Abstract

Materials with pozzolanic characteristics may be used to partially replace cement in mortars or concrete and are known to provide durability to the products. Cement functions by forming a plastic paste when mixed with water, which develops rigidity (sets) and steadily increases in compressive strength (hardness) by chemical reaction with the water (hydration). The use ofsupplementary cementitious materials (SCMs), such as groundnut shell ash as part of binders for concrete has been increasing throughout the world, particularly in the production of high-strength and high performance concrete. This study evaluated the feasibility of using Groundnut Shell Ash (GSA), a by-product groundnut shell, obtained under controlled calcination as a partial replacement for Portland cement in concretre. The ash was produced calcination temperatures of 500°C, 600°C and 700°C, and the pozzolans were labelled GSA500, GSA600 and GSA700 respectively and tests were conducted to characterize the physical-chemical parameters of the GSA and the pozzolanic activity. The compressive strengths of applying GSA500 had highest strength at 10 and 20% with 18.60 and 20.00 at 28days that progressed to 23.00 and 23.50MPa at age 35days of curing respectively. The compressive strengths of applying GSA600 had highest strength at 10 and 20% with 19.50 and 19.00 at 28days that progressed to 23.00 and 21.50MPa at age 35days of curing respectively. The compressive strengths of applying GSA700 had highest strength at 10, 20 and 30% with 22.00, 20.50 and 21.50 at 28days that progressed to 24.00, 22.50 and 21.50MPa at age 35days of curing respectively. The use ofGSA700 at 10% with 22.00MPa has the highest compressive strength at 28th day of curing, which showed the best applicable pozzolan in partial replacement of OPC .in concrete. Pozzolanic activity index (PAI) at 10, 20, 30 and 40% application has the highest values with GSA700, GSA700, GSA700 and GSA600 concretes which were 95.7, 89.1, 80.4 and 69.6% respectively. GSA700 has the highest value of PAI as 95.7%. majority of the concrete partially replaced by GSA have their PAI values above the range of 75% specified by ASTMC 618 (2019).The results showed the technical feasibility of using the GSA as a pozzolanic material in construction, which would provide an alternative to proper disposal for this waste while providing products with high technical performance.