Towards the development of aluminum-based cellular eco-mortar containing recycled granite sand: thermophysical and mechanical properties

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Résumé

Abstract
This study focuses on the design of an eco-friendly cellular mortar for the Sudano–Sahelian hot and dry climate of Burkina Faso, containing aluminum powder and sand from the recycling of granite waste. Mortars containing two types of sand (natural sand: NS and recycled granite sand: GS) were tested with varying aluminum powder (Al) dosages (0%, 0.5%, and 1%). The sand/cement (S/C) ratios were 4, 3, and 2, and the water/cement (W/C) ratios were 0.6 to 1.2. Experiments were conducted to evaluate the physical, mechanical, and thermal properties of fresh and hardened mortar. The results show improvements in the thermophysical properties with increasing aluminum powder content and W/C ratio and decreasing S/C ratio. Adding 0 to 1% Al in the mortar, containing an S/C of 2 at a W/C of 1.2, increased its linear swelling in the fresh state up to 61%, reducing the bulk density in hardened state by 44% from 1785 to 1003 kg/m³ with GS. On the contrary, a swelling of only 50% and a reduction of density by 35% from 1796 to 1168 kg/m³ were recorded with NS, owing to the formation of cellular pores. This resulted in a decrease in thermal conductivity by 90% (0.93 to 0.09 W/m.K) with GS and by 71% (1.25 to 0.36 W/m.K) with NS, towards insulating performance. However, the compressive strength decreased from 15.5 to 2.4 MPa (-84%) with GS and from 10.3 to 7.1 MPa (-31%) with NS, with the increase in porosity. These cellular mortars offer promising alternatives to ordinary mortar in terms of lightweight, quasi-insulating properties, and potential reduction in environmental impacts from the recycling of granite sand.

Mots-clés

aluminum powder, thermal conductivity, compressive strength, bulk density, porosity, lightweight building materials, thermal insulation, hot arid climate, waste recycling, water-cement ratio, cement-sand ratio