Field investigation and finite element analysis on expansion and shrinkage strains of expansive concrete structures

This study investigated the strain behavior of various reinforced concrete structures cast with expansive concrete. Laboratory tests, field measurement, and finite element (FE) analysis on the expansion and shrinkage were investigated. Field measurement and numerical simulation were carried out on three different structures, i.e., slab on grade (SG), slab on beam (SB), and water tank wall (WT). Strain gauges are installed in several locations in each structure to study the effects of type and amount of expansive additive and restraining conditions on the level of expansion and shrinkage. To increase the flexibility and versatility of the design process, FE analysis is one of the comprehensive methods for estimating the expansion and shrinkage strain in expansive concrete structures under restraint. FE analysis in this study applies free expansion strain as an input, with the consideration of expansion loss due to pores filling of expansive products and early age compressive creep. The field measurement results indicated that the restraint (internal and external restraint) significantly affects the expansion and shrinkage strains in the structures. Furthermore, it was found that the application of effective free strain as the input in the FE analysis made it possible to predict the level of restrained expansion strain in expansive concrete structures. The expansion and shrinkage strains can be estimated accurately using the FE analysis by considering several factors such as degree of restraint, curing conditions, and mix proportions.