Title: CREEP AND SHRINKAGE OF NORMAL STRENGTH CONCRETE WITH RECYCLED CONCRETE AGGREGATES
Author(s): Adam M. Knaack and Yahya C. Kurama
Publication: Materials Journal
Appears on pages(s): 451-462
Keywords: creep compliance; recycled concrete aggregate; shrinkage.
This paper describes an experimental investigation on the creep and shrinkage of normal-strength concrete with recycled concrete aggregates (RCA) as replacement for coarse natural aggregates (for example, crushed stone and gravel). Three RCA sources and two aggregate replacement levels were used; additional parameters were curing conditions, loading age, and axial stress level. It was found that RCA significantly increases the creep and shrinkage deformations of concrete, but this increase is smaller than the effect of RCA on the initial (that is, immediate mechanical) deformations. The creep compliance increases with increased loading age of RCA concrete, in a similar manner as for conventional concrete. Out of the three materials tested, the RCA producing the smallest concrete
compressive strength resulted in the largest creep compliance.
Adjustment factors were determined for code-based creep models to predict the creep deformations of RCA concrete. The use of these factors is intended to be similar to other code-based adjustment factors for “nonstandard” conditions (for example, loading age).