Concrete is one of the most widely used construction materials due to its high compressive strength, durability, versatility, and ability to withstand heavy structural loads. Conventional concrete is mainly composed of cement, fine and coarse aggregates, water, and reinforcing steel, with chemical or mineral admixtures used when required. However, the rapid growth of the construction industry has resulted in extensive consumption of natural resources and has generated large quantities of construction and demolition (C&D) waste. Therefore, the development of sustainable concrete using recycled and alternative materials has become increasingly important.

Recycled aggregates obtained from demolished concrete, brick masonry, construction sites, ready-mix concrete plants, and damaged structures can be used as partial substitutes for natural aggregates. Their utilization can reduce the extraction of natural resources and help minimize the environmental problems associated with construction waste disposal. Similarly, sugarcane bagasse is an important agricultural by-product generated during sugar production. After the extraction of sugarcane juice, a considerable quantity of bagasse remains, which can be processed and burned to produce bagasse ash. Due to its pozzolanic properties and silica content, bagasse ash has potential for use as a partial replacement for cement in concrete.

Silica fume is a highly reactive supplementary cementitious material obtained as a by-product of silicon and ferrosilicon alloy production. It contains a high proportion of very fine, non-crystalline silica particles. Because of its extremely small particle size and high reactivity, silica fume can improve the packing density, strength, impermeability, and durability of concrete. The combined use of recycled aggregates, bagasse ash, and silica fume can therefore provide an effective approach for producing sustainable and high-performance concrete while reducing the consumption of conventional raw materials.

The present study investigates the performance of M25-grade concrete by partially replacing natural coarse aggregates with recycled coarse aggregates and cement with bagasse ash and silica fume. Recycled coarse aggregates were used at replacement levels of 15%, 30%, and 45%, while bagasse ash and silica fume were incorporated at 5%, 10%, and 15% replacement levels. The prepared concrete mixes were evaluated to determine the effect of these materials on the performance of concrete and to identify an optimum combination.

Based on the experimental investigation, the modified concrete mixes demonstrated satisfactory and improved performance at suitable replacement levels. Among the different combinations studied, BRC2, containing 30% recycled coarse aggregates, 10% bagasse ash, and 10% silica fume, was identified as the optimum mix. The study concludes that the appropriate incorporation of these recycled and supplementary materials can reduce the dependence on natural aggregates and cement while promoting waste utilization and sustainable construction.

 

Keywords: High-Performance Concrete, Recycled Aggregates, Bagasse Ash, Silica Fume, M25 Concrete, Sustainable Construction, Waste Utilization.