Title: Mechanical Properties of Concrete with Recycled Aggregate at Early Ages
Author(s): Zeger Sierens and Jiabin Li
Publication: Symposium Paper
Appears on pages(s): 39.1-39.10
Keywords: recycled concrete aggregates (RCAs), precast concrete, pre-stressed concrete, strength, modulus of elasticity, early ages
Currently, recycled concrete aggregates (RCAs) are mainly used in some low-grade applications. New high-value-added applications of this kind of material are required. One possible high-end application is in precast prestressed concrete elements. Knowledge on the mechanical properties of concrete with RCAs at early ages is of crucial importance for this purpose. This paper presents a test program to examine the effect of RCAs on the mechanical properties of concrete at early ages. The main variables in the tests are the percentage of RCAs (0, 10%, 20%, 50% and 100%) and curing age (1d, 2d, 3d, 7d, 14d and 28d). The compressive strength, splitting tensile strength and modulus of elasticity of the concretes are measured. The test results indicate that the use of RCAs tends to decrease the development of the concrete strength and modulus of elasticity with time, but mainly in the first 7 days. The difference increases with the increase of the percentage of RCAs. The test data are also compared with the models in EN 1992-1-1, ACI 209 and ACI 318. It is found that the models can generally provide satisfactory descriptions of the strength and modulus of elasticity of concrete with RCAs at early ages.