Quantitative evaluation on the pumpability of lightweight aggregate concrete by a full-scale pumping test

Abstract

Lightweight aggregate concrete (LWAC) shows a smaller density than regular concrete, and it is beneficial by decreasing the dead load of a structure. Pores in lightweight aggregates, which are incorporated 30% of the concrete mix by volume, contribute to the small density of LWAC. The pores, however, absorb mixing water in freshly mixed LWAC, which results in the high loss of slump and poor workability. The pumping for LWAC is even more challenging because the pumping pressure make lightweight aggregates absorb more water. This paper aimed to quantify the pumpability of LWAC by conducting a full-scale horizontal pumping. The test results give us the pressure distributions along the pipeline, the change of slump and moisture content of the mortar phase in relation to pumping pressure. These test results confirmed a remarkable decrease in the pumping efficiency of LWAC compared with normal concrete, which was originated from the degraded rheological properties of the lubrication layers. Finally, this study emphasizes that the application of LWAC without any preconditioning process requires a generous amount of mixing water to be transported by pumping.