Hydrothermal synthesis of an expanded perlite based lightweight composite for indoor humidity regulating

Abstract

• A lightweight tough composite could be synthesized from EP for humidity regulating. • Tobermorite formation could enhance strength and improve porosity of the material. • CaCl 2 addition could promote porosity and improve moisture adsorption/desorption. • CMC formation could form crosslinked networks thus improving humidity regulation. • Both CaCl 2 and CMC addition had large effect on regulating humidity synergetically. A lightweight and tough indoor construction material has been synthesized hydrothermally from expanded perlite (EP) with indoor humidity regulation for high-rise buildings. Due to the low-temperature (≤473.15 K) hydrothermal treatment, the original porosity of EP was remained in the matrix to serve a low density (<0.900 g/cm 3 ). The formation of C S H and tobermorite could not only enhance the flexural strength of the composite (greater than 16.0 MPa), but also improve its porosity. The CaCl 2 addition had a capability of promoting the porosity and improving the moisture adsorption/desorption capacity. The CaCl 2 solution could make more moisture adsorbed in pores and more pores possess the humidity self-regulation ability. The CMC addition could generate crosslinked networks and high osmotic pressure to promote humidity self-regulating performance greatly. Furthermore, the addition of both CaCl 2 and CMC exerted a synergetic effect to further reinforce moisture adsorption capacity (∼380 g/m 2 ).