Abstract: Macro defect free cementitious products are obtained by curing or firing a cementitious composition comprising water, a reactive filler and a water soluble alkali metal silicate.The products show good strength and heat and water stability, by contrast with known mdf products where leaching out of the polymers used results in decreased strength.

Abstract: The invention provides articles made of polymer-modified cement mortars and concretes and processes for the production thereof. The processes comprise curing compositions which contain hydraulic cement and aqueous dispersions of polymers or copolymers of methacrylic or acrylic acid esters by means of a two stage curing process the first stage of which is carried out at an elevated temperature under conditions of high humidity and the second stage of which is carried out under drying conditions, preferably at elevated temperatures. The cement mortar and concrete articles according to the invention have relatively high Modulus of Rupture (MOR) values and preferably are roof tiles or shingles or other articles of relatively thin cross-section.