Optimisation of the Mechanical Properties and Mix Proportion of Multiscale-Fibre-Reinforced Engineered Cementitious Composites

Abstract

Engineered cementitious composites (ECCs) are cement-based composite materials with strain-hardening and multiple-cracking characteristics. ECCs have multiscale defects, including nanoscale hydrated silicate gels, micron-scale capillary pores, and millimetre-scale cracks. By using millimetre-scale polyethylene (PE) fibres, microscale calcium carbonate whiskers (CWs), and nanoscale carbon nanotubes (CNTs) as exo-doped fibres, a multiscale enhancement system was formed, and the effects of multiscale fibres on the mechanical properties of ECCs were tested. The Box-Behnken experimental design method, which is a response surface methodology, was used to construct a quadratic polynomial regression equation to optimise ECC design and provide an optimisation of ECC mix proportions. The results of this study showed that a multiscale reinforcement system consisting of PE fibres, CWs, and CNTs enhanced the mechanical properties of ECCs. CWs had the greatest effect on the compressive strengths of highly ductile-fibre-reinforced cementitious composites, followed by CNTs and PE fibres. PE fibres had the greatest effect on the flexural and tensile strengths of high-ductility fibre-reinforced cementitious composites, followed by CWs and CNTs. The final optimisation results showed that when the ECC matrix was doped with 1.55% PE fibres, 2.17% CWs, and 0.154% CNTs, the compressive strength, flexural strength, and tensile strength of the matrix were optimal.

Recent Advances in Whiskers: Properties and Clinical Applications in Dentistry

“…They can be used to manufacture various types of materials, such as ion exchange resins, activated carbon, molecular sieves, and components used in fine chemicals, 70 , 71 The adsorption properties, specific surface area, and ionic conductivity of these whiskers can be altered to a certain extent, allowing them to have more functions and applications. 72 Inorganic salt whiskers mainly include CaSO 4, 73–75 CaCO 3 , 76 , 77 magnesium oxide(MgO), 72 , 78 zinc sulfide(ZnS), 79 and TiO₂, 80 , 81 which have a wide range of applications in the industrial field. CaSO 4 whiskers are mainly used for reinforcing and toughening polymer materials such as plastics, rubber, and coatings.…”

Bending Fatigue Properties of Ultra-High Toughness Cementitious Composite (UHTCC)

“…This includes mixing fibers with varying stiffness, elastic modulus, or scale to enable different fibers to function optimally at different stress stages, thereby enhancing the mechanical properties of the composite materials [28,29]. Yang [30] developed a multiscale reinforcement system using millimeter-level PE fiber, micro-scale calcium carbonate whisker, and nano-scale carbon nanotubes as externally doped fibers. The results indicated that calcium carbonate whisker exerted the greatest influence on compressive strength, while polyethylene fiber had the greatest impact on bending and tensile strength.…”