Effect of Re-vibration on Strength Properties of Lightweight Concrete

Abstract

In relatively deep structural members, re-vibration is applied to sequential layers after they are initially hardened. This may cause harmful effects on strength properties, especially on lightweight concrete (LWC). In this experimental study, the effects of re-vibration on LWC properties were thoroughly investigated. Local lightweight crushed pumice rock named “Bonza,” as well as set retarding admixture and silica fume (SF) were used to produce four different mixes of LWC. These mixes were re-vibrated at different time lags (0:00, 2:50, 4:30, and 5:30 [h:min]). After the re-vibration process, compressive and tensile strength properties, as well as pulse velocity, density, and permeable voids volume of hardened concrete mixes, were investigated. Results showed that using the setting retarder and partial SF replacement of Portland cement, the density, compressive, and tensile strength properties were increased in all re-vibrated mixes when the re-vibration was accomplished before the final set time of the cement. A lack of correlation between ultrasonic pulse velocity, density, and compressive strength was also detected. Furthermore, a linear relationship was found between permeable voids volume and compressive strength of all mixtures.