Matrix design for waterproof Engineered Cementitious Composites (ECCs)

•This study reports ECCs with desired mechenical and waterproof performance.•WPA is effective in promoting the hydrophobicity of matrix and reducing the sorptivity.•SRA and CSA are beneficial to control drying shrinkage.•ECCs were loaded to and tested at tensile strain up to 0.5% for water permeability. The excellent crack control capability of Engineered Cementitious Composites (ECCs) is exceedingly beneficial for waterproofing applications. To design a suitable ECC matrix for waterproofing applications, waterproofing admixture (WPA) was added to improve the wetting property and reduce the sorptivity, and shrinkage-reducing admixture (SRA) together with calcium sulfoaluminate cement (SAC) were introduced to control the drying shrinkage. A comprehensive experimental program was conducted to optimize the use of WPA, SRA and SAC. Moreover, the water permeability of both un-cracked and cracked ECCs were examined. This work finally developed a kind of waterproof ECC, with 28-day compressive strength around 35MPa, ultimate tensile strain over 4%, a water contact angle larger than 110 degree, 28-day drying shrinkage about 2/3 the value of the typical ECC (M45), a water absorption rate around 5×10−5mm/s1/2 and a water permeability coefficient about 8×10−12m/s. The findings of this research should be rewarding for the design of ECCs for waterproofing applications.