Brazilian disc splitting tensile test aerogel alkali activators analytic hierarchy process anchoring behavior autogenous shrinkage bond behaviour bond stress–slip curve bond–slip performance coal gangue compressive strength concrete connecting plates cracking risk damage level dredged silt drop hammer impact drying shrinkage dynamic splitting tensile properties environmentally friendly building material expansion agent experimental study fiber wrapping fly ash fracture performance freezing–thawing environment geopolymers glass fiber glass fibres hybrid fibres