MECHANICAL PERFORMANCE AND WATER ABSORPTION CHARACTERISTICS OF CEMENT MORTARS INCORPORATING RECYCLED CONCRETE WASTE POWDER AS CEMENT PASTE REPLACEMENT
Kavitha V. 1, Jyothi T. K.2
1Assistant Professor, Government SKSJTI, Bengaluru – 562159, India
2Associate Professor, KR Pete Krishna Government Engineering College KR Pete, Bengaluru, India
Abstract: The rapid growth of construction and demolition (C&D) waste and the increasing environmental impact associated with cement production have intensified the need for sustainable alternatives in cement-based materials. This study investigates the feasibility of utilizing recycled concrete waste powder (RCWP) as a partial cement paste replacement in MM4 grade cement mortar. Mortar mixtures containing RCWP at replacement levels of 5–50% were prepared with water–cement ratios of 0.70, 0.80, and 0.90. The fresh and hardened properties of the mortars were evaluated through flow table, cone penetration, and compressive strength tests at curing ages of 7, 14, 28, 56, and 90 days. The influence of RCWP on durability was further examined through water absorption analysis. The experimental results showed that the incorporation of RCWP progressively reduced mortar workability because of its higher specific surface area and water absorption characteristics. Nevertheless, moderate replacement levels enhanced the mechanical performance of the mortar. The optimum performance was obtained at 15% RCWP replacement with a water–cement ratio of 0.70, achieving a 28-day compressive strength of 23.43 MPa, which further increased to 24.01 MPa after 90 days. Replacement levels exceeding 25% resulted in a gradual reduction in compressive strength owing to the cement dilution effect and increased pore connectivity. The overall trends indicate an inverse relationship between compressive strength and water absorption, highlighting the role of pore refinement in improving mortar performance. The findings demonstrate that recycled concrete waste powder can be effectively utilized as a sustainable cement paste replacement in masonry mortar at moderate replacement levels. The proposed optimum mix provides a balance between workability, mechanical performance, and durability while contributing to reduced cement consumption, effective utilization of construction waste, and the promotion of environmentally sustainable construction practices.
Keywords: Recycled concrete waste powder; Cement mortar; Cement paste replacement; Compressive strength; Workability; Sustainable construction.
VOLUME 10 ISSUE 06 2026: 403 – 422