Study on the mechanical properties of lightweight ECC materials reinforced by composite calcium carbonate whiskers
Engineered cementitious composites(ECC),due to their tensile strain hardening behavior and unique characteristics of tight multiple cracks,ensure that they can meet the strict requirements of toughness and durability of concrete infrastructure.It uses fly ash floating beads instead of fine quartz sand as lightweight fine aggregates,uses domestically produced high-strength and high modulus PVA and PE fibers,and adds calcium carbonate whiskers to enhance ECC at multiple scales.The strength,uniaxial tensile performance,four point bending performance of thin plates,and porosity of lightweight ECC are experimentally studied.The results show that the optimal content of calcium carbonate whiskers is 1%by volume,with a compressive strength of 57 MPa,ultimate tensile strength of 4.31 MPa,and tensile strain of 3.44%for PVA-ECC.The compressive strength of PE-ECC is 60.4 MPa,the ultimate tensile strength is 4.77 MPa,and the tensile strain is 8.16%.Adding an appropriate amount of whiskers can optimize the pore structure and improve strength.The micro bridging effect of whiskers can delay the development of micro cracks.At the same time,whiskers can improve interface roughness and friction bonding strength,thereby improving residual energy to better meet energy criteria and thus improving tensile strain capacity.
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