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

Hong Joon Choi, Min Jae Kim, Taekguen Oh, Yun Sik Jang, Jung Jun Park, Doo Yeol Yoo

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article number104912
JournalJournal of Building Engineering
Publication statusPublished - 2022 Oct 1

Bibliographical note

Funding Information:
In this study, the compressive strength test method based on the ASTM C109 standard was used [52]. A 50 × 50 × 50 mm cubic specimen was manufactured for the compressive strength test. A universal testing machine (UTM) was used to conduct the compressive strength tests. The maximum load capacity of the device was 3000 kN, and a uniaxial load was applied steadily during the test. The loading rate was maintained at 0.1 mm/min. The direct tensile test method from the Japan Society of Civil Engineers (JSCE) was adopted to conduct the tensile tests [53]. The specimen design and setup of the test are presented in Fig. 3. A large dog-bone-shaped specimen was prepared for tensile testing. The total length of the specimen was 330 mm, and the thickness was constant at 13 mm in each part. The neck part at the center of the specimen had a narrower width than the other parts. Through this, cracks were induced and concentrated in the neck region. In the tensile test, a different type of UTM from the device used in the compressive strength test was used. The UTM used for the tensile test had a 250 kN of maximum load capacity, and a loading rate of 0.4 mm/min. One end of the UTM consists of a pin support, while the other end is formed with a fixed support. According to Kanakubo [54], the secondary moments on test specimens after cracking can be reduced through this structural formation. During the tensile test, cracks occasionally occurred in other areas, including the neck region, which caused errors in the measured displacement. Therefore, two linear variable displacement transformers (LVDTs) were installed on the neck to record the displacement of only one part. Each LVDT can measure up to 10 mm of displacement; the displacement was recorded 20 times per second. All the specimens were coated with polyurethane spray to check for cracks on the surface after the tensile test. The number of cracks was calculated by measuring the number of all cracks on the edge of neck part and then dividing it in half. Average crack spacing was also computed by measuring the distance between the two farthest cracks among the identified cracks and then dividing it by the number of cracks. Checking the number of cracks and the width between different cracks can implicitly support the results of tensile tests, such as ductility.As the gap between the specimens in terms of tensile strength was not large, the trend of the strain energy density (g-value) was similar to that of the strain capacity. The three specimens showing the best performance were D-40, C-40, and A-40 in that order, same as the order in the highest strain capacity, indicating that the absence of SF (a combination of only OPC, CKD, and GGBS) resulted in an extremely low tensile performance of the B specimens. The tensile strength and strain capacity of B-40 were almost the lowest by a narrow margin, and its g-value was the lowest. The effect of adopting SF was more pronounced than that of other specimens cured at 40 °C. B-40 presented the lowest value among the 40 °C cured specimens in terms of compressive strength, tensile strength, strain capacity, and g-value. Therefore, SF is an important material for improving the strength and ductility of SHCC under 40 °C curing conditions. This result is supported by previous studies showing that the addition of SF can improve the compactness of the cementitious matrix and the distribution of fibers. Xuan et al. [64] reported that the addition of SF to cement composites improves the microhardness of the matrix. Moreover, the existing SF helps decrease the size of the pores in the matrix, which leads to a denser matrix of cement composites. In accordance with Nolan et al. [65], the amount of bleed water can be significantly reduced, resulting in an increase in the compactness of the matrix owing to SF. Ivorra et al. [28] explained that the small particle size of SF can allow higher transportation ability, contributing to optimizing the fiber distribution within the cement matrix. In addition, Wu et al. [29] concluded that the mechanical capacity of UHPC was maximized when SF composed 10–15% of the total binder due to the superior viscosity, which sustained an adequate distribution and orientation of the fibers. When an excessive amount of SF was added, the viscosity of the composite increased dramatically. A high level of viscosity causes inordinate aggregation between the fibers, which adversely affects the distribution and orientation.This work is supported by the Korea Agency for Infrastructure Technology Advancement (KAIA) grant funded by the Ministry of Land, Infrastructure and Transport (Grant: 22SCIP-B149189-05).

Funding Information:
This work is supported by the Korea Agency for Infrastructure Technology Advancement (KAIA) grant funded by the Ministry of Land, Infrastructure and Transport (Grant: 22SCIP-B149189-05 ).

Publisher Copyright:
© 2022 Elsevier Ltd

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Architecture
  • Building and Construction
  • Safety, Risk, Reliability and Quality
  • Mechanics of Materials


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