Influence of Volcanic Ash Calcination on the Compressive Strength of Volcanic ash Laterized Concrete

Abstract

This paper investigated the effect of volcanic ash (VA) calcination on the compressive strength of volcanic ash blended laterized concrete (VALC). The effect was studied using VA in VALC at two levels of treatment: natural and calcinated. Laterite and VA contents were varied between 0 - 30% in steps of 10% with a design mix for 28-day target strength of 25 MPa using the British Method. A total of ninety-six concrete cubes of 100 mm were tested after curing in water for 3, 7 and 28 days. Chemical analysis showed that SiO2 + Al2O3 + Fe2O3 content for natural and calcinated VA was 71 % and 74 % respectively which met the requirement of ASTM C618:2008 for pozzolanic materials. VALC cast with calcinated VA at 800 ºC for all replacement levels (10-30%) of cement with VA gave higher compressive strength than those cast with natural VA. The increases in the compressive strength of VALC were pronounced on days 3 and 7 than on the 28-day. However, increases in the contents of both VA and laterite in VALC reduced the compressive strength.