BEHAVIOR OF END-RESTRAINED SHRINKAGE CRACKS OF CEMENT MORTAR WITH DIFFERENT TYPES OF CEMENT

Abstract

The aim of study is to understand the behavior of shrinkage cracks of cement mortar, using different types of cement (O.P.C), (S.R.P.C) & (W.P.C) with mix proportion (1:2.5) cement: sand by weight, and water /cement ratio (0.5) for all series. The samples were cast in (I) shape steel moulds and had lateral restraint to resist volume changes (shrinkage & creep) in cement mortar under wetting and drying cycles (moisture content changes), the study consisted also determining compressive strength and modulus of rapture for the cement mortar. Experimental results showed that compressive strength of mortar of ( O.P.C) was greater than of mortar with (S.R.P.C)&( W.P.C)by (23%,17%,16%) ,(35%,29%,28%) at age (3,7,28) days respectively. The modulus of rapture of mortar with (O.P.C)was greater than of mortar with (S.R.P.C)&( W.P.C) at age (28)days by (23%,25%) respectively. The results showed that shrinkage cracks in samples occurred in mortar with (O.P.C), (S.R.P.C) & (W.P.C) at age (21,24,28)days after casting respectively. The crack width development of the sample with (O.P.C) was higher than the crack width development of the sample with (S.R.P.C) until age of (66) days , and after that decreased , but the crack width development of the sample with (W.P.C)stayed lower than the crack width development of the sample with (O.P.C)& (S.R.P.C) at all ages .