Structural Performance of Self-Consolidating Concrete Used in Confined Concrete Columns

Abstract

One way to reduce the intensive labor demand for vibration of highly congested sections of reinforced concrete is to use self-consolidating concrete (SCC). SCC can spread rapidly into place and fill the formwork without any mechanical consolidation and with minimum risk of separation of the material constituents. This article reports on a study that compared the structural performance of highly confined concrete columns case with normal concrete (NC) and with SCC. The effects of concrete compressive strength (40 to 80 MPa), confining stirrup configuration, and stirrup yield strength (400 and 800 MPa) were also evaluated. A total of 16 columns were tested in this experimental investigation: 11 were cast either with NC or SCC in reinforced sections; five accompanying columns were cast without reinforcement. Three of the unreinforced columns were tested in uniaxial compression to determine the overall concrete compressive strength of the large-scale columns, while two others were cored to determine the distribution of the in-place compressive strength and modulus of elasticity along the column height. The test results on reinforced columns showed that SCC yielded greater ductility, although it developed slightly lower ultimate compressive strength than NC. The study also confirmed that an increase in the stirrup yield strength can generate a high degree of confinement in well-confined concrete columns provided that stirrup spacing is kept small. The coring of unreinforced concrete columns demonstrated that the distribution of in-place properties over the column height is more homogeneous in the case of SCC than NC, which was also found to be generally adequate. Columns made with high-yield-strength ties provided significantly better confinement than similar columns made with normal-strength ties, regardless of concrete type. The authors conclude that confinement was more effective in normal strength concrete than in high-strength concrete.