Preparation and properties of nanopore-rich lightweight cement paste based on swelled bentonite

Abstract

Nanopore-rich lightweight cement pastes (NLCPs) were successfully prepared by adding pre-swelled bentonite to cement paste. The pore structure, thermal conductivity, and compressive strength of these pastes were investigated. The results indicated that montmorillonite layers in paste can subdivide and refine capillary voids, thereby forming nanopores. When the volume percentage of bentonite in cement paste was increased from 0% to 80%, the nanopore volume increased gradually from 0.093 cc/g to 0.654 cc/g, while the corresponding volume percentage increased from 82.1% to 90.7% and then decreased to 57.7%. More importantly, nanopores contribute to a reduction in the thermal conductivity. Adding pre-saturated bentonite to cement paste yielded NLCPs with a dry density, compressive strength, and thermal conductivity of 510 kg/m3–1873 kg/m3, 2.9 MPa–88.4 MPa, and 0.093 W/(m·K)–0.554 W/(m·K), respectively.