Evaluating the Influence of Palm Kernel Shell Ash on Ire Clay Geopolymer Concrete Cured at Ambient Temperature

Abstract

There is an abundance of clay deposit in Ire Ekiti which can serve as geopolymer source material and Palm kernel shell exists as a massive agro waste in South Western Nigeria. This study evaluates the effect of palm kernel shell ash (PKSA) as an additive on the compressive strength of Ire clay geopolymer concrete. The objective of the study is to determine the selected properties of the obtained concrete at room temperature. Palm kernel shell was burned at 650oC for 2 hours in a furnace. Natural clay collected from Ire Ekiti was manually pulverized, air dried and calcined in a furnace at 750o for 2 hours.  The geopolymer concrete was prepared at a mixing ratio of 1:2:3. The material constituents were calcined clay (source material), 12M of NaOH and Na2SiO3 (ratio of NaOH to Na2SiO3 was 2:5), river sand and 12.5mm granite were the fine and coarse aggregates respectively while PKSA of 0%,7.5% and 15% of the calcined  Ire Clay content were used as additive in preparing the geopolymer concrete. geopolymer concrete specimens were cured at ambient temperature till testing at different maturity ages of 7, 14 and 28 days. It was generally observed that increasing the percentage of PKSA as additive strongly improved the compressive strength gain with maturity of the Ire clay geopolymer concrete. At 28 days maturity, 7.5% PKSA addition improved the compressive strength by 166% while 15% PKSA addition improved the strength by 181% increase. The highest compressive strength was 7.67N/mm2 at 15% PKSA addition on 28 day. Conclusively, Ire clay and PKSA are viable source material and additive respectively for geopolymer concrete production. The Ire clay geopolymer concrete can be practically applied like conventional concrete in structural work especially in a rural community like Ire Ekiti where cement needs to be transported over kilometers. Also, the concrete performing well at ambient temperature makes it cost effective compare to most geopolymers that require heating at high temperature. It is recommended that further study on the durability should be done.