Effects of combined natural volcanic powders on the thermo-physical and mechanical properties of structural eco-concrete

Abstract This paper presents an experimental investigation related to the study of the valorization of two types of natural volcanic powders: pozzolan (PZ) and perlite (P), used by substitution of cement for determination the composition of a structural eco-concrete intended for building insulation. For this reason, ten compositions were prepared by partial substitution of cement 0%, 10%, 20% and 30% by PZ and/or P. The thermo-physical and mechanical properties that have been tested are the workability, density (D), porosity (ω), compressive strength (Cs), thermal conductivity (λ), and the thermal resistance (Rth). The obtained experimental results showed that it is possible to obtain a structural eco-concrete with cement dosages of 280 kg/m3 and 315 kg/m3 by replacing the cement with 10%P, 20%PZ or 10%PZ combined with 10%P without significantly affecting the performance of concrete. The use of PZ and P decrease the slump, density and increases the porosity of eco-concretes due to their high finesse and their lower density compared to cement. At 90-days, the optimal eco-concretes made with 10%P, 20%PZ or (10%PZ+10%P) have a good compressive strength which describes the delayed pozzolanic reaction of these additions. The thermal conductivity at 365 days decreases with the increase of PZ and P. For the optimal eco-concretes made with 10%P, 20%PZ or (10%PZ+10%P), the gain in λ and Rth was lower than that of the reference concrete which shows the positive impact of these additions on the thermal properties. Finally, a good linear correlation between λ, D and ω has been determined with a higher R 2 .