Properties of Pastes, Mortars and Concretes Containing Natural Pozzolan

Journal Article
J., Shannag, M. . 1995
Publication Work Type: 
Research, Cement and Concrete Research
Issue Number: 
Volume Number: 
Publication Abstract: 

Laboratory tests were conducted to investigate the effects of a local natural pozzolan on certain paste, mortar and concrete properties when used as a separate admixture or interground in amounts more than used in the commercial pozzolanic Portland cement (i.e. more than 15% by weight). The pozzolan was ground in two levels of fineness and was used together with some local cements. According to the results the finer pozzolan was more active. It could be added upto 25% by weight of cement without reducing the 28 day strength. At 35% admixing levels the strength of ordinary Portland could be matched at around 90 days. Pozzolanic addition reduced the heat of hydration, somewhat prolonged the setting times and improved the soundness of cements. It caused some increase in mortar shrinkage and slightly reduced the workability of mortars and concretes. Based on the test results the use of the natural pozzolan as a separate concretre admixture and as an addition in the production of a family of blended local cements are recommended.