The effects of internal curing using crushed brick on the structural behaviours of high performance concrete beams

Abstract

The durability of concrete is an important factor in assessment of concrete elements that require long service lives, particularly elements used in infrastructure systems such as roads and bridges which have high construction costs. The purpose of this research is to investigate the potential for enhancement of the properties of high performance concrete (HPC) girders in terms of both their structural behaviours and mechanical properties using the internal curing method. In this research, crushed brick was implemented as a partial replacement for fine aggregate as an internal curing material. Three different mixes were made, and each mix was tested in the structural field within reinforced concrete beams (1700*150*100 mm), concrete cubes, and cylinders to examine the mechanical properties of the high performance concrete. The first reference mix had no crushed brick replacement, but the two others were brick mixes with 5 and 10% partial replacement of fine aggregate. Tests were carried out at three different ages (28, 90, and 150 days) to examine the effects of age on the enhancement of properties. A high improvement in ultimate load capacity was recorded at later ages with the 10% brick mix, which increased the load capacity by 18.5% at 90 days. Improvement of the compressive and tensile properties of 12.5% was seen for both mixes, despite the fact that the use of crushed brick decreased the ductility of the beams when compared with the reference mix. In general, the obtained results showed that using crushed bricks as an internal curing material can improve the structural and mechanical properties of high performance concrete and improve its durability by showing enhancement with respect to the age of the piece.