Mechanical properties of high-strength strain-hardening cementitious composites (HS-SHCC) with hybrid supplementary cementitious materials under various curing conditions. (1st October 2022)

• Record Type: Journal Article
• Authors: Choi, Hong-Joon; Kim, Min-Jae; Oh, Taekguen; Jang, Yun Sik; Park, Jung-Jun; Yoo, Doo-Yeol
• Is Part Of: Journal of building engineering. Volume 57(2022)
• Publication Date: 2022-10-01
• Subjects: Strain-hardening cementitious composites -- Supplementary cementitious materials -- Curing condition -- Energy absorption capacity -- Strain capacity; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2022.104912
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: This study aimed to achieve improved tensile performance of strain-hardening cementitious composites (SHCCs) utilizing various types of supplementary cementitious materials (SCMs) along with polyethylene (PE) fibers. Ground granulated blast-furnace slag (GGBS), silica fume (SF) and cement kiln dust (CKD) were used as SCMs, with at least two types of SCMs incorporated into SHCC to improve the mechanical performance through hybrid effect of SCMs. Additionally, reaction sensitivity and hydration products were evaluated using specimens manufactured under various curing temperatures (20 °C, 40 °C, and 90 °C) in consideration of different chemical compositions of the SCMs. It was confirmed that the 40 °C curing condition has the most positive effect on the compressive and tensile strengths of SHCC and strain capacity. The absence of SF led to a decrease in the strain capacity, significantly affecting the low strain energy density of the corresponding specimens. The specimen cured at a temperature of 40 °C after incorporating all three SCMs exhibited remarkably long-lasting strain-hardening behavior and achieved the highest strain capacity and strain energy density among all the specimens. Crack investigation after a tensile test was conducted to confirm traces of strain-hardening behavior, which improved a reliability of the mechanical tests. Moreover, derivative thermogravimetry analysis was performed to identify the residual amounts of hydrates affecting the performance of the cement composites. The high Ca(OH)2 residue was the basis for explaining insufficient hydration reactions, and the key factors for the low strength of some specimens was found in a low produced amount of CaCO3 . Highlights: Curing temperature of 40 °C is most effective in improving the strengths and strain capacity of HS-SHCC. The absence of SF results in insufficient hydration and obvious decrease of strain capacity of HS-SHCC. The hybrid use of SF and CKD shows large amounts of hydration products, causing a higher strain energy density. SF is most important SCM to achieve superb strain-hardening characteristics of cement mortar with PE fibers.