Influence of pumice and zeolite on compressive strength, transport properties and resistance to chloride penetration of high strength self-compacting concretes

Abstract

This paper investigates the effect of two different natural pozzolan (pumice and zeolite) on compressive strength (fc), transport properties and resistance to chloride penetration both in immersion and tidal conditions when used in high strength self-compacting concrete (HSSCC). First, the chemical and mineralogical composition as well as the microstructure and the pozzolanic activity of the natural pozzolan are studied. Then, two percentages, 10% and 15%, of pumice and zeolite instead of Portland cement in HSSCC are investigated. Five concrete mixtures with a control mixture without any pozzolan are prepared and tested in both fresh and hardened states. The results show that the studied zeolite is a clinoptilolite that presents higher pozzolan activity compared to pumice. However, the compressive strength of mixtures containing zeolite remains low compared to control mixture. On the contrary, mixtures with pumice present compressive strength values close or higher than the ones of the control mix at both early and long term ages with a remarkable increase at long term. For durability purposes, the transport properties of the different mixtures are studied through capillary absorption, water absorption, water penetration, electrical resistivity, chloride migration and diffusion tests. The results show that, both pumice and zeolite pozzolan are found to have a significant effect on the increase of the resistance to chloride penetration in both immersion and tidal conditions. However, zeolite mixtures exhibit better resistance. This research shows that, the substitution of Portland cement by 15% of pumice or 10% of zeolite in HSSCC is affordable in all aspects.