Physico-Mechanical and Hygro-Thermal Properties of Compressed Earth Blocks Stabilized with Industrial and Agro By-Product Binders

Abstract

This study investigated the engineering properties of compressed earth blocks (CEBs) stabilized with by-product binders: calcium carbide residue (CCR) and rice husk ash (RHA). The dry mixtures were prepared using the earthen material and 0–25 wt% CCR, firstly, and 20 wt% CCR partially substituted by the RHA (CCR:RHA in 20:0–12:8 ratios), secondly. The appropriate amount of water was thoroughly mixed with the dry mixtures. The moistened mixtures were manually compressed into CEBs, cured, dried, and tested. The stabilization of CEBs with CCR increased the dry compressive strength (CS) from 1.1 MPa with 0% CCR to 4.3 MPa with 10% CCR and above; decreased the bulk density (ρb:1800–1475 kg/m3) and increased the total porosity (TP:35–45%). This resulted in the improvement of the coefficient of structural efficiency (CSE: 610–3050 Pa∙m3/kg). It also improved the thermal efficiency given the decrease of the thermal conductivity (λ: 1.02–0.69 W/m∙K), thermal diffusivity (a: 6.3 × 10−7 to 4.7 × 10−7 m²/s) and thermal penetration depth (δp: 0.13–0.11 m). The RHA further improved the CS up to 7 MPa, reaching the optimum with 16:4 CCR:RHA (ρb: 1575 kg/m3 and TP: 40%). The latter reached higher CSE (4460 Pa∙m3/kg) than cement stabilized CEBs (3540 Pa∙m3/kg). It reached lower λ (0.64 w/m∙K), a (4.1 × 10−7 m²/s) and δp (0.11 m) than cement CEBs (1.01 w/m∙K, 6.8 × 10−7 m²/s, and 0.14 m). Additionally, the stabilization of CEBs with by-products improved the moisture sorption capacity. The improvement of the structural and thermal efficiency of CEBs by the stabilization with by-product binders is beneficial for load-bearing capacity and thermal performances in multi-storey buildings.

Hydric and Durability Performances of Compressed Earth Blocks Stabilized with Industrial and Agro By-Product Binders: Calcium Carbide Residue and Rice Husk Ash

“…Moreover, while the increase of total porosity is beneficial for the structural and thermal efficiency of stabilized CEBs (Nshimiyimana et al 2020a), the WAP should decrease to improve the durability. This would turn into the decrease of capillary and total water absorption.…”

“…The durability of earthen materials is also commonly related to the compressive strength, mainly the ratio between the wet (Rcwet) and dry (Rcdry) strength. This ratio, defined as the coefficient of water strength (CWS=Rcwet/Rcdry), evolved in the range of 0.4-0.6 for CEBs stabilized with CCR and CCR:RHA (Nshimiyimana et al 2020a). The CWS of CEBs should reach at least 0.5 to be considered durable, according to standards XP P13-901 (AFNor 2001) and ARS 675:1996(CDI&CRATerre 1998.…”

“…In the present study, the CCR was mixed with RHA (rice husk ash), an agricultural by-product, for the stabilization of CEBs. These alternative binders were previously reported to undergo microstructural interactions with earthen materials which improved the physico-mechanical and hygrothermal properties of CEBs (Nshimiyimana, et al 2020a, Moussa et al 2019Nshimiyimana, et al 2019).…”

Thermal Performance Assessment of Walls Made of Three Types of Sustainable Concrete Blocks by Means of FEM and Validated through an Extensive Measurement Campaign

“…The main objective of this research is to determine the thermal properties of walls made of three types of blocks, by means of FEM simulations [42]. These results were compared to those obtained from experimental tests [34], in order to validate the numerical model.…”

Measurements of Thermal Conductivity of LWC Cement Composites Using Simplified Laboratory Scale Method

“…The accuracy of measurement in the use of different techniques for evaluating the thermal conductivity of cement compo-sites is being discussed by scientists. [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. It should be noted that several factors affect the thermal conductivity of concrete: the moisture content, temperature, density, porosity and adsorptivity of aggregate, and the properties of cementitious material are influential factors on the thermal conductivity of concrete [ 29 , 30 , 31 , 32 , 33 ].…”