Effect of freeze and thaw cycle on the mechanical properties of engineered cementitious composites with un-oiled fibers containing liquid and solid polymers

Nowadays, the application of the engineered cementitious composites(ECC) is expected to highly develop. Due to the lack of access to oiled- polyvinyl alcohol (PVA) fibers in many parts of the world, the implementation of the ECC has contained many difficulties. In this study, to increase the mechanical properties of ECC with the use of un-oiled PVA fibers, the polymers of styrene butadiene rubber (SBR), and ethylene vinyl acetate (EVA) were taken into account to resolve the abovementioned issue. Herein, also in order to enhance the tensile and flexural properties of ECC, the cement was replaced by polymers. Accordingly, a total of 7 mix designs were planned to conduct the proposed tests. The compressive strength, uniaxial tensile strength, and three-point bending tests were performed on the ECC at their 28-day age with consideration of the freeze and thaw cycle. The results of this research illustrated that the use of polymers can enhance the tensile and flexural properties of the ECC with un-oiled PVA fibers. The tensile strain in this study increased by more than 3% after the application of the polymers. Furthermore, the compressive strength increased by more than 47 MPa, and the deflection at the mid-span reached more than 9 mm in the bending test. However, the results showed that the use of polymers was effective on the freeze and thaw cycle and almost preserved the mechanical properties of the ECC. SBR latex has higher compatibility with the ECC in comparison with EVA powder.

The Effect of Elevated Temperature on Engineered Cementitious Composite Microstructural Behavior: An Overview

This paper discusses the quantitative bibliographic data derived from scientific publications on Engineered Cementitious Composites (ECC) subjected to elevated temperature, the influence of elevated temperature on the mechanical properties, particularly the compressive strength and microstructure behavior of Engineered Cementitious Composites (ECC) mixtures based on the review of previous pieces of literature. Systematic literature reviews were employed as the methodology in this study. The age of related publications selected to be reviewed was limited to publications for the past ten years, 2010 to December 2020. It was found from available research that exposure of the ECC specimen at the elevated temperature starting from 200oC significantly reduced the compressive strength when the temperature increases, melting of fiber and increase of porosity causes the dramatically increase micro-cracks.

Investigation of the Mechanical, Microstructure and 3D Fractal Analysis of Nanocalcite-Modified Environmentally Friendly and Sustainable Cementitious Composites

Unlike conventional concrete materials, Engineered Cementitious Composites (ECC) use a micromechanics-based design theory in the material design process. Recently, the use of nanoparticles in various concretes and mortars has increased. This study used nanocalcite to investigate the mechanical, microstructural fractal analysis of environmentally friendly nanocalcite-doped ECC (NCa-ECC). This paper investigated the effects of nanocalcite (NCa) with different contents (0.5, 1, and 1.5% by mass of binder) on the mechanical properties of engineered cementitious composites (ECC). For this purpose, compressive strength, ultrasonic pulse velocity (UPV), and flexural strength tests were conducted to investigate the mechanical properties of the ECC series. In addition, SEM analyses were carried out to investigate the microstructural properties of the ECC series. The content of nanocalcite improved the mechanical and microstructural properties of the nanocalcite-modified ECC series. In addition, the 1 NCa series (1% nanocalcite modified to the mass of the binder) had the best performance among the series used in this study.