Effect of pozzolanic materials and curing methods on the elastic modulus of HPC

摘要

The modulus of elasticity of a material is a fundamental property required for the proper modeling of its constitutive behavior and for its proper use in various structural applications. This paper discusses experimental evaluation of the elastic modulus of high-performance concrete made from mixes using various percentages of fly ash, silica fume, and granulated blast furnace slag. Results are compared to those from control specimens at various ages between 1 and 90 days. The results presented are part of a study for the New Jersey Department of Transportation (NJDOT) to develop and implement High-Performance Concrete (HPC) mix design and technical specifications for transportation structures. The study also investigates the effect of curing on the elastic modulus. Three methods of curing were evaluated: (1) air-dry curing, (2) curing compound, and (3) wet curing with burlap. The results showed that adding silica fume resulted in an increase in strength and modulus at early ages, however, there was no change in the modulus at 28 and 56 days. In addition, adding 20 percent fly ash with various percentage of silica fume had an adverse effect on both strength and modulus values at all ages to 90 days. It is also shown that dry curing and curing compound reduce the modulus of elasticity compared to wet curing with burlap. Results showed the elastic modulus of HPC is proportional to the compressive strength, but the prediction equations of ACI-318 and ACI-363 may not accurately predict the modulus values for high-performance concrete with pozzolans.