Effect of short to long hybrid elastic/hyperelastic (Glass/PP) fibers on high-strength engineered cementitious composites (ECC), along with presenting a constitutive model
Naser Shabakhty, Hamid Reza Karimi, Abbas Yeganeh‐Bakhtiary
Abstract
The brittleness of concretes can be reduced by adding fibers. For decades, elastic fibers such as glass fiber were used in concretes, making them stronger; nowadays, significant strain-hardening behavior can be seen by using hyperelastic fibers such as polypropylene (PP) fiber, resulting in engineered cementitious composites (ECC). Although achieving a single aim, such as strength , is easier, designing a multipurpose cementitious composite with the aim for both strength and deformation needs careful micromechanical design. This study examines the performance of cementitious composites developed by hybrid fiber conditions using elastic/hyperelastic fibers (glass/PP) with proportions of 100/0, 75/25, 50/50, 25/75, and 0/100, considering fiber lengths as 12, 25, 50, and 100 mm. The tests were executed under unidirectional direct tension. The results indicate that, for tensile strength parameters, the PP fiber has privileges over glass fiber, especially with the increase of fiber length; this privilege becomes more evident. For glass fiber, the increase in fiber length (from 12 to 100 mm) changes the tensile strength from 4.7 to 6.5 MPa, while for PP, this change is 3.7–11.3 MPa. Looking at strains, the mixtures with 12 mm glass fiber have 2.5% strain, while using PP fiber with 100 mm length, an ECC with 24% strain values (with significant strain hardening is achieved. In the end, using statistical analysis, the effect of variables was studied, and it was seen that, although both fibers have a similar effect on the elastic behavior of ECCs, PP has privileges in the plastic behavior of ECCs. Also, a describing model was presented to predict the data with reasonable errors.