Influence of Cement Content on Thermophysical and Mechanical Properties of Compacted Earth Bricks Made from Kaolinitic and Lateritic Soils: Experimental Study

Abstract

This study explores the impact of the cement content (4%, 6%, and 8%) on the thermophysical and mechanical properties of compressed earth bricks produced from a mixture of kaolinitic (60%), lateritic (12% - 16%), and sandy (20%) soils. The results regarding thermophysical properties indicate that an increase in the cement content from 6% to 8%, combined with a 28-day curing period, leads to a gradual increase in bulk density, from 1859 to 1863 kg/m 3 (5.9%), thermal conductivity, which ranges from 0.601 to 0.690 W/m·K (14.8%); thermal effusivity, which increases from 1202 to 1328.5 W/m 2 ·K·S 1 / 2 (+10.5%), thermal diffusivity, which rises from 2.53 to 2.71 × 10 − 7 m 2 /s (+7.1%), and a nearly constant specific heat capacity ranging from 1357.76 to 1367.54 J/kg·K (+0.7%). In contrast, thermal resistance decreased from 0.33 to 0.28 m 2 ·K/W (−15.2%). As for mechanical properties, compressive strength increased from 1.78 to 3.51 MPa (+97%) with a 4% cement addition and curing periods of 3, 7, and 28 days; from 2.34 to 4.44 MPa (+89.74%) with a 6% cement addition and curing for 3, 7, and 28 days; and from 3.03 to 6.08 MPa (+100%) with an 8% cement addition and curing for 3, 7, and 28 days. All formulations exceed the minimum compressive strength of 2 MPa generally recommended by several standards for stabilized clay bricks. The 6% and 8% formulations meet the requirements for bricks used in load-bearing walls. The 8% formulation provides very high compressive strength and can be used in sustainable construction.