Green materials for construction industry from Italian volcanic quarry scraps.

• Volcanic scraps was used as raw material for geopolymers and inorganic foams. • Porosity, microstructure and moisture behaviour of geopolymers were studied. • Feasibility of porous alkali activated materials starting from volcanic scraps. • Pumice-based geopolymer could be used for indoor applications. Italian volcanic quarry scraps, with fine particle size and of little market interest, have been considered for the manufacturing of lightweight geopolymers and highly porous foams. Both powders have been alkali activated with NaOH solution at 8 M and 3 M, respectively. Geopolymers were characterized in terms of density, porosity, humidity absorption/desorption, mechanical strength and microstructure. All samples (with a bulk density of 1.5–1.6 g/cm3) exhibited a porosity of approximatively 35 vol% but featured a quite variable compressive strength (3–7 MPa), depending on the use of pumice or lapillus. The same quarry scraps were easily converted into highly porous foams (porosity of 75 vol%), by intensive mechanical stirring of alkali-activated suspensions, with the help of a surfactant. [ABSTRACT FROM AUTHOR]