AbstractMoulded microporous samples composed of calcium silicates, xonotlite, and tobermorite, wereformed by a one-step hydrothermal synthesis reaction. The properties obtained are: 0·131–0·191 kg m−3density, 0·51–0·90 MN m−2compressive strength, 0·25–0·40 MN m−2flexural strength, 0·0462 Wm−1K−1(24°C) thermal conductivity, and 1·93% linear shrinkage under firing temperature 800°C for 24 h. The process developed was made possible by the use of accelerating admixtures, which include magnesium acetate and gypsum.MST/1133