Enhanced strength and self-healing properties of CA-Mg2/PVA IPN hydrogel used for shot-membrane waterproofing materials

Waterproofing layers play a pivotal role in tunnel engineering and building basements. Magnesium acrylate (CA-Mg 2 ) shot-membrane waterproofing materials- commonly used as a waterproof layer- is a type of hydrogel. Poly(vinyl alcohol) (PVA) solution subjected to freezing/thawing treatment has been added to a CA-Mg 2 monomer, resulting in the formation of a CA-Mg 2 /PVA interpenetrating polymer network (IPN) hydrogel which can produced by a redox initiation system. This new IPN hydrogel contains not only a CA-Mg 2 network formed with Mg 2+ coordination bonds, but also a PVA network created by hydrogen bonding between hydroxyl groups. In comparison to CA-Mg 2 hydrogels, the fracture stress of the CA-Mg 2 /PVA hydrogel increased from 0.45 MPa to 0.72 MPa, elongation from 602% to 854%, and the self-healing efficiency of the IPN hydrogel reached 99.9% over 3 h. A new shot-membrane waterproofing materials based on the CA-Mg 2 /PVA hydrogel was prepared and its fracture stress was 1.44 MPa, and self-healing efficiency 80%, at 3 h. In addition, damage to the hydrogel could be repaired repeatedly.