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2 Archives of Civil and Mechanical Engineering

2 2022

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Study on the mechanical behaviors and failure mechanism of polyurethane cement composites under uniaxial compression and tension

Yilin Pi, Wenhua Zhang, Wanting Zou, Yunsheng Zhang

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 1

art. no. e18, 2022

The brittle nature of concrete limits the further development, while the addition of polymer can enhance the toughness and improve the working performance. Understanding the mechanical properties and failure mode of polyurethane cement composites (PUCC) is of great significance in the field of construction engineering. To solve these issues, in this paper, the tensile and compressive properties are studied. The tensile/compressive strength, elastic modulus, toughness, strain capacity and the failure mechanism were analyzed. The results showed that compared with the reference group (RF), the compressive strength of PUCC was decreased by 33%. However, rubber powder could enhance the toughness of samples up to 1.19 times than RF. Polyethylene fiber was hard to disperse because of the poor fluidity of the matrix, therefore, the mechanical properties of PUCC did not change obviously. But due to the bridging effect of fiber, the failure mode was relative intact. Not only the irregular shape of basalt would decrease the interfacial adhesion, but also the polyurethane has weakened the cohesion. The mechanical properties of concrete were reduced because of the formation of interfacial transition zone between basalt and cement matrix. Therefore, the tensile and compressive strength was decreased by 19.7% and 11.8%, respectively. Moreover, the incorporation of basalt shortens the deformation time and intensifies the failure degree of the specimen. Moreover, this study takes a three-stage model to describe the compressive stress–strain behavior of PUCC. There is a good correlation between the constitutive model and the experimental results, and the simulation is accurate.

Dynamic impact compressive performance of expanded polystyrene (EPS)-foamed concrete

Yuan Chen, Wenhua Zhang, Lei Zhang, Wanting Zou, Yunsheng Zhang

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 4

art. no. e164, 2022

The mechanical property and thermal insulation capacity of EPS concrete will be reduced due to the uneven distribution and float of EPS particles. In this study, an effective strategy for resolving these issues is provided. Physical foaming was mostly employed in this process to prepare foam and inject it into EPS concrete. Different EPS contents and particle sizes were used to make the 11 groups of novel EPS-foamed concrete specimens. The Split Hopkinson Pressure Bar (SHPB) was used to investigate the dynamic impact performance of the new EPS-foamed concrete. The dynamic increasing factor (DIF), peak stress, energy absorption capabilities, and stress–strain curves were all reviewed. The findings revealed that when the amount of EPS in the system increased, the peak stress fell and the energy absorption capacity gradually increased. The energy absorbed was increased by 7–8 times in comparison to specimens lacking EPS. Furthermore, the optimal EPS con-tent ranged between 30 and 40% by volume. The EPS particle size had a significant impact on the specimen strength under dynamic impact load when the density was the same. It was determined that the optimal distribution of EPS particle size was 3–5 mm, based on the test results and the degree of specimen damage. Under the dynamic impact with the best particle size, EPS-foamed concrete demonstrated a relevant excellent energy dissipation capability, with a maximum DIF of 9.16.