Study of the interaction between expanded vermiculite and lignosulfonate on the thermomechanical properties of coating mortars

Abstract

The search for building materials that ensure energy efficiency in buildings is becoming greater. The partial replacement of sand by porous aggregates, has great potential for modifying the thermal properties of mortars, however, porous aggregates also reduce the mechanical strength of mortars. To get around this difficulty, plasticizing additives are employed to reduce the mixing water of the mixtures, resulting in greater mechanical resistance of the mortars. This study was to evaluate the interaction of the combined addition of expanded vermiculite with a plasticizer based on lignosulphonate in coating mortars. Mortars with a ratio of 1:3 in volume were prepared, replacing 0%, 25% and 50% of sand with expanded vermiculite and adding 0 and 2% of plasticizer additive. The resulting mortars were characterized in the fresh state and in the hardened state. The addition of 2% plasticizer to the mortar containing 50% vermiculite, besides increasing compressive and flexural tensile strength, showed an improvement in thermal insulation. This confirms that the combined use of vermiculite and lignosulfonate positively influences the thermal performance of the analyzed mortars.