Development of low drying shrinkage foamed concrete and hygro-mechanical finite element model for prefabricated building fasçade applications

Abstract

Prefabricated lightweight concrete building fas cade can improve the energy e ciency of buildings and reduce the carbon emission of transportation. However, it is essential to maintain the dimensional stability of the full scale element. The drying shrinkage of lightweight foamed concrete was investigated in this study. The hypothesis of using the drying shrinkage of normal weight concrete to approximate that of lightweight foamed concrete of dry density about 1,500 kg/m3 counterpart was veri ed. Three di erent strategies of reducing drying shrinkage were studied. The drying shrinkage of common ingredients of ordinary Portland cement (OPC) and ground granulated blast-furnace slag (GGBS) was commonly up to 2,000-3,000 ". The use of magnesium expansive agent with di erent calcination conditions could not reduce the drying shrinkage. The use of calcium sulfoaluminiate(CSA) cement with OPC and GGBS could signi cantly reduce the drying shrinkage within 1,000 " in standard testing environment. The formulation developed in laboratory was scaled up in a concrete production plant for prefabricated concrete elements. A lightweight full scale panel (the wet density was about 1,700 kg/m3) was fabricated. The drying shrinkage of the developed formulation with CSA cement was only 161 " in the eld test. A hygro-mechanical model was developed to model the di usion, shrinkage and plastic strain evolution. The incremental stress-strain constitutive relationship of the hygro-mechanical model was derived for incorporating it into general nite element routine. The model parameters were calibrated by the drying shrinkage measurements in this study. The calibrated model demonstrated the cracking potential of three typical reinforced concrete panels of three di erent formulations studied in this study.