Evaluation of the Design Mix Proportion on Mechanical Properties of Engineered Cementitious Composites

Abstract

This paper investigates the mechanical properties of engineered cementitious composites (ECC) in terms of compressive strength and flexural behaviour. A new version of ECC made of cement, ground granulated blast-furnace slag (GGBS), local sand, polypropylene (PP) fibers, water and superplasticizer (SP) was employed in this study. Few series of ECC mixtures were designed, cast, and tested in compression and flexural after 28 days of curing. The effect of the fiber content and sand content were studied in different cement-GGBS combination. Compression test results indicated that all ECC mixtures obtained at least 1.8 times compressive strength compared to normal concrete. They also demonstrated more ductile flexural behavior compared to normal concrete from three-point bending test. Increasing fiber content from 1.5% to 2.0% and 2.5% has negative effect on compressive strength but significantly improved modulus of toughness of ECC mixtures. The compressive strength of ECC was reduced when the sand to binder ratio adjusted to 0.4 and 0.6. The flexural behaviour of ECC was slightly improved with the increasing of sand content.

Compression and Flexural Behavior of ECC Containing PVA Fiber

“…The amount of water, superplasticizer, and silica sand were almost identical for all ECC design mixes, as shown in Table 1. Moreover, Table 1 also indicated the design mix proportions from the previous study compared to the design mixtures of ECC in this study (Lee et al, 2018b). With an exception for the river sand, which was substituted with silica sand and PVA fibers were replaced by PP fibers, all other ingredients were identical under the same series of ECC design.…”

“…For PVA fibers, the diameter and the length were 40 μm and 8 mm, respectively. The tensile strength of this fiber was 1600 MPa,ea density of 910 kg/m 3 were employed, and local river sands below 600 μm were incorporated in the cementitious matrix (Lee et al, 2018b). (Lee et al, 2018b).…”

“…There are few types of fibers commonly employed in ECC mixtures, and it is found that ECCs that contain polyvinyl alcohol (PVA) fibers have consistently exhibited excellent durability, greater mechanical properties as well as enhanced structural performances (Meng et al, 2017;Pakravan et al, 2018;Yang & Li, 2014). Some researchers explored the use of polypropylene (PP) fibers instead of PVA in the making of ECC, together with some of the locally available materials (Zhang et al, 2014;Zhang et al, 2015;Lee et al, 2018b;Lee et al, 2019a, Lee et al, 2019bZhu et al, 2020). In one of these studies, PP fibers of volume fractions 1.5%, 2.0%, and 2.5% were employed in ECC with GGBS to study the flexural strength and ductility (Lee et al, 2018b).…”

“…Some researchers explored the use of polypropylene (PP) fibers instead of PVA in the making of ECC, together with some of the locally available materials (Zhang et al, 2014;Zhang et al, 2015;Lee et al, 2018b;Lee et al, 2019a, Lee et al, 2019bZhu et al, 2020). In one of these studies, PP fibers of volume fractions 1.5%, 2.0%, and 2.5% were employed in ECC with GGBS to study the flexural strength and ductility (Lee et al, 2018b). The results showed that ECC with PP fibers could not achieve the strain-hardening behavior under the three-point bending test.…”

“…Another investigation by Lee et al (2019a) reported that tensile softening behavior of ECC specimens was observed under direct tensile test. Therefore, this study aims to investigate the performance of ECC under compression and flexural loadings by substituting PP fibers with PVA fibers in the ECC design mix, as stated in Lee et al (2018b). A compression test is accepted as the most basic test to determine the compressive strength for any cementitious material.…”