Physical properties and microstructure of ceramic–polymer composites for restoration works

Cement mortars prepared with steatite particles have been investigated for restoration of sculptures and other craftworks. This work investigates the addition of a thermoset polymer into cement-based composites reinforced with residues of steatite particles in order to seal the open pores, reduce water penetration and thus enhancing the material's lifetime. A full factorial design of 2141 type was carried out to investigate the effect of the steatite particle size and polymeric fraction on the physical and mechanical properties of the composite materials, such as bulk density, apparent porosity, elastic modulus and compressive strength. Scanning electron microscopy (SEM) was used to reveal features in the microstructure that are related to the physical properties. Results have shown that highest compressive strength (43 MPa) and lowest apparent porosity (0.19%) are achieved when steatite particles are coarser (ranging from 1.41 mm to 0.42 mm) and 40% of polymeric phase is employed. The composite with best performance also presented texture and colour quite similar to the surface characteristics of the natural soap-stone, which makes it suitable for restoration purposes.

► Density, porosity and modulus decreased, whereas strength increased with polymer addition larger steatite particles.
► An interaction effect was found for the porosity.
► The material colour was similar to soapstone being useful for restoration works.