Using Limestone Calcined Clay to Improve Tensile Performance and Greenness of High-Tensile Strength Strain-Hardening Cementitious Composites (SHCC)

Abstract

High-tensile strength strain-hardening cementitious composites (HTS-SHCC) can reduce the size of structural members, enhance the flexibility of architectural design and make 3-D printed structures without steel reinforcements possible. To produce HTS-SHCC, high-performance polyethylene (PE) fiber is widely used, due to its high-tensile strength of about 3 GPa. However, PE fiber has a hydrophobic and smooth surface, which limits the fiber/matrix interfacial bond strength. Therefore, a large dosage of very fine powders (e.g., micro silica) has been generally included in the matrix to densify the fiber/matrix interface and ensure sufficient fiber-bridging capacity. Recently, it has been proved in the literature that limestone calcined clay (LC2) system has a strong porosity refinement effect in cementitious materials. Thus, LC2 has the potential to ensure sufficient fiber/matrix frictional bond strength by replacing a fraction of cement by LC2 in HTS-SHCC, which can also reduce the material cost and the environmental impact of the materials. This paper presents a feasibility study of incorporating different dosages of LC2 (0, 20, 40, 60 and 80% of binder) in HTS-SHCC, with the focus on the tensile performance in terms of tensile strength, ultimate tensile strain and crack pattern. The findings in this study provide a new, low-cost and sustainable approach to produce HTS-SHCC.