Investigating the transport properties and durability properties of low clinker concrete

One of the several strategies proposed to address the needs of the high and increasing worldwide demand of cement and concrete while reducing CO2 emissions of the industry is reducing the clinker factor of cement using supplementary cementitious materials (SCMs). Among all SCMs, calcined clay and highly available natural pozzolans seem to have a high potential to replace clinker in Portland cement when combined with limestone. This is mainly due to low CO2 intensity, high availability, and good performance to meet the construction standards. In this thesis, the transport and durability properties of low-clinker concrete are investigated. The concrete specimens are made replacing up to 65% of clinker with blends of limestone and calcined clay or limestone and volcanic ash and cured for 28 days. The compressive strength results achieved at 28 days for samples with SCM exceeded the minimum concrete class (45 MPa) given in BS EN 206-1 by more than 20% and 35% for calcined clay and volcanic ash respectively. 55% clinker replacement with limestone and volcanic ash (VA) combined with Na2SO4 showed excellent resistance to chloride migration. The results from the study showed that blends of limestone with calcined clay or volcanic ash at 55% and 65% clinker replacement levels produces excellent durability performance in concrete and even better when compared to CEM III/A consisting of 50: 50 clinker to ground granulated blast-furnace slag (GGBS) ratio.