CREEP Coefficient and Specific Creep of Engineered Cementitious Composite -Bendable Concrete

Creep is a complex behavior of concrete since it induces different stages of response under loading and unloading with time. It represents the time-dependent strain as a result of a constant sustained load applied with time. In cementitious materials such as engineered cementitious composite concrete, ECC, the loaded cement paste is the principal source of creep strain. Therefore, investigating the overall creep behavior, under the loading and unloading stages, will be beneficial in providing data for the performance of ECC concrete. The test for compressional creep strain is done according to the ASTM C- 512 under controlled temperature (21 oC) and relative humidity (40%). In this research, the loading stage lasted for 9 months, and the unloading stage lasted 3 months. The total creep strain, creep coefficient, and specific creep were recorded for six ECC concrete mixes. The mixes have two strength levels, 30 and 60 MPa at 28 days, and contain polypropylene and polyvinyl alcohol fibers. Results revealed significant enhancement, and lower creep behavior, in mixes including fibers compared to plain mixes. The best promising results for the creep coefficient and specific creep were recorded when using mixes of 60 MPa containing polyvinyl alcohol fibers compared to plain mixes.