Abstract:

To meet the development needs of lightweight building materials， this study addressed the issue of poor hydrophilicity of expanded polystyrene （EPS） particles by conducting a series of hydrophilic modification experiments and systematically investigated the influences of modified EPS particles on mortar properties. Single or composite surface modifications were applied to unexpanded polystyrene （PS） raw particles using polyvinyl acetate emulsion （PVAc）， sodium silicate （SS）， hydroxypropyl methylcellulose ether （HPMC）， and bentonite （BT）. After the expansion and foaming of PS raw particles，EPS lightweight mortars with density grades of 1 100 and 1 400 kg/m³ （D11 and D14） were prepared， their fluidity， compressive strength， water absorption， drying shrinkage， thermal conductivity，sound absorption and insulation properties， as well as microscopic interfacial morphology， were examined. The results show that that surface modification of PS raw particles significantly enhances the surface hydrophilicity of EPS particles， effectively improves the interfacial bonding between the foamed particles and the cement matrix， and thereby comprehensively enhances mortar performance. The maximum compressive strength reaches 10.3 MPa （an increase of 87.3% increase） for the D11 and 21.8 MPa （an increase of 61.5% ） for D14. The water absorption and drying shrinkage of mortar decrease， with maximum drying shrinkage reductions of 44.0% （D14） to 53.9% （D11）.Furthermore， the thermal conductivity of the mortar remains at a low level of 0.070~0.122 W/（m·K）， demonstrating potential for integrated self-insulation and structural applications.

Key words: expanded polystyrene, hydrophilic modification, lightweight insulation, performance optimization