Citation: Gao, S.; Xie, P. Effect of
Temperatures and Moisture Content
on the Fracture Properties of
Engineered Cementitious
Composites (ECC). Materials 2022, 15,
2604. https://doi.org/10.3390/
ma15072604
Academic Editor: Geo Paul
Received: 20 January 2022
Accepted: 25 March 2022
Published: 1 April 2022
Publisher’s Note: MDPI stays neutral
with regard to jurisdictional claims in
published maps and institutional affil-
iations.
Copyright: © 2022 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Article
Effect of Temperatures and Moisture Content on the Fracture
Properties of Engineered Cementitious Composites (ECC)
Shuling Gao
1,2,
* and Puxu Xie
1
1
School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin 300401, China;
xpx3136628063@163.com
2
Civil Engineering Technology Research Center of Hebei Province, Tianjin 300401, China
* Correspondence: gaoshuling@hebut.edu.cn
Abstract:
This research will help to improve our understanding of the fracture properties of ECC at
low temperatures (long-term low temperatures, freeze–thaw) and evaluate the safety properties of
ECC under low-temperature conditions. Three levels of saturation (saturated, semi-saturated, and
dry), four target temperatures (20, 0,
−
20, and
−
60
◦
C), and the effect of the coupled of the two on the
mode I fracture properties of ECC were investigated. Then, we compared and analyzed the fracture
properties of ECC loaded at 20 and
−
20
◦
C, after different freeze–thaw cycles (25, 50, 100 cycles),
which were compared with saturated specimens without freeze–thaw at the four target temperatures
to analyze the differences in low-temperature and freeze–thaw failure mechanisms. Temperatures
and saturation have a significant effect on the fracture properties. Low temperatures and freeze–thaw
treatments both decreased the nominal fracture energy of ECC. Distinct differences in matrix and
fiber-matrix interface damage mechanisms have been discovered. Low temperatures treatment
transforms ECC from a ductile to a brittle fracture mode. However, even after 100 freeze–thaw cycles,
it remains ductile fractured. This study complements the deficiencies of ECC in low-temperature
theoretical and experimental applications, and it sets the stage for a broad range of ECC applications.
Keywords: ECC; low temperatures; saturation; freeze–thaw; fracture toughness; fracture energy
1. Introduction
ECC (engineered cementitious composite) is a special high-performance, fiber-reinforced,
cement-based composite, which exhibits excellent strain-hardening behavior during over-
stretching the loading process [
1
–
4
]. It is equipped with several excellent properties, including
high ductility, superior crack control, self-healing, and environmental protection. The design
theory of ECC is based on micromechanics and fracture mechanics, and the stress concen-
tration, caused by external load, is relieved by multi-crack mode [
5
]. Work with cracks is its
common state. While the traditional strength theory of ECC reflects the mechanical properties
of ECC as a whole, it ignores the non-homogeneity of ECC materials and, thus, cannot fully
describe the ECC process from the crack initiation, development, connection, and formation
of macroscopic cracks to component failure. Moreover, in practical engineering applications,
ECC may generate cracks for a variety of reasons (such as drying shrinkage, temperatures
stress, external load, foundation deformation, etc.), and serious cracks can jeopardize the
integrity and stability of the structure, as well as have a significant impact on the safety of the
structure. Nowadays, in actual engineering structures, cracks in the material always occur,
posing possible safety issues, due to the “fracture” of the structure. In terms of structural
safety assessment and crack analysis, fracture mechanics are used to investigate the fracture
properties of fiber cement-based reinforced materials [
6
], which has garnered the attention
and approval of many scholars.
ECC has a wide range of potential applications and offers significant economic benefits.
Following the Three Gorges Project, the promotion of the South-to-North Water Transfer
Materials 2022, 15, 2604. https://doi.org/10.3390/ma15072604 https://www.mdpi.com/journal/materials
