Strength and transport characteristics of volcanic pumice powder based high strength concrete

In this study, the potency of volcanic pumice powder (VPP) as a supplementary cementitious material at varied levels (0%, 10%, 20%, and 30%) in high strength concrete (HSC) was investigated for its pozzolanic reactivity as a basis for strength and durability enhancement. Workability, transport properties and mechanical properties were tested in addition to the characterization of the products. X-ray florescence and strength activity index established the VPP oxides (SiO2 + Al2O3 + Fe2O3 = 76.01%) and pozzolanicity while diffraction techniques revealed the presence of anorthite (Al2CaO8Si2), and clinopyroxene (AlCaMgSiO6). Despite the paucity of calcium oxide and the excess of silica and alumina in VPP in contrast to OPC, yet it contributes significantly to the microstructural density and tortuosity of HSC pores thereby improving the strengths and transport properties as evidenced in the reduction of rapid chloride ions penetration (RCPT), and low initial surface (water) absorption (ISA) values. The maximum 180-day tensile, flexural and compressive strengths of the HSC-VPP sample were 6.22, 10.5 and 78.9 MPa, respectively. (C) 2019 Published by Elsevier Ltd.