Replacement Of Natural Fine Aggregate Research Articles

Upcycling of End-of-Life-Vehicle (ELV) plastics as a replacement for natural fine aggregate in concrete

End-of-life vehicle (ELV) plastics pose technical challenges in conventional recycling due to their diverse polymer compositions. Consequently, landfilling remains the prevailing disposal method. This study explores an innovative approach by upcycling ELV plastics as a substitute for natural sand in concrete. The study investigates the physical, mechanical and economic performance of ELV plastic-containing concrete. Plastic aggregates were prepared from real-world ELV plastics, featuring particle sizes below 4.75 mm, with over 90 % falling within the range of 1.18–4.75 mm. The research involves replacing natural sand with ELV plastics at varying volumes (0 %, 15 %, 25 %, 35 %, and 40 %) and examines the effect of sand replacement on various concrete properties. The results suggest that as the replacement ratio increases, the workability, density, and strength of concrete decrease. However, the 28-day compressive strength of concrete at the maximum replacement rate of 40 % was found to be 39 MPa, which suffices for certain non-structural strength applications, such as traffic routes, shared-use paths, local streets and curbs. In addition, compared to previous studies using mixed commodity plastics, ELV plastics lead to significantly lower strength reductions at high replacement ratios. Scanning Electron Microscopy (SEM) analysis reveals a distinctive rough and fibrous aggregate morphology, which enhances physical binding and provides bridging effects within the concrete matrix, potentially mitigating strength loss. Moreover, the economic analysis highlights a significant potential to commercialize ELV plastics for concrete applications. This study demonstrates that ELV plastics can be effectively used at high replacement rates (up to 40 % by volume) in non-structural applications.

Performance of cement mortar mixes containing fine reclaimed asphalt pavement aggregates and zinc waste

Cement mortar mixes were prepared to test the suitability of fine reclaimed asphalt pavement (FRAP) aggregates as a replacement for natural fine aggregates (NFA). With different amounts of NFA (25%, 50%, 75% and 100% by weight) replaced with FRAP aggregates, the mechanical qualities of the mortar mix deteriorated. To counteract this, jarosite – a waste from the zinc industry – was used as a partial replacement for cement (replacements of 5%, 10% and 15%). The jarosite improved the microstructural, mechanical and shrinkage properties. For example, compared with the control mix (100% NFA), the mix containing 25% FRAP aggregates showed a 5.5% reduction in hardened density and a 14% reduction in compressive strength. With the addition of 10% jarosite, there was an increase of 4.85% in hardened density and 7% in compressive strength with respect to the mix containing 25% FRAP aggregates. It is thus suggested that 10% jarosite is used when FRAP aggregates are used to make cement mortar mixes. A cost analysis was also performed. The findings of this work are expected to inspire rational mix design recommendations for mortar mixes including FRAP aggregates, as well as bringing environmental and economic benefits by reducing carbon dioxide footprints.

Resistência à penetração de cloretos em concretos produzidos com agregado miúdo reciclado e sílica ativa

Abstract The use of by-products and recyclable materials in the production of concrete has become an interesting alternative to mitigate environmental impacts, especially those generated by the construction industry, as long as their mechanical and durability properties do not early compromise the service life of the structures. The resistance of concrete to the penetration of harmful agents, such as chloride ions, is an important property since it directly correlates with the performance, integrity, and durability of reinforced concrete structures. This study evaluate four concrete mixes were cast for aggressiveness class III of NBR 6118 [1] produced with 8% of partial replacement of Portland cement with silica fume, resulting of metallurgical production, and with 30% partial replacement of natural fine aggregates by recycled fine aggregate from fresh concrete waste, obtained from the concrete production process in concrete mixer trucks. At 28 days of age, the specimen was submitted to capillarity, mechanical resistance and chloride migration tests, according to the NT BUILD 492 standard [2]. In general, the results indicated that the proposed replacements improved mechanical properties and chloride ion penetration resistance, mainly with the incorporation of silica fume.

Carbonation and permeation behaviour of geopolymer concrete containing copper slag and coal ashes

The current study primarily evaluates the carbonation and permeation resistance of coal bottom ash (CBA) and copper slag (CS) based geopolymer concrete (GPC). The strength parameters along with non-destructive tests were also performed for reference. CS and CBA were used as a 10%, 30% and 50% replacement of natural fine aggregates (NFA). Fly Ash (FA) was used as a binder and all seven mixes were subjected to oven curing at 65 °C for 24 h. The molarity of NaOH was kept constant (12 M) along with Sodium Silicate/Sodium Hydroxide ratio of 2. With inclusion of CS the carbonation depth, initial and capillary absorption has been decreased by 30%, 23% and 19% respectively with respect to control mix. The above-mentioned values have been increased by 28%, 27% and 58% in CBA based GPC. GPC mix containing 30% replacement of CS as sand has been considered to be appropriate for carbonation and permeation aspects.

Reusing Ceramic Waste as a Fine Aggregate and Supplemental Cementitious Material in the Manufacture of Sustainable Concrete

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.

Experimental assessment of utilizing copper tailings as alkali-activated materials and fine aggregates to prepare geopolymer composite

Globally, there is an increasing attention drawn by copper tailings (CT) due to the environmental problems caused by its tremendous storage volume and low recycling rate. With the purpose of promoting the sustainability and value-added utilization of CT, this study used CT powder with particle size ≤ 0.075 mm, granulated blast furnace slag (GBFS), and fly ash (FA) to prepare CT/FA-GBFS geopolymer paste composites. Also, 0.075–0.6 mm CT sand was also used as a replacement of natural fine aggregates. The effect of CT powders on the mechanical strength of the geopolymer paste was assessed, as well as the influence of CT sand on the mechanical strength and the heavy metal leaching behavior of CT-GBFS geopolymer mortar. The obtained results from the study demonstrate that CT powder exhibits partial participation in the geopolymerization reaction within an alkaline environment. Additionally, it manifests a filling effect when incorporated as micro powders. It is noteworthy that the compressive strength of the geopolymer paste improved by 18% and the flexural strength by 74% when the CT content reached 45%. Furthermore, in the context of CT-GBFS geopolymer mortar, the 20% replacement ratio of CT sand yields a more favorable interfacial transition zone (ITZ) between the geopolymer paste and the mixed sand. This improved ITZ improves the mechanical properties of the mortar by about 10% compared to other experimental groups. Finally, when CT were immobilized in the CT-GBFS geopolymer mortar, the leaching of heavy metals from copper tailings was significantly reduced, eliminating the impact of CT utilization on the environment.

Sustainable utilization of mixed healthcare waste as aggregate in lightweight concrete mixes: mechanical behavior, water absorption and leaching studies

Wastes generated from healthcare practices are a serious problem for humans as well as for the environment. In this study, an attempt was made to use mixed solid medical waste (WPN) which consisted of shredded waste plastic and chopped waste needles for partial replacement of natural fine aggregate (sand) in concrete mixes at 0%, 2%, 4%, 6%, 8% and 10% by weight. To examine the validity of the suggested approach, the fundamental concrete properties including workability, fresh and hard densities, water absorption, compressive strength, and flexural strength as well as a leaching test were performed. The curing ages for the concrete mixes were considered to be 7, 14, and 28 days. Fifty-four cubes were molded for compressive strength test, and 72 prisms were cast for flexural strength, whereby 162 cubes were prepared for density tests as well as water absorption test. The results revealed that WPN-concrete mixes exhibited improvement in the workability and steadily decreased both the compressive and flexural strength values of the WPN-concrete mixes which were higher than the mean target strength of lightweight concrete grade M17. Leaching test results indicated the absence of the target components in the leachant. The outcomes of this experimental study demonstrated that reusing WPN as a sand-substitution aggregate in concrete is a good approach to reducing the adverse impact resulting from the improper management of healthcare and medical solid waste.

Evaluation of real time fire performance of eco-efficient fly ash blended self-consolidating concrete including granite waste

Manufacturing of granite products generates enormous amounts of granite waste (GW) worldwide, which triggers environmental pollution on its dumping. On the other hand, the resistivity of concrete structures and the safety of humans are likely to undergo intense threats when exposed to fire attacks. Therefore, an experimental study was conducted to determine the real-time fire attack performance of eco-efficient fly ash blended self-consolidating concrete (SCC) containing up to 60% GW as a replacement for natural fine aggregate. The change in weight, compressive strength, water absorption, and ultrasonic pulse velocity characteristics of SCC were determined after being exposed to varying elevated temperatures of 200 ± 10 °C, 400 ± 10 °C, 600 ± 10 °C, and 800 ± 10 °C. Advanced Fourier transform infrared test was done to examine chemical changes in fire-exposed specimens. Test results revealed that FA blended SCC containing GW (up to 60%) exhibits better post-fire properties, with optimum mechanical and durability properties at 30%. Besides, sustainability analysis results revealed that the use of GW up to 40% exhibited better sustainable solutions under the given economic and environmental cost factors. This study concluded that up to 40% GW as a replacement to fine aggregate could be positively incorporated in the production of FA blended SCC, where failure due to fire is a problem.

Performance evaluation on bond, durability, micro-structure, cost effectiveness and environmental impacts of fly ash cenosphere based structural lightweight concrete

The production of huge fly ash waste from thermal power plants and gradual depletion of natural aggregates due to their high consumption in concrete making are two major threats to the sustainability of the environment. The strategic utilization of this waste as a replacement of natural aggregate in production of concrete can solve both the problems simultaneously. Hence, this study aims to evaluate the performance of structural lightweight concrete (LWC) containing fly ash cenosphere (FAC), a by-product of fly ash, in order to check its suitability for construction. In this study, one control concrete mix, i.e., without FAC, and other ten concrete mixes utilizing FAC as the replacement of natural fine aggregate (NFA) at the increment of 20% and with/without superplasticizer (SP) are prepared. The Mechanical properties (compressive and bond strength), durability aspects (sulphuric acid, magnesium sulphate and sodium chloride resistance) and the microstructural characteristics from X-ray diffraction and scanning electron microscope analyses of these mixes are evaluated. Moreover, the environmental impact assessment and cost-effective analysis are also conducted. From this investigation, it is found that the structural LWC can be produced by utilizing high volume FAC with/without SP with the acceptable mechanical and durability performances. Further, the concrete with 80% FAC and SP is found to be optimum having compressive strength of 32.59 MPa, which satisfies M25 grade concrete as per IS 456 (2000), meets ACI 213 (2014) requirements of structural LWC and has also acceptable durability properties. The microstructure studies have also supported the strength and durability results of these mixes. Moreover, these mixes are found to be cost effective and environmentally friendly. Hence, structural LWC prepared with a high volume of FAC and SP can be recommended for construction, which reduces the cost and environmental impacts significantly and preserves natural resources for the future generations.

Improvement of mechanical properties and carbonation durability of recycled fine aggregate engineered cementitious composites for structural strengthening

External wrapping with engineered cementitious composite (ECC) extends the service life of concrete structures after reinforcement corrosion, but the low economics of this strengthening measure limits its application. In this study, recycled fine aggregate engineered cementitious composite (RFA-ECC) for structural strengthening was prepared using recycled fine aggregate (RFA) as a 100% replacement for natural fine aggregate (NFA). The effects of fiber and fly ash on the mechanical properties of RFA-ECC were investigated for component optimization design. Additionally, the carbonation durability of RFA-ECC with initial crack damage was investigated by a preloaded carbonation test, and a carbonation model of RFA-ECC was established. The results demonstrated that the compressive strength of ECC decreased by 13.75% when RFA replaced NFA completely, but the flexural strength was still as high as 7.2 MPa. The self-cementing ability of RFA densifies the matrix microstructure, thereby enhancing the fiber bridging stress capacity. The tensile strength of RFA-ECC reached 2.5 MPa at 2% fiber volume fraction, which was 5.77% higher than that of natural ECC. The increased fly ash content enhanced the matrix strain capacity, but the tensile strength decreased significantly. The economic analysis indicates that RFA-ECC, with a 1.5% fiber volume fraction and 40% fly ash content, meets the performance requirements while offering a cost-saving of 15.4%.

Effect of using sugarcane leaf ash and granite dust as partial replacements for cement on characteristics of ultra-high performance concrete

A significant quantity of cement is necessary for the production of ultra-high-performance concrete (UHPC). However, some environmental issues are associated with cement production. The worldwide agricultural growth increases ash from agricultural waste (AW). Furthermore, industrial waste (IW) generated throughout the stone-cutting and processing has increased due to the growing demand for granite stone in construction. This research conducted a unique study that involved comparing the use of sugarcane leaf ash (SLA) as AW and granite dust (GD) as IW as partial substitutes for cement in the production of eco-friendly UHPC. The effect of employing SLA and GD with replacement ratios ranging from 20% to 50% on the mechanical and transport properties of UHPC was studied. In addition, this research investigated the effectiveness of partial replacement of natural fine aggregate (NFA) by recycled fine aggregate (RFA) with ratios ranging from 25% to 100% on the UHPC qualities. Moreover, the effect of elevated temperatures on the UHPC and the microstructural examination were investigated. Results demonstrated that the optimum replacement ratio of SLA or GD from cement was 20%, showing the best mechanical characteristics of the UHPC. For example, after 28 days of casting, the compressive strength increased by 12.16% and 8.44% when SLA and GD were added to the UHPC mix, respectively. Additionally, the 25% replacement ratio of RFA from NFA presented the best mechanical and transport properties of the UHPC. The mixes containing SLA positively affected the UHPC higher than those containing GD.

Comparative Study of Concrete Using Recycled Fine Aggregate

Abstract: Waste handling and management is the major problem faced by countries in the modern era. Concrete demolition waste has been one of the sources of creating environmental pollution. There have been many strength and durability studies taking place to analyze the concrete made with fine aggregate which has been recycled from old concrete structures and proved high strength compared to the concrete made with new materials. Those research works are limited in analyzing finer divisions of the concrete made with the aggregates which have been recycled. This paper concentrates on the applications of recycled Fine Aggregate (RFA) as a partial replacement instead of the fine aggregates available naturally to prepare the concrete. With a view to the above needs, the present study is aimed to determine the strength properties of RFA concrete depending on the various content of RFA and to compare them to the strength properties of concrete made with natural fine aggregates (NFA). Fine aggregates of high FM of 2.6 were used for recycled and natural concrete. After performing the compressive strength test with partial replacements of 30%, 40%, 50%,60%,70% and 80%of RFA with NFA, it was found that concrete made with the following replacements RFA has less strength than concrete made with NFA but with not much difference. So, RFA can be used as a replacement for NFA in concrete production. In addition, partial replacement of RFA can be used in structures of less importance such as temporary walls, the base of roads, light traffic roads, pavements in college campuses etc.

Influence of aluminum waste on the thermo-mechanical properties of lightweight composite mortars based on sand and recycled high-density polyethylene

The development of new construction materials must take into consideration several factors, including the environmental impact, cost price, mechanical performance and thermal comfort. The present study falls within this context. It essentially aims to valorize high-density polyethylene plastic waste as a fine aggregate in substitution of sand at 10% and 30% in order to produce lightweight composite mortars. The incorporation of aluminum waste (powder), which is as an expansive agent, was made at 0.5% and 1% of cement weight in order to further lighten the products that are primarily intended for thermal insulation. This study also seeks to investigate properties in the fresh state such as the workability of mortar, and other properties in the hardened state such as the density, the compressive strength and tensile strength by bending, and finally the thermal conductivity. The results obtained showed that the density of the product obtained decreased as a function of the rate of replacement of natural fine aggregates by high-density polyethylene and also of the aluminum content. In addition, it was observed that the mechanical strengths decreased while the thermal conductivity of the composite mortars obtained improved significantly by approximately 48% in comparison with that of the control mortar.

Evaluating resistance of ceramic waste tile self-compacting concrete to sulphuric acid attack

Ceramic waste tile aggregates produced from mixed coloured tile were utilized in self-compacting concrete (SCC). This research was aimed at assessing the performance of SCC in sulphuric acid environment by introducing ceramic waste tile (CWT) as natural fine aggregate replacement in different ratios (0%, 20%, 40%, 60%, 80% and 100%). SCC samples were exposed to a 3% sulphuric acid solution for 7, 28, 90 and 180 days. The transformation of mass, compressive strength, and micro-structure were used to assess the performance of concrete. It was discovered that CWT was sacrificial in nature when the SCC samples were subjected to an acidic environment, which helped to prevent damage to the cement hydration components that provided the strength. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that the presence of CWT led to substantially less damage to the hydration products. Furthermore, the increment in replacement level after 60% has shown an increment of void ratio, leading to reduction in preliminary mechanical characteristics. It was concluded that 60% replacement level may provide the highest optimum performance in terms of compressive strength and sulphuric acid resistance. According to economic and ecological studies, SCC mixtures that comprise CWT are economical and have lower embodied energy and lesser CO2 emissions.

Experimental studies on mechanical properties of concrete by using artificial fine aggregate and as replacement of natural fine aggregate for sustainable development

Concrete is the second most used material on the earth after water. The current era of concrete making material like the coarse and fine aggregate need alternatives to overcome the demand. In this present study, artificial fine aggregate or artificial sand (AS) as an alternative to fine aggregate has been investigated. The parameters studied in this study to investigate the AS effect of concrete are slump, modulus of rapture, compression strength, split-tensile strength, and shear strength. The experimental results show that the fresh properties and compression strength show significant changes when the replacement dosage of natural fine aggregate or natural sand (NS) increases with AS. However, the other parameters, namely shear strength, tensile strength, modulus of rapture, and AS replacement, also positively impacted concrete. The multi-criteria decision-making technique was used to determine the prepared mixtures’ optimum mixture. Based on TOPSIS analysis, it is confirmed that the replacement of AS is 25% more effective. The study revealed that 100% NS replacement is also possible by AS, but a suitable admixture is required for workability.

Influence of waste refractory brick on the destructive and non-destructive properties of sustainable eco-friendly concrete

Concrete is one of the most popularly used structural materials in the construction. It is a composite mixture of cement, fine aggregate, coarse aggregate, water, and with or without admixture. For concrete production, large amounts of natural aggregates are being consumed and as a result, the environment is facing severe challenges. The imbalance in the ecosystem is creating immense complications in the environment due to the illegal mining of aggregate from natural resources. Under these circumstances, researchers are finding suitable alternatives to preserve natural resources and raise environmental awareness and consequently the concept of sustainability is introduced. Depending on the level of difficulties, the utilization of waste materials may be exercised for the preparation of sustainable concrete that are economically and environmentally acceptable. Refractory Bricks turn out to be such a waste after a few cyclic usages in various thermal industries and may be utilized in concrete. In this present experimental work, the utilization of waste refractory bricks are proposed for the partial/total replacement of natural fine aggregate at 10, 20, 30, 40, 50, 70, and 100% levels by crushing it into fine particles. In this study, experiments are mainly divided into two parts, one is non-destructive tests and others are destructive tests. In non-destructive section, the prediction of compressive strength by Rebound Hammer has been performed. Subsequently, destructive tests, like Compression test, Flexural test, and Split Tensile test have been performed to check the mechanical properties of the concrete specimens. From the compression and split tensile test 20% replacement level provided the optimum result. The specimen with 30% replacement presented the best Flexural Strength. All the test results of sustainable concrete specimens are being compared with conventional concrete to check the enrichment or retrenchment of properties of concrete specimens with the incorporation of waste refractory bricks.

Effect of Addition of LD Slag Aggregate on Fresh and Hardened Properties of Cement Concrete

Cement concrete lends itself to a multitude of unique designs because of its many beneficial characteristics. Because of its inexpensive cost and desirable physical qualities, concrete is one of the most extensively utilised civil engineering materials. In this article, LD (Linz and Donawitz) slag is used to partially replace fine aggregate. This research mainly concentrates on partial replacement of natural fine aggregate with LD slag fine aggregate. Since the construction industry activity in India is gaining its momentum there is a scarcity of natural resources to overcome this problem substitute materials should be used to make the concrete and studies have to be conducted. In this study such an attempt is made where natural fine aggregate is partially replaced with LD slag fine aggregate. The purpose of this work is to investigate the fresh and hardened qualities of M-30 grade concrete in which LD slag has been partially replaced by the weight of natural fine aggregate in the ratios of 0%, 10%, 20%, 30%, 40%, and 50%. The slump test is used to investigate the features of workability. Compressive and split tensile strength tests are used to investigate the hardened characteristics of concrete. After 28 days of curing, the test is performed, and a mathematical regression model is constructed for the same.

Prediction and optimization of properties of concrete containing crushed stone dust and nylon fiber using response surface methodology

Over-extraction of aggregates from natural sources with rapid urbanization as well as massive waste generation in construction industry have imposed the need to utilize waste material as concrete constituent. Crushed Stone Dust (CSD) is such a supplementary material that can be utilized for the production of sustainable concrete. This study attempts to predict and optimize fresh and hardened properties of concrete utilizing CSD as a partial replacement of natural fine aggregate and Nylon Fiber (NF) as fiber reinforcement using Response Surface Methodology (RSM). A three-level factorial design of Box-Behnken was incorporated to investigate the effect of CSD, NF and W/C as three independent variables on compressive strength, splitting tensile strength, fresh density and workability of concrete as desired responses. All the developed probabilistic models were found to be significant in predicting the responses at 95% confidence level. Regression analysis in terms of correlation coefficient, coefficient of determination, coefficient of variation, adequate precision, chi-square, mean square error, root mean square error, and mean absolute error also indicated the accuracy and functionality of the developed models. The results reveal that both compressive and splitting tensile strength increase with increased NF content, but the rise in CSD percentages beyond a certain level has negative impact on strength of concrete. However, fresh density and workability of concrete show a declining trend with rise in both CSD and NF levels. From multi-objective optimization, 20% CSD, 0.75% NF and W/C of 0.49 have been found to be the optimum proportions for concrete mixture with a desirability of 0.915. Finally, an experimental validation was carried out with optimum mixture contents and relative error between the experimental and predicted optimized values was observed to be less than 5%.

Experimental investigation on the mechanical properties and damage evolution of steel-fiber-reinforced crumb rubber concrete with porcelain tile waste

The utility of crumb rubber concrete (CRC), a green concrete containing waste tire rubber particles as partial replacement for natural fine aggregate, is limited by its lack of strength. It is found that the addition of steel fibers is a solution to the limitation. This study proposes using porcelain waste coarse aggregates and steel fibers to improve the cubic compressive strength and flexural strength of CRC and avoid the pollution caused by porcelain waste. Porcelain waste was incorporated at replacement percentages of 25%, 50% and 100% by volume. Steel fibers were incorporated at volume fractions of 1% and 1.25%. The cubic compressive strength and flexural strength of CRC, steel-fiber-reinforced CRC (SFRRC) and SFRRC with porcelain waste were then tested. The results obtained show that the strengths of CRC are greatly improved by the incorporation of steel fibers and 25% porcelain waste. With the increase in porcelain waste content, the strengths of SFRRC containing porcelain waste decrease. Scanning electron microscopy was then conducted and the findings show that the strengths decrease at high porcelain waste content due to the weak bond between the glaze of porcelain waste and the cement matrix. The fracture processes of three types of concrete under four-point bending were monitored by using acoustic emission (AE) technique. Based on the AE data, the parametric analyses, including cumulative hits analysis, b-value analysis and RA-AF analysis, were performed for three types of concrete and presented characteristics of damage evolution of them. This paper provides information about the mechanical properties and fracture process of a new type of green concrete that can be used in bending members of concrete structures.

Engineering properties and stability of high-performance mortar incorporating untreated and treated steel reducing slag aggregate

The purpose of this study was to investigate the effect of steel reducing slag aggregate (SRSA) on the mechanical and durability properties of high-performance mortar specimens. Two series of mortar specimens were produced for this study using treated and untreated SRSA. Each type of SRSA was used as a partial-to-complete replacement for natural fine aggregate at the following ratios: 25%, 50%, 75%, and 100%. The water-to-binder ratio (w/b) in all of the specimens was designed at 0.35. The mechanical properties and durability of the specimens were observed using slump flow, fresh unit weight, compressive strength, water absorption and porosity, ultrasonic pulse velocity (UPV), electrical surface resistivity (ESR), thermal conductivity (TC), sulfate attack resistance, and expansion rate. Scanning electron microscopy (SEM) was conducted for the microstructure analysis. The findings indicate that increasing the SRSA content is negatively correlated with mortar strength development and durability, with higher SRSA content reduced mortar compressive strength and durability performance comparing with reference mixture. However, most of the SRSA mortar mixtures exhibited good strength and excellent durability, with high UPV (≥3660 m/s) and ESR (≥20KΩ-cm) values. Notably, compared to the mortar specimens made using untreated SRSA, those made using treated SRSA exhibited better performance and better volume stability.