Effect of Aggregate Type on Mechanical Behavior of Dam Concrete

Abstract

Due to the practical difficulties in performing a full size specimen test, dam concrete is usually sieved to remove the aggregate larger than 40 mm (1.6 in) when tested, which is called sieved concrete. This paper reports on a study that examined the influence of surface roughness of aggregate via two types of aggregates on the mechanical and fracture properties for dam and sieved concretes. The authors used two types of aggregates by full size specimens of 450 x 450 x 900 mm (18 x 18 x 35 in.) for tension and 450 x 450 x 450 mm (18 x 18 x 18 in.) for compression and by standard size specimens 150 x 150 x 550 mm (6 x 6 x 22 in.) for tension and 150 x 150 x 150 mm (6 x 6 x 6 in.) for compression, respectively. The complete stress-strain responses both in tension and compression were acquired through a systematic experimental program. The authors propose models to estimate the basic mechanical properties and the fracture parameters of the concretes with specimen ages; they propose theoretical models for normalized axial stress-strain curve in compression and for normalized axial stress versus normalized maximum crack width curve in uniaxial tension. Results include: the strengths, modulus of elasticity, and fracture energy increase with specimen age; the specimen size and maximum aggregate diameter significantly affect the fracture energy, peak strain, and crack width of concretes in uniaxial tension; and the performance of concrete with crushed coarse aggregate is higher than that of concrete with natural coarse aggregate.