Evaluation of natural pozzolan for use as supplementary cementitious material

This paper presents preliminary study results on the use of local natural pozzolan (NP) as a mineral addition. The natural pozzolan was obtained from a source in north-western Algeria and was composed of zeolite and plagioclase, which are mineralogical materials containing large quantities of SiO2 and Al2O3. A number of cements were prepared in which portland cement (OPC) was replaced by NP in the range of 0-25%. The parameters investigated included pozzolanic activity, setting times, heat of hydration, compressive strength, and the crystalline hydration products (by XRD). The pozzolanic activity index was evaluated on the basis of physical and mechanical parameters (standards ASTM C618 and ASTM C311) and through a chemical analysis (European standard NF EN 196-5). The performance of natural pozzolan cement exposed to aggressive solutions (sulphuric and nitric acids) and their resistance to chloride permeability were also analysed.