Durability properties of alkali pozzolan cement (APC)

This paper compares the durability properties of alkali pozzolan cement (APC) with high volume fly ash (HVFA) cement and ordinary Portland cement (OPC). The susceptibility to durability issues was investigated through the water absorption test using 28-day-old samples. Durability against chemical attacks was investigated through sulphuric acid attack, chloride ion penetration and carbonation tests on 1-year-old samples. The results indicated that APC occupies a median position in relation to OPC and HVFA, having greater resistance than HVFA for water absorption and carbonation, and greater resistance than OPC for sulphuric acid attack and chloride ion penetration. Chemical and microstructural reasons for the above behaviours are presented. A key index of durability performance is the free calcium hydroxide available and/or generated during cement hydration and durability exposure.