importance of assessing its sustainability alongside its technical viability. The study employed life cycle analysis (LCA), following ISO framework, and using the Simapro software 9.2, to evaluate the environmental implications of the use of WCBP-based geopolymer mixtures. Human toxicity emerged as the primary impact. Moreover, the analysis of life cycle costs highlighted key financial factors, with around 65–70% attributed to alkaline activators of the total cost. The production of alkaline activators was identified as a critical point for both environmental impact and economic considerations due to energy consumption. While WCBP-rich samples exhibit a 1.7–0.7% higher environmental impact compared to the control mix (CM), their high mechanical strength and cost-effectiveness make them technologically and economically efficient geopolymer mixes. In conclusion, the portfolio analysis for techno-eco-efficiency affirms that mixes containing 40%, 30%, and 20% WCBP are more efficient than those using 10% and 0% WCBP, respectively.

Development of nano-silica modification to enhance the micro-macro properties of cement-based materials with recycled clay brick powder

Utilizing recycled clay brick powder (RCBP) as alternative binder provides an effective method for reducing the amount of the clay brick waste and the need for cement, but incorporating high volume of RCBP generally causes a reduction in the performance of cement-based materials. Considering that the nano-SiO2 (NS) is commonly used and highly efficient modification materials for cement-based materials, this paper developed the NS modification to enhance the performance of cement-based materials containing RCBP. Mixing RCBP negatively impacts the hydration reaction and hydration products, but adding NS accelerates the hydration process and the formation of hydration products in RCBP paste. Adding 0.5% and 2.0% NS causes 27.3% and 43.3% increase in the cumulative heat of 30% RCBP blended paste. The mix of NS can refine the pore structure of RCBP paste, and causes a distinct reduction in the percentage of the most harmful pore. The nanoindentation results show that adding NS can raise the elasticity modulus and indentation hardness of RCBP paste. Substituting RCBP for partial cement reduces the drying shrinkage, but mixing NS increases the drying shrinkage of RCBP paste. Incorporating RCBP leads to a decline in mechanical strength, nonetheless, the mechanical strength of RCBP paste rises with the increasing dosage of NS. Adding 2.0% NS results in 44.2% and 18.8% enhancement on the 1-d and 28-day compressive strength of 30% RCBP blended paste. By optimizing the dosage of RCBP, NS and mineral admixtures, it is possible to fabricate sustainable cement-based materials exhibiting good strength and permeability resistance.

Characterization of Waste Clay Brick Powder and its Effect on the Mechanical Properties and Microstructure of Geopolymer Mortar

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

Study on the performance and reaction mechanism of alkali-activated clay brick with steel slag and fly ash

This study aims to enhance the utilization of clay bricks by maximizing the application of clay brick (CB) powder. The amount of CB was set at 50% and different percentages of steel slag (SS) powder and fly ash (FA) are added. A CB-SS-FA ternary hybrid geopolymer was prepared through alkali activation, and its performance and reaction mechanisms were investigated. The main parameters used to evaluate the performance under different proportions were volume stability and compressive strength. The microstructure and reaction mechanism were analysed using SEM/EDS, ICP, isothermal conduction calorimetry (ICC), FTIR, XRD, and TG-DTG. The experimental results illustrated that SS provided early compressive strength to the CB-SS-FA system. CB has low activity, but Anorthite within can participate in the reaction. CB provides more Si and Al to the system than FA within 1d at room temperature. FA dissolved at a relatively high rate at 80 ℃, and then supplied Al and Si to the system continuously. FA and CB cooperate to promote the dissolution of Ca2+ in steel slag. CB provide adhesion sites for the generated gel. Moreover, its porous microstructure can provide space to release expansion energy from f-CaO. The optimal content of SS is 30% in this ternary geopolymer. C-(A)-S-H and N-A-S-H gels were formed that wrapped the partially hydrated clay brick and provided strength to the system.

Experimental Study and Mathematical Modeling of Mechanical Properties of Basalt Fiber-Reinforced Recycled Concrete Containing a High Content of Construction Waste

Herein, we conducted an experimental test on basalt fiber-reinforced concrete with a high content of construction and demolition waste and then established some mathematical models based on Taylor’s formula. The concrete was prepared by using recycled clay brick powder in place of cement and recycled coarse aggregates as a substitution for natural coarse aggregates. The basalt fiber in weight dosages of 0, 0.1, 0.3, and 0.5% was used for reinforcement. The results showed that the compressive strength of concrete declined as the content of recycled aggregates increased, while the compressive strength first increased and then decreased as the basalt fiber dosage lifted. Regarding the splitting tensile strength, the reinforcement effect of basalt fiber in concrete with a high content of recycled aggregate is more significant when compared to its to its counterpart, which contains no or fewer recycled aggregates. The concrete with 0.5% basalt fiber dosage and 100% recycled aggregate content retains an equivalent compressive strength as to that of natural aggregate concrete and has about a 90% splitting tensile strength. In addition, the cubic function in comparison to the quadratic function has a higher fitting accuracy.

Durability, Microstructure, and Optimization of High-Strength Geopolymer Concrete Incorporating Construction and Demolition Waste

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%.

Major and minor elliptical axes and bounding rectangle dimensions in clay brick powder particles from changing milling conditions

Starting from the observation that regular shape parameters such as equivalent diameter, area-perimeter ratio, circularity, compactness and roundness fail to adequately identify shapes of materials, alternative shape parameters are proposed to remedy this shortcoming. In this study, plugins in image analysis are extended to explore the major and minor elliptical axes and bounding rectangle dimensions in clay brick powder particles from changing milling conditions of different masses of clay bricks in ball mill. It turned out that with developed plugins in ImageJ, extracting such shape parameters of clay brick powder samples was not problematic. For the generated reciprocal aspect ratio (RAR) values ranging from 0.51 to 0.53, majority of the particles were noticed to be within the ellipse-inclined shapes. Using the feret major axis ratio (FMR) values for the formulated bounding rectangle dimensions, most particles appeared to be bound in rectangle-inclined shapes. Despite the generated major and minor elliptical axes and bounding rectangle parameters, grinding conditions in this research did not present any significant influence on such shape parameters of CBP specimens. It is believed that the developments of quantifying the major and minor elliptical axes and bounding rectangle dimensions of the CBP particles in this study are ground on solid foundations without need for extensive experimental works. The proposed developments are therefore valid and could be dedicated for characterising pozzolanic materials, because of their interests in cement-based composites.

Recycling of clay brick powder to improve the microstructure and mechanical properties of oil well cement pastes at high temperature and high pressure conditions

In oil well cementing involving high temperature and high pressure (HTHP), silica sources are usually incorporated into oil well cement to prevent its strength retrogression. This paper aims to use recycled clay brick powder (CBP), a silica-enriched material, as an alternative to the use of silica flour (SF) to inhibit the strength retrogression of the cement pastes after thermal cycling curing at 300 °C/13.0 MPa. Pure pastes (G), blended pastes with 40 wt% SF (40SF) and blended pastes with 40 wt% CBP (40CBP) were prepared to comparative analysis. The results showed that 40CBP and 40SF exhibited lower compressive strength and poorer pore structure than the G samples at 50 °C. However, the incorporation of CBP could effectively improve the compressive strength of the cement at 300 °C/13.0 MPa compared to that of the G paste. Mineralogical analysis indicated that xonotlite phases were the main crystalline phases in 40CBP and 40SF after thermal cycling curing. Compared to reinhardbraunsite in G samples, xonotlite could improve the pore structure and make the microstructure denser. In addition, there are some hibschite phases in 40CBP, which may make its compressive strength slightly lower than 40SF. Nevertheless, the environmental impact and cost analysis showed that the energy intensity and CO2 emissions of 40CBP were significantly lower than those of G and 40SF, and it had great cost advantages. This study is expected to provide some help in the rational recycling of CBP and reducing the CO2 emissions in cement production.

The Impact of Brick Powder Specific Surface Area on Cement Replacement in Mortar Mixes: A Sustainable and Cost-effective Solution for the Construction Industry

This study examined the use of clay brick powder (CBP) as a partial substitute for cement in mortar mixes. Five mixes were tested, each differing by the fineness of the CBP, obtained by grinding brick waste for different durations (30, 60, 90, 120 minutes). Several parameters were evaluated; apparent density, porosity, spread, ultrasonic pulse velocity (UPV), flexural and compressive strength, and the pozzolanic activity index. The results indicate that, when the brick powder is ground for 60 minutes, the spread of the mortar exceeds 95% compared to the reference mortar. The addition of CBP appears to increase the water absorption and porosity of the mortars, without significantly influencing their apparent density. Most samples have a UPV close to 4000m/s, attesting to satisfactory mechanical properties. The use of 20% CBP in replacement of cement leads to a decrease in flexural strength. However, this drop is less when the specific surface area of the CBP is close to that of cement. As for compressive strength, a decrease is also noted with the introduction of CBP, but this decrease can be mitigated by using CBP with a specific surface area similar to that of cement. These factors can significantly influence the pozzolanic activity of the mortar mix. Furthermore, our investigations into environmental and economic analyses show that the use of cement mixes including CBP results in a significant decrease in energy consumption and CO2 emissions. More specifically, the replacement of 20% of cement with CBP of different granulometries has led to promising results.

Effective Use of Waste Plastic As Sand in Metakaolin/Brick-Powder Geopolymer Concrete

This study proposes recycling waste clay brick and waste polyethylene terephthalate (PET) bottles as substitution materials in geopolymer concrete. To accomplish this goal, the control mix of geopolymer concrete was prepared based on blended metakaolin and waste clay brick powder (CBP) at a 1:1 mixture by weight. To evaluate the use of shredded PET particles as fine aggregate, three mixtures were made by replacing sand with PET aggregate at volumetric percentages (10%, 15% and 20%). The specimens containing PET aggregate were tested and compared against the control mix (0% PET), with emphasis on the fresh and dry densities, mechanical performance, water absorption and microstructure characteristics. The results indicated the inclusion of PET aggregate to slightly reduce density and improve mechanical properties. When compared to the control mix, the compressive strength of the 20% PET replacement increased to 28.1 MPa after 28 days. Moreover, the concrete with 20% PET obtained the lowest water-absorption rate. The scanning electron microscopy images revealed that the inclusion of waste PET as sand had a significant effect on the microstructure of Mk-CBP geopolymer concrete. When compared to the control mix, the matrix containing 20% PET had a denser microstructure, as well as fewer holes and microcracks, in addition to the packing of paste at the interfacial transition zone. KEYWORDS: Brick powder, Fine aggregate, Geopolymer concrete, Metakaolin, Polyethylene terephthalate (PET).

Recycled mineral admixtures based on recycled clay brick

The utilization of construction demolition waste as recycled mineral admixtures can simultaneously reduce cement consumption and the environmental impact on the construction industry. Thus, recycled mineral admixtures based on recycled clay brick powder (CBP) were prepared and circulating fluidized bed combustion (CFBC) fly ash was introduced as the activity compensation and sulfate excitation component. The effects of the hydration of recycled mineral admixtures on the mechanical performance and drying shrinkage of mortar were investigated. The results indicated that the incorporation of CFBC fly ash into the blended cement paste accelerated the hydration of C3S and shortened the induction period. The fly ash also promoted the secondary hydration of C3A and the conversion of ettringite to the monosulfate phase. The CBP consumed portlandite to form a calcium–silicate–hydrate gel at a later age, whereas CFBC fly ash promoted the pozzolanic reaction to occur earlier. The incorporation of the CBP and CFBC fly ash increased the porosity and pore volume of the blended paste.

A contribution to debate on surface roughness of clay brick powder generated using varying milling treatments

Recently, the correlation between surface roughness and fineness of materials including pozzolans has been subjected to too much debate in literature. Exploiting the surface roughness of pozzolans has been proven to be significant for cement-based composites. Although research works have been conducted to assess the effects of milling treatments on surface roughness of pozzolans, limited dedicated studies have explored the use of multi-scale characterisation methods for analysing this complex parameter. In this research, an economic and novel technique was employed to characterise the surface roughness of clay brick powder (CBP) subjected to varying milling treatments of various sample masses. The main aim of this research was to investigate the correlations between fineness levels of CBP and surface roughness parameters. Characterisation of CBP generated from ball milling was performed using scanning electron microscopy (SEM) and Gwyddion. There was significant effort employed during the search for significant trends between roughness parameters and grinding clay bricks using different specimen masses, sadly without success. The results of amplitude roughness parameters, fast Fourier transformations, autocorrelation functions and power spectral density functions demonstrated no significant trends for CBP specimens generated under varying specimen masses. Although CBP specimen with highest fineness level seemed to illustrate the lowest roughness characteristics in some cases (i.e. root mean square roughness of 159.182 nm and mean roughness of 115.444 nm), CBP specimen with lowest fineness level did not illustrate the highest surface roughness properties. Through the analyses, it seemed that CBP specimens subjected to different fineness levels could not illustrate significant differences in surface roughness properties and this observation is contrary to some findings in literature. It is believed that the algorithms used for surface roughness characterisation in this research facilitate the understanding of surface roughness properties of CBP specimens subjected to different fineness levels.

Effect of Clay Brick Waste Powder on the Fresh and Hardened Properties of Self-Compacting Concrete: State-of-the-Art and Life Cycle Assessment

Sustainability and reducing environmental damage caused by CO2 emissions have become issues of interest to researchers in the construction sector around the world. Reducing the cement content in concrete by partially substituting it with by-products or waste falls within this field as the cement industry is responsible for 7% of global CO2 emissions. On the other hand, self-compacting concrete (SCC) is one of the special types of concrete that contains a large amount of powder (most of which is cement) to ensure its flow under the influence of its weight without separating its components. Therefore, to produce eco-friendly SCC, many researchers have replaced part of the cement with clay brick waste powder (CBWP) since brick units are among the most widely used building materials after concrete. Accordingly, this study aims to review previous research that included using CBWP in SCC. The effect of these wastes on the fresh, mechanical, durability and microstructural properties of cement was reviewed. Additionally, a comparison between the environmental impacts of SCCs with different CBWP contents has been conducted using the life cycle assessment (LCA) approach. It was found that the highest value of CBWP that can be used without negatively affecting the different properties of concrete is 10% by weight of cement. Moreover, regarding environmental impact, using CBWP as a substitute for cement reduces environmental damage, and the lowest environmental impact that can be achieved per strength unit (MPa) is 37.5%.

Properties of concrete mixes containing tire rubber and brick powder exposed to sulfuric acid and cured in water: A comparative study

The existing literature shows that rubberised concrete suffers from reduced mechanical properties when it is compared with normal density non-rubberised concrete. This is due to the underlying reduced bonding between tire rubber and other concrete ingredients. The massive sulfuric acid attack in rubberised concrete must have additionally discouraged researchers from attempts to assess the phenomenon of improving performance of rubberised concrete. A research was undertaken to compare the properties of concrete mixes containing tire rubber replacing coarse aggregate and waste clay brick powder (WCBP) replacing cement exposed to sulfuric acid and cured in water. Concrete cubes and cylinders of concrete grades of 20 MPa, 25 MPa and 30 MPa were immersed in 5% sulfuric acid solution up to 90 days following moist curing of 27 days. Other concrete cubes and cylinders were cured in water for comparison. The compressive strength findings indicated that all the specimens exposed to sulfuric acid had lost more than 57% of their compressive strengths after 90 days with reference to the corresponding samples cured in water. In contrast, out of all concrete mixes investigated for all concrete grades, never were the split tensile strength losses of the specimens exposed to sulfuric acid greater than 43.1% compared with those cured in water. In each exposure condition, concrete mixes with 5% WCBP showed slight improvements in compressive and split tensile strengths in contrast with the conventional concrete mixes. Visual inspection of the specimens illustrated depositions of flaky or white substances on the outer layers of specimens exposed to sulfuric acid compared with specimens cured in water. Moreover, the split tensile strengths of specimens were not severely affected with exposure to sulfuric acid in comparison with compressive strengths. Eventually, the research identified the existence of WCBP in rubberised concrete as a promising criterion of minimising strength losses of rubberised concrete.