Conservation of natural resources and rapid urbanization has prompted growing demand for natural Aggregate by construction industry. This demand is compounded by considerable decline in the availability of good quality natural Aggregate and enormous increase in the quantities of demolished Concrete. The alternative materials to cement in terms of fly ash and other pozzolanic materials were evolved, popular alternative material to coarse Aggregate are being explored. Recycled Aggregate is one such alternative and the present research work is a step forward in developing the design parameters using stress block parameters. The objective of present investigation is to develop stress - block parameters for the design of reinforced Recycled Aggregate Concrete members. To arrive at the objectives defined above, a comprehensive experimental programme was undertaken. The influence of replacement ratio, (Rr) the ratio of Recycled coarse Aggregate to total coarse Aggregate (Rr=RCA/TCA) on mechanical properties of Recycled Aggregate Concrete was studied. The scope of the investigation programme is defined to generate stress strain test data of Concrete, viz; M15, M20, M25, M30, and M35 and five replacement ratios, viz; 0, 0.5, 0.75, 0.85, and 1.0 were considered. A total of 150 cylinder specimens' were cast for the stressstrain characteristics of hardened Concrete.

Optimization and economization of processes and structures have been considered from time immemorial and many things have been done to achieve this goal. Protecting the environment and reducing the amount of waste material in nature is very important. Today, the problem of using Recycled materials resulting from the destruction of buildings and the reuse of these materials in the construction of Concrete has been considered. In this research, the shear behaviour of Concrete beams manufactured with Recycled coarse Aggregate was studied. 9 Concrete beams with a cross-section 150 mm wide and 200 mm high and a length of 1500 mm manufactured and tested. Recycled Aggregate from building demolition was used at 0%, 50% and 100% mass replacement of natural Aggregate. Specimens underwent a four-point bending test. In this test, the shear capacity, maximum deflection at the mid-span of the specimens and tension strain were measured. The determination of the shear behaviour of Recycled Aggregates Concrete beams according to transverse reinforcement spacing was the aim of this study. The results were also compared with ACI, CSA and Eurocode 2 requirements. According to the test results, it was found that there is a significant difference in the shear behaviour of Recycled and natural Aggregate Concrete beams

The transformation from a conventional consumption based society to a sustainable society is urgently required due to the pollution of the natural environment, the exhaustion of the natural resources and the decreasing capacity of the final waste disposal facilities. One of the ways to solve this problem is to use Building Demolished Waste (BDW) Concrete as Aggregates in structural Concrete. The Aggregates thus obtained can be called as Recycled Concrete Aggregate (RCA). Concrete is a versatile material with numerous applications, but the only problem with Concrete is its brittle behaviour more so in Recycled Aggregate Concrete. This brittleness in Concrete can be overcome by dispersing fibers discretely in the material of Concrete. In the present work, Glass Fiber Reinforced Recycled Aggregate Concrete (GFRRAC) was developed. The mechanical properties of GFRAC with M20 & M40 grade Concretes, for different replacements of Recycled Concrete Aggregate (RCA) in Natural Aggregate (NA) are presented. It was observed that there was 10-17% increase in split tensile strength and about 10-14% improvement in flexural strength with fiber addition in Recycled Aggregate Concrete. There is an improvement in the modulus of elasticity of Concrete. The values of split, flexure and modulus of elasticity obtained were also compared with the Indian Standard Codal Provisions. The increased energy absorption capacity in GFRRAC indicates higher toughness and better post elastic deformations in the event of seismic actions.

This study examines liquid polyvinyl alcohol (PVA) impregnation of Recycled Concrete Aggregate (RCA) to refine pore structure and evaluate its influence on the fresh and hardened properties of companion Concretes, using natural Aggregate Concrete as the benchmark. Aggregates were pretreated at progressively higher PVA dosages and characterized for specific gravity, water absorption, and gradation, and Concretes with untreated and PVA-treated RCA were assessed for slump, water absorption, compressive strength, and drying shrinkage. The investigation was intentionally designed for non-structural Concrete applications such as paving blocks, curbs, and lightweight elements, where durability and sustainability are prioritized over high strength. Results indicated that increasing PVA dosage enhanced Aggregate density and reduced water absorption at higher levels (10%), but also caused trade-offs in workability and mechanical strength. Workability improved at 6% PVA but declined at higher contents, while compressive strength decreased at 6–8% and partially recovered at 10%. Drying shrinkage increased slightly with PVA addition. Overall, PVA pretreatment improved Aggregate densification and moisture resistance but required dosage optimization for practical use in durable, non-structural RCA Concretes aimed at sustainable resource utilization.

This research aimed to investigate the mechanical and physical properties of Roller Compacted Concrete (RCC) used with Recycled Concrete Aggregate (RCA) as a replacement for natural coarse Aggregate. The maximum dry density method was adopted to prepare RCC mixtures with 200 kg/m³,of cement content and coarse natural Aggregates in the Concrete mixture. Four RCC mixtures were produced from different RCA incorporation ratios (0%, 5%, 15%, and 30%). The compaction test, compressive strength, splitting tensile strength, flexural tensile strength, and modulus of elasticity, porosity, density, and water absorption tests were performed to analyze the mechanical and physical properties of the mixtures. One-way Analysis of Variance (ANOVA) was used to identify the influences of RCA on RCC’, s mechanical properties. As RCA increased in mixtures, some mechanical properties were observed to decrease, such as modulus of elasticity, but the same was not observed in the splitting tensile strength. All RCCs displayed compressive strength greater than 15. 0 MPa at 28 days, splitting tensile strength above 1. 9 MPa, flexural tensile strength above 2. 9 MPa, and modulus of elasticity above 19. 0 GPa. According to Brazilian standards, the RCA added to RCC could be used for base layers.

Recently, there has been an increasing trend toward the use of sustainable materials. Sustainability helps the environment by reducing the consumption of non-renewable natural resources. Concrete – the second most consumed material in the world after water – uses a significant amount of non-renewable resources. As a result, an experimental investigation was conducted to study the hardened properties of Concrete constructed with 20% and 50% Recycled Concrete Aggregate (RCA) (coarse) as well as 6% silica fume. This experimental program consisted of six mix designs. Experimental results showed that the compressive and tensile strength of Concrete improve by using Recycled Concrete Aggregate (RCA) (coarse) and silica fume in the mix design. For example, the compressive strength of Concrete containing 6% silica fume and 20% Recycled Concrete Aggregate at age of 56 days was 14% greater than reference Concrete mix, while with increasing percentage of recovered Concrete Aggregate by 50%, this parameter increased by only 4% which shows the inverse effect of increasing the amount of recovered Concrete Aggregate on compressive strength. The hardened properties of Concrete were compared with the provisions of the international design codes (U. S., Australia, Canada, Europe, and Japan) as well as a database of conventional Concrete. Results showed that the RCA has superior hardened properties compared with the reference Concrete mix.

In this research, the mechanical properties of Concrete in the conditions of using natural Aggregates and comparing the results with the replacement of Recycled Aggregates with values of 10, 20, 30 and 40% have been investigated. In the first part of the study, the results showed that the specific gravity of Concrete in the presence of 40% of Recycled sand and gravel was 1.02% and 2.38%, respectively. Also, in terms of compressive strength, the lowest decrease in compressive strength occurred in 10% of Recycled sand and the highest decrease in compressive strength occurred in 40% of Recycled sand. Then, the mechanical properties of ordinary Concrete with Concrete containing waste plastic (PET) were compared with 2, 4, 6, 8 and 10% of Concrete volume. In this regard, the results of the study indicate a decrease in compressive strength of Concrete compared to control Concrete. In this regard, the lowest reduction in compressive strength was 2.01% in the presence of 2% waste plastic (PET) and the highest reduction in compressive strength was 16.39% in the presence of 10% waste plastic (PET). Regarding flexural strength, the results showed an increase in flexural strength; So that the lowest increase in flexural strength of 6.27% occurred in the presence of 2% waste plastic (PET) and the highest increase in flexural strength of 39.49% occurred in the presence of 10% waste plastic (PET). In the end, the results showed that increasing the presence of waste plastic (PET) has led to a decrease in water absorption of samples. In this regard, the lowest decrease in water absorption by 5.26% and the highest decrease in water absorption by 23.08% occurred in the presence of 2 and 10% waste plastic (PET), respectively.