Recycled Coarse Aggregate Research Articles

Study on Crack Resistance and Calculation Model of RAC Beams Strengthened with Prestressed CFRP

With the development of recycled aggregate concrete (RAC), the recovery rate of construction waste is improved, and the pollution problem is alleviated. In particular, RAC beams strengthened with prestressed carbon fiber reinforced plastics (CFRP) can exhibit improved mechanical properties, expanding RAC application. Four groups of reinforced RAC beam specimens contained 0%, 40%, 70%, and 100% recycled coarse aggregate, respectively. Each group of beams was first pre-cracked and then strengthened by prestressed CFRP with one layer and two layers respectively. Finally, the bearing capacity tests were performed for these beams. The test results show that as the recycled coarse aggregate content increases, the cracking moment and ultimate load capacity of the beam decrease, while its crack width increases. As the CFRP layer increases, the deformation and crack width of the beam decreases, while the number of cracks increases. The prestressed CFRP also exhibited tensile and peeling failure. A beam deflection calculation model was established by introducing a coefficient k representing the interaction between recycled aggregate and CFRP. The influence coefficient of concrete elongation on the crack width and average crack spacing of the beam was modified, and the crack width analysis model of the beam was established. The calculated results are in good agreement with the experimental observations. It can provide reference for the application and design of recycled concrete beams strengthened with prestressed CFRP.

Effect of Recycled Coarse Aggregates (RCA) on Geo-Polymer-Based Concrete

The construction industries are looking towards the production of environmentally friendly concrete, with the use of fewer natural resources, less energy, and minimum carbon dioxide emissions. For this reason, the geo-polymer concrete is one of the best options. The concrete produced with a polymerization process; a reaction between alkaline compounds containing alumina and silica; is called geo-polymer-based concrete. This study is focused on investigating the density and strength properties of geo-polymer concrete with Recycled Coarse Aggregates (RCA). Three mixes were designed with 0%, 50%, and 100% RCA with a fixed water-binder ratio equal to 0.4. The results revealed that the compressive, tensile, and flexural strength of geo-polymer-based concrete with RCA reduced and depended on the percentage of RCA used. The flexural performance of the concrete was observed better compared to compressive and tensile strength. However, the density of concrete is decreased by approximately 14% with the addition of RCA resulting in lighter concrete than the control mix.

Mechanical characterization of fiber-reinforced rubberized recycled concrete

Dumping non-biodegradable wastes, such as construction and demolition waste (CDW) and scrap tires, is causing significant environmental problems. Thus, this study used recycled coarse aggregate (RCA) and crumb rubber (CR) procured from CDW and scrap tires as a partial replacement of natural aggregates. 30% natural coarse aggregate (NCA) was replaced by RCA, and 0, 5, 10 and 15% natural fine aggregate (NFA) was replaced by CR. Besides these, 0.5% polypropylene (PP) fiber was incorporated into the concrete mixtures. Different physical and mechanical properties of rubberized recycled concrete (R2C) and fiber-reinforced rubberized recycled concrete (FR2C) were investigated. Microstructural analysis, chemical analysis, failure modes, and cost-effectiveness were also evaluated. Simplified regression equations have been proposed to predict various mechanical properties of R2C and FR2C mixtures. The inclusion of RCA, CR, and fiber decreased the slump value of the fresh concrete up to 69.7%. The compressive strength decreased with an increase in CR percentage, but it increased by including fiber content. Though all the R2C and FR2C specimens exhibited lower tensile and flexural strength, a marginal reduction was found in FR2C specimens containing up to 5% CR content, which was only 3.3% and 6.8% lesser compared to the control samples. The surface resistivity test revealed that the chloride ion penetrability may be very low for all the combinations of R2C and FR2C specimens. By raising the percentage of CR, the UPV decreased, but the addition of PP fiber slightly increased the value. The cost analysis results pointed out that both the R2C and FR2C combinations saved more energy (up to 2.22 times) and decreased fuel consumption (up to 20.2%). Finally, the present study will aid in advancing sustainable fiber-reinforced rubberized recycled concrete.

Experimental Study on Self-compacting and Self-healing Concrete with Recycled Coarse Aggregates

Experimental Study on Self-compacting and Self-healing Concrete with Recycled Coarse Aggregates

Mechanical properties of eco-friendly self-compacting concrete made from partially replaced single-use waste plastic and complete recycled coarse aggregate using RSM and ANN methods

The paper aims to use most of the recycled material from the waste and develop a sustainable Eco-Friendly Self-Compacting Concrete (EF-SCC). Two different plastic wastes, High-Density Polyethylene (HDPE) and Polypropylene (PP), were collected from the dumping yard, thoroughly cleaned, and shredded into the desired shape and size. The plastic was substituted with fine aggregate (FA) in amounts ranging from 5% to 20%, with a 5% rise in each mix. The recycled coarse aggregate was obtained by breaking the concrete cubes, beams, and cylinders available for testing at the concrete technology lab. Totally 4 mixes were prepared for M40 grade EF-SCC to determine the mechanical property at 4 different ages (7, 14, 28 and 56 days). The compressive strength results were then predicted using statistical tools such as RSM and ANN. It is observed that both HDPE and PP have workability in the range of 650mm to 800mm, which is acceptable according to EFNARC 2002. The RSM method yielded 99.69% for PP material, while HDPE had 98.17%. The optimum compressive strength values were achieved at 7.5% of HDPE and 5% of PP material at 28 days and 60 days of curing. The training, validation, Test, and All values of R for M40 grade concrete for HDPE and PP material were 0.9955, 0.9980, 0.9244, 0.9241, and 1, 0.972, 0.802, 0.972 respectively. The flexural strength of EF-SCC showed the best results at 15% replacement. The prediction of actual compressive strength with RSM was more accurate for HDPE material compared to ANN. Recycled aggregate showed positive signs in using waste material in construction industries.

The durability of spray steel fiber-reinforced recycled coarse aggregate concrete

To boost the application scope of coarse recycled aggregates (RA) with particle size in the range of 5–10 mm, a spray steel fiber reinforced coarse aggregate concrete (SSFRCAC) is developed, and the impact of cube compressive strength, RA replacement ratio, and steel fiber (SF) volume fraction on the durability of SSFRCAC is comprehensively examined through carbonization, sulfate attack, penetration, and freeze-thaw cycle tests. The anti-carbonation test results reveal that as the RA replacement ratio increases, the carbonation resistance of SSFRCAC decreases. The best anti-carbonation performance is achieved when the SF volume fraction is 1%. Additionally, a formula for calculating the carbonation depth is established. Based on the experimental data, the dynamic elastic modulus is recommended as the measurement standard for the freeze-thaw resistance cycle test. The sulfate resistance test results indicate that as the RA replacement ratio increases, the Sulfate Resistance coefficient also increases. SF block the thermal cracks of specimens and corrosion products as well as the formation of expansion cracks, so the corrosion resistance coefficient gradually tends to a certain stable level. According to the anti-permeability test results, the increase in the RA replacement ratio can suppress the anti-permeability performance. When the SF volume fraction is 1%, the concrete has the highest density and the best anti-permeability performance. Overall, the durability of SSFRCAC is found to be much better than that of general recycled SF Recycle aggregates concrete, which makes it more suitable for practical engineering applications.

Research on Quality Grading Evaluation and Performance Prediction of Construction Waste Recycled Materials

The application of construction waste in road engineering is an effective means to improve the level of resource recycling. Due to the lack of specialized sorting equipment for different types of construction waste and the high cost of manual sorting, resource utilization enterprises mainly rely on mixed crushing and regeneration in production, while there is a lack of systematic research on the application technical indicators of recycled aggregates for brick concrete mixed construction waste. This article proposes a quality evaluation model for construction waste coarse aggregates based on the theory of matter element extension, providing new ideas for quantitative evaluation of the quality status of coarse aggregates, and also providing reference for the rational selection of recycled coarse aggregates and the determination of mechanical parameters of coarse aggregates in the construction process, which is conducive to the evaluation and analysis of the quality status of recycled coarse aggregates.

Effects of bacterial consortium enhanced recycled coarse aggregates on self‐healing concrete immobilized with Bacillus megaterium MTCC 1684 and Bacillus subtilis NCIM 2193

AbstractThe strength and durability properties of the recycled aggregate concrete (RAC) have been affected by the cracks and the weak interfacial transition zone (ITZ) of the recycled coarse aggregates (RCA). However, the mechanical and physical features of RCA can be improved by microbially induced calcite precipitation (MICP). Therefore, immobilization techniques were used to protect and maintain the high efficiency of Bacillus bacteria for the formation and precipitation of calcium carbonates in self‐healing concrete over a period of time. The objective of the present study was to show the viability of the immobilized bacterial consortium‐enhanced RCA to form self‐healing cracks. Further, the self‐healing capability of enhanced RCA was investigated along with two other immobilization methods, that is, RCA and hydrated lime and brick powder (HBr)‐immobilized bacteria. The experimental results show that the increase in the bio‐deposition time improved the physical and mechanical properties of the RCA. Further, subsequently 56 days of the healing incubation period, the immobilized consortium‐enhanced RCA concrete specimens completely healed the cracks of width 0.58 mm. However, the equivalent cracks of width 0.56 mm were also recovered by the HBr immobilized bacterial cultures. Furthermore, the field emission scanning electron microscope (FESEM), energy dispersive spectroscopy (EDS) and X‐ray diffraction (XRD) analysis revealed that the existence of precipitation at the crack surface was calcium carbonate with a regular cubic‐shaped and lamellar layer morphology. The outcomes of the current study show that consortium‐enhanced RCA has promising potential to develop self‐healing concrete with self‐repaired and improved durability properties in the concrete construction field.

Porous Asphalt Mix Design Pavement by Incorporating a Precise Proportion of Recycled Coarse Aggregate

Porous Asphalt Mix Design Pavement by Incorporating a Precise Proportion of Recycled Coarse Aggregate

Assessing the compressive and splitting tensile strength of self-compacting recycled coarse aggregate concrete using machine learning and statistical techniques

The construction industry is adopting high-performance materials due to technological and environmental advances. Researchers worldwide are studying the use of recycled coarse aggregates (RCA) as a partial alternative to natural coarse aggregates in concrete due to their sustainability and environmental benefits. This study compares the predictive abilities of three different machine learning techniques in evaluating the mechanical properties of 28-day-old self-compacting concrete (SCC) incorporating RCA to better understand how design parameters affect the mechanical properties of SCC containing RCA. The study used a range of statistical methodologies and machine learning algorithms, such as ANN, SVM, and M5P trees, to examine the relationship between design elements and accurately forecast the mechanical characteristics of concrete. The ANN model exhibited notable superiority in effectively forecasting compressive strength (CS) and splitting tensile strength (STS) compared to other models, with uncertainty bands of 15.038%− 21.154% for CS and 15.701%− 19.008% for STS. Moreover, all the uncertainties were under the threshold of 35%. Notably, the water-cement ratio emerged as the most crucial parameter in accurately predicting the mechanical properties of SCC. Finally, the parametric evaluation conducted revealed that CS and STS are inversely proportional to water-cement ratio and aggregate-cement ratio, whereas, are directly proportional to the water-binder ratio, and water-solids percentage.

Efficiency and Mechanism of Surface Reinforcement for Recycled Coarse Aggregates via Magnesium Phosphate Cement.

Recycled aggregate concrete (RAC) exhibits inferior mechanical and durability properties owing to the deterioration of the recycled coarse aggregate (RCA) surface quality. To improve the surface properties of RCA, the reinforcement efficiency of RAC, and the maneuverability of the surface treatment method, this study used magnesium phosphate cement (MPC), a clinker-free low-carbon cement with excellent bonding properties, to precoat RCA under three-day pre-conditioning. Moreover, variable amounts of fly ash (FA) or granulated blast furnace slag (GBFS) were utilized to partly substitute MPC to enhance the compressive strength and chloride ion penetration resistance. Subsequently, FA-MPC and GBFS-MPC hybrid slurries with the best comprehensive performance were selected to coat the RCA for optimal reinforcement. The crushing value and water absorption of RCA, as well as the mechanical strengths and durability of RAC, were investigated, and microstructures around interfaces were studied via BSE-EDS and microhardness analysis to reveal the strengthening mechanism. The results indicated that the comprehensive property of strengthening paste was enhanced significantly through substituting MPC with 10% FA or GBFS. Surface coating resulted in a maximum reduction of 8.15% in the crushing value, while the water absorption barely changed. In addition, modified RAC outperformed untreated RAC regarding compressive strength, splitting tensile strength, and chloride ion penetration resistance with maximum optimization efficiencies of 31.58%, 49.75%, and 43.11%, respectively. It was also evidenced that the improved MPC paste properties enhanced the performance of modified RAC. Microanalysis revealed that MPC pastes exhibited an excellent bond with RCA or new mortar, and the newly formed interfacial transition zone between MPC and the fresh mortar exhibited a dense microstructure and outstanding micro-mechanical properties supported with an increase in the average microhardness value of 30.2-33.4%. Therefore, MPC pastes incorporating an appropriate mineral admixture have enormous potential to be utilized as effective RCA surface treatment materials and improve the operability of RCA application in practice.

Utilization of recycled coarse aggregate and high volume of GGBS in self-compacting concrete – an experimental study

Purpose The purpose of this study is to investigate the behaviour of M40 grade of self-compacting concrete (SCC) with high volume of ground granulated blast furnace slag (GGBS) (50%) and recycled concrete aggregate (RCA) content up to 100% to assess the mechanical properties of SCC. As per guidelines of IS: 383 – 2016, the RCA can be replaced up to 20% of natural coarse aggregate up to M25 grade of concrete. This study assesses the mechanical properties of SCC beyond 20% of RCA content. Based on the experimental investigations, the compressive strength of mixes decreases as the content of RCA increases. It is found that concrete mixes with 20% RCA and shows the maximum compressive strength at 56 days. Design/methodology/approach The fresh properties as per EFNARC and IS: 10262–2019 guidelines, ultrasonic pulse velocity testing, mechanical properties and microstructure analysis have been conducted to evaluate the performance of SCC with RCA for practical applications. Findings From the experimental investigations, it is found that up to 50% of recycled coarse aggregate can be used for structural applications. Originality/value The environmental pollution and dumping of waste on green land can be reduced by effective utilization of recycled coarse aggregate and GGBS in the production of SCC.

EXPERIMENTAL STUDY ON BEHAVIOR OF RECYCLED AGGREGATE IN CONCRETE

Concrete is one of the most widely used construction material in the world. Increase in population growth is leading to increase in various demands like cultivation, transportation, construction etc. Nowadays, there is a tremendous increase in the demand for construction works like residential buildings, bridges, dams, roads etc. and because of this increase in demand the availability of sources for concrete ingredients is getting difficult. Hence people are looking for alternative sources for the concrete ingredients in order to full fill their requirements. This dissertation work deals with the study of strength of concrete incorporating Recycled Aggregate concrete(R.A.C).The main objective of this investigation is to find out up to what percentage the Natural Coarse Aggregate(N.C.A) can be replaced by recycled coarse aggregate(R.C.A) in the concrete mix and to find out the extra quantity of cement to be added for each percentage replacement byR.C.A. to achieve its target mean strength. In this ongoing project work it is concentrated only on the use of R.C.A. A series of tests were carried out to determine the compressive strength, split tensile strength, flexural strength with and without recycled aggregates. Natural coarse aggregates in concrete were replaced with 0%, 20%, 40%, 60%, 80% and 100% of crushed concrete coarse aggregates. For the strength characteristics, the result showed a gradual decrease in compressive strength, split tensile strength, flexural strength and modulus of elasticity as the percentage of recycled aggregate is increased. Key Words: Natural Coarse Aggregate, Recycled coarse aggregate, compressive strength, split tensile strength, flexural strength.

Experimental and numerical evaluations of the shear performance of recycled aggregate RC beams strengthened using CFRP sheets

Conserving the ecosystems of the globe, protecting natural resources, and improving environmental conditions can all be achieved by considering sustainability in the construction industry. Recycling of building and demolition waste is one of the key approaches being investigated to accomplish this target. Twelve reinforced concrete (RC) beams were constructed for the current study in order to analyze the shear behavior of recycled aggregate concrete (RAC) beams externally strengthened with carbon fiber reinforced polymer (CFRP) sheets. The main goal of the experimental matrix was to investigate the effect of the recycled aggregate ratio on the shear response of RAC, where three recycled coarse aggregate ratios of 20%, 60%, and 100% were suggested. Additionally, the effects of incorporating two or four CFRP strengthening layers on the ultimate load, failure pattern, load-deflection responses, and stiffness of RAC beams were also investigated. Results revealed that, when different ratios of recycled aggregate estimated at 20%, 60%, and 100% were substituted for natural aggregates, the compressive strength decreased by 4.3%, 24.2%, and 40.0%, respectively, compared to natural aggregate concrete. Moreover, the RC beam that was cast utilizing 20% recycled aggregates and strengthened with four CFRP sheets exhibited the highest ultimate load among all the tested RAC beams of 84.8 kN, which was 22.9% higher than the un-strengthened specimen totally cast with natural aggregate. Furthermore, a three-dimensional (3D) non-linear finite element model (FEM) was constructed using the ABAQUS program in order to compare the effects of employing continuous CFRP sheets for the whole critical shear span length to intermittent strips that had been experimentally tested.

Strength and durability properties of concrete made with recycled coarse aggregate and seashore sand

The process of depletion of sources of natural aggregates poses challenges to produce technically and environmentally suitable concrete. Aggregate compositions found in construction and demolition (C&D) waste offer potential alternatives to natural coarse aggregates. Additionally, the utilization of abundantly available natural material like seashore sand, as a replacement for river sand, can present a viable solution to this problem. This research paper investigates the performance of concrete that incorporates 40% recycled coarse aggregates, along with varying percentages of seashore sand as replacements for river sand (0%, 10%, 20%, 30%, 40%, 50%, and 100%). The evaluation focuses on strength properties, including compressive strength tests on cylinders and impact resistance tests, as well as durability properties such as water penetration tests under pressure and sulphate attack tests. The experimental results indicate that concrete incorporating both recycled coarse aggregates and seashore sand replacements yields favorable outcomes in terms of strength and durability when compared to the controlled concrete, particularly at suitable replacement proportions.

Environmental compatibility of pervious concrete with recycled coarse aggregate applying in riparian buffer area

Knowledge of the environmental compatibility of pervious concrete with recycled coarse aggregate (RA) is significant, especially when used in riparian buffer areas. In this study, investigations on the growth performance of two grass combinations (I: Festuca and Ryegrass; II: Cosmos bipinnata, Festuca and Ryegrass) and water purification capacity of the pervious concrete with the RA were carried out to evaluate the environmental compatibility; the former was performed by measuring the maximum height and germination rate during 28 days of growth; the latter was measured using a water immersion test with measurements of the nutrient content (NO3--N, NO2--N, NH4+-N, T-N, PO43--P, and T-P) and organic matter (COD and DOC) at certain intervals. Prior to that, the effects of RA grading (5–15 mm, 15–20 mm, 20–25 mm) and water-cement ratio (W/C) (0.4, 0.45, 0.5) on strength and porosity were determined, along with suitable concrete being selected for the test of environmental compatibility. The results showed that a maximum RA grading of 20–15 mm was the best for plant growth, manifesting the greatest maximum height of 9.8 cm and germination rate of 42.42%. Pervious concrete with vegetation can efficiently purify the surrounding water, with a removal efficiency of more than 98% for NH4+-N, T-P, PO43--P, and COD. The removal efficiency increased over time, except for the DOC. W/C had no distinct effect on plant growth and matter removal, except for NO2--N and NO3--N, which increased as W/C increased. This paper highlights the environmental technical merits of pervious concrete with RA and provides technical support for using the material in riparian buffers.

A Study on Sustainable Concrete by using Recycled Concrete Aggregate and Waste Glass

Sustainable and affordable building materials are a developing concern in the construction sector. This abstract outline a creative method for creating a cost-effective concrete mix that uses discarded glass as the fine aggregate and recycled coarse aggregate (RCA) as the main coarse material. The goal is to investigate whether using recycled materials instead of traditional aggregates is feasible while both addressing environmental issues and lowering construction costs. The proposed concrete mix's mechanical qualities, financial ramifications, and environmental impact were all compared through laboratory experiments, a thorough assessment of the literature, and comparative analysis. The scrap glass came from glass bottles and other abandoned containers, while the RCA came from crushed concrete waste. The experimental studies assessed different concrete mix proportions while taking into account various replacement amounts for RCA and waste glass. Along with other crucial qualities like workability, density, and durability, the mechanical properties including compressive strength, tensile strength, and flexural strength were evaluated. The test outcomes were contrasted with a control concrete mixture made up only of common aggregates. The results of the research show that using waste glass as fine aggregate and recycled coarse material in the making of concrete can substantially reduce building costs. The mechanical performance of the concrete was not significantly affected by the use of the RCA and waste glass in place of normal aggregates. Additionally, using these recycled materials lowers the amount of waste that is transported to landfills and helps conserve natural resources. Economic concrete mixtures that use waste glass as fine aggregate and recycled coarse material have enormous potential for green building techniques. This method is appealing for large-scale construction projects due to the lower material cost and positive environmental effects. To make sure the best mix proportions are employed, it is necessary to take the specific application into account as well as the engineering requirements. This study supports continuing initiatives to advance affordability and sustainability in the building sector. As well as studying further strategies to improve the engineering features of recycled aggregate-based concrete, future research could concentrate on examining the long-term performance and durability of the suggested concrete mix.

Enhancing concrete performance: Surface modification of recycled coarse aggregates for sustainable construction

In this study, the researchers introduce an innovative method to enhance the utilization of recycled coarse aggregates (RCA) derived from construction and demolition waste (C&D) in sustainable concrete production. The presence of old cements mortar on the surface of these aggregates poses a challenge to their mechanical properties. To tackle this issue, the researchers propose a unique approach that combines chemical treatment and abrasion techniques. Firstly, RCA is immersed in a 0.5 mol hydrochloric acid (HCl) solution, weakening the adhering mortar. Subsequently, abrasion treatment removes the weakened mortar from the RCA surface. The study explores the incorporation of these surface-modified RCAs at varying levels, from 0% to 100% in 25% increments. Various concrete properties, including workability, compressive strength, flexural strength, split tensile strength, and microstructural characteristics (XRD, SEM, and EDAX), along with modulus of elasticity, are assessed. Results indicate that the combination of these modification techniques significantly enhances RCA properties. At the 100% replacement level, surface-modified RCA results in a reduction of compressive, flexural, and split tensile strength by 08.31%, 10.61%, and 07.90%, respectively, in comparison to the reference concrete. Likewise, the modulus of elasticity decreases to 30.82, and porosity decreases to 27.82% at the same replacement level. However, SEM analysis illustrates improved bonding between RCA and cement matrix due to surface modifications, leading to reduced porosity and the formation of dense Interfacial Transition Zones (ITZs). Cost analysis reveals that recycled aggregate concrete (RAC) mixtures can be more economical than those utilizing natural aggregates (NA). In summary, this novel surface modification technique presents a promising avenue for optimizing RCA utilization in sustainable concrete production, promoting environmental conservation, and efficient waste management in the construction sector.

Effects of Manufactured Sand and Steam-Curing Temperature on the Compressive Strength of Recycled Concrete with Different Water/Binder Ratios.

New building materials (manufactured sand and recycled coarse aggregates) can conserve raw materials and protect the environment. Prefabricated members can shorten the construction time of a structure. To use manufactured sand and recycled coarse aggregate in the preparation of precast member concrete, an economical and practical steam-curing scheme must be developed such that the compressive strength of precast manufactured sand recycled concrete (MRC) meets the requirements for hoisting. The effects of different steam-curing temperatures (standard curing, 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C) on the compressive strength of MRC with three water/binder ratios (W/B) (0.46, 0.42, and 0.38) were studied. In addition, the microstructure of MRC was examined using a scanning electron microscope. The equivalent age-compressive strength model was used to estimate the recycled concrete with manufactured sand. The results showed that the strength of MRC with a water-cement ratio of 0.46, 0.42, and 0.38 reached 33.9, 38.7, and 45.1 MPa, respectively, after 28 days of standard curing. The results also indicated that an increase in the steam-curing temperature had a positive effect on the early compressive strength of MRC and a negative effect on the 28 d compressive strength. This behavior was more obvious for MRC with a low W/B ratio. For MRC with a W/B of 0.46, 0.42, and 0.38, after steam-curing for 6 h, the compressive strength reached 32-65%, 36-70%, and 40-77% of the design strength, respectively. The optimum steam-curing temperatures for MRC with W/B of 0.46, 0.42, and 0.38 were 60 °C, 60 °C, and 50 °C. A decrease in W/B has a negative impact on the accuracy of MRC estimation using the equivalent age-compressive strength model. The maximum deviation of the prediction was within 10%, and the accuracy of the model was acceptable. This study provides a useful reference for the production of prefabricated MRC components in factories and subsequent construction.

Effect of recycled coarse aggregate treated with recycled binder paste coating and accelerated carbonation on mechanical and physical properties of concrete

Construction and demolition waste (CDW) is a viable source of recycled aggregates for the production of concrete. However, recycled concrete aggregate (RCA) usually has inferior properties compared to natural aggregates (NA) mainly due to the mortar bonded to its surface, which directly affects the mechanical and physical properties of concrete. Therefore, in this work it is proposed to strengthen the bonded mortar of low-quality coarse recycled aggregate (CRA) through a combined treatment of coating with a slurry of recycled binder paste (RBP) and accelerated carbonation. Mechanical and physical tests were carried out for concretes with replacements of 50% and 100% CRA and the results obtained were compared with a control series. The results showed an effective improvement in the mechanical and physical properties of the concretes with treated recycled aggregate, achieving in some cases values close to those of the control, even considering the high replacement percentages.