Ghannadi - Inst. of Civil Eng. Dept., Islamic Azad University, Sarab, Iran
zandi - Assist. Prof. of Civil Eng. Dept., Islamic Azad University, Tabriz, Iran
eimani - Assist. Prof. of Civil Eng. Dept., Mohaghegh Ardabili University, Iran.

This paper presents the results of laboratory study carried out on effect of using the simultaneous of microsilis,super plasticizer and air entrain additives on compressive strength of light weight perlite concrete. In this study, 63 test specimens with different percentage and mixtures including microsilis, super plasticizer and air entrain were used. 63 test specimens with different percentage and mixtures including microsilis and super plasticizer were also prepared for comparison purposes. In the mixtures, lightweight perlite aggregate, microsilis, super plasticizer, air entrain, cement type I, sand and water were used. Laboratory test results showed that workability and compressive strength of lightweight perlite concrete was increased by the use of air entrain. In this study water/cement ratio is permanent and we know that compressive strength of concrete is depends on it. Since, it was expected that the use of air entrain and super plasticizer lower water/cement ratio and raised strengths,considerably. However, the use of air entrain additive seems to be mandatory for the increase of workability and compressive strength of light weight perlite concrete. It was concluded that air entrain was better than super plasticizer in increased of compressive strength. Since, this ideology was repelled that use of air entrain additive decreased the strength, usually

perlite, microsilis, air entrain, super plasticizer