The effect of superplasticizer dosage on fresh properties of self- compacting lightweight concrete produced with coarse pumice aggregate

Abstract

The use of superplasticizer in the manufacture of self-compacting concrete is graduallymore common. Each type of superplasticizer available in the market has differentcompositions, causing differences in dosage requirement. Also, superplasticizer affectthe fresh and hardened properties of concrete. In this experimental study the effect ofdifferent dosage of superplasticizer (SP) on fresh properties of self-compactinglightweight concrete (SCLC) containing coarse aggregate pumice were studied by usingfive different percentages for (SP) (1%, 1.3%, 1.5%, 1.7% and 2%) of the binderweight. (SCLCs) were produced with constant binder content of 550 kg/m 3 and at awater-to-binder ratio of 0.26. 20% of portland cement was replaced with fly ash byweight. The workability of SCLCs was quantitatively evaluated by slump flow time anddiameter, V-funnel flow time, and L-box height ratio. Moreover, compressive strengthof hardened SCLCs was measured at 28 days by using compression machine andRebound hammer test. The results show that with the increase of (SP) dosage in theconcrete mixture, the flowability increased. However, there is an optimum value of (SP).The increase of (SP) dosage is accompanied by decreasing of T 500 slump flow and V-funnel time until it reaches the optimum level. Nevertheless, excessive use of (SP) leadto increase of slump flow diameter.