Recycled concrete aggregate (RCA) produced from concrete waste has recently been a good alternative to natural aggregate because of the increased focus on sustainable development and environmental benefits. However, concrete incorporating RCA has inferior properties when compared to natural aggregate concrete. The inferior properties of RCA concrete can be improved by incorporating supplementary cementitious materials (SCMs). Fly ash and silica fume are commonly used SCMs in the concrete industry which improve the mechanical properties and durability of concrete. Nevertheless, there is an imminent deficiency of material in certain parts of the world, and finding a replacement is a challenge for the future of the concrete industry. Rice husk ash (RHA) is a waste material that can be used as a partial replacement to improve the inferior property of RCA concrete. In this study, mechanical properties such as compressive strength and splitting tensile strength are studied. Durability properties such as water absorption, chloride diffusion and acid attack were also investigated. Furthermore, fibrous and non-fibrous concrete were made to study the effect of RHA and RCA. The results revealed that RHA can be used to mitigate the poor performance of RCA concrete and improve the bond between concrete and fibers.

Sure, let's break down the response step by step:

1. Introduction to RCA and its Benefits:

   • Recycled concrete aggregate (RCA) is produced from concrete waste.
   • It is considered a good alternative to natural aggregate due to its sustainable and environmental benefits.

2. Challenges with RCA Concrete:

   • Concrete incorporating RCA has inferior properties compared to natural aggregate concrete.

3. Improvement with SCMs:

   • The inferior properties of RCA concrete can be improved by incorporating supplementary cementitious materials (SCMs).
   • Common SCMs include fly ash and silica fume, which enhance the mechanical properties and durability of concrete.

4. Material Deficiency and Alternative Solutions:

   • There is a shortage of SCMs in certain parts of the world.
   • Finding replacements for these materials is crucial for the future of the concrete industry.

5. Introduction of Rice Husk Ash (RHA):

   • Rice husk ash (RHA) is a waste material that can be used as a partial replacement to improve the properties of RCA concrete.

6. Study Focus:

   • The study focuses on mechanical properties such as compressive strength and splitting tensile strength.
   • It also investigates durability properties like water absorption, chloride diffusion, and acid attack.

7. Fibrous and Non-Fibrous Concrete:

   • Both fibrous and non-fibrous concrete were made to study the effect of RHA and RCA.

8. Results:

   • The results revealed that RHA can mitigate the poor performance of RCA concrete.
   • RHA also improves the bond between concrete and fibers.

By following these steps, we can understand the study's approach and findings regarding the use of RHA to enhance RCA concrete.