Physico-thermal, mechanical, and toxicity properties of stabilised interlocking compressed earth blocks made with produced water from oilfields

Abstract

Inefficient wastewater management has been recognised as a major contributor to global water crises due to its potential for contaminating ecological resources. This study investigates the physico-thermal, mechanical, and leachate properties of stabilised interlocking compressed earth blocks (CEBs) produced from oil wastewater and soils from two major oilfields (Nimr and Marmoul) in Oman. An experimental testing programme was conducted to investigate compressive strength, thermal conductivity, and water absorption rate, including leachability properties of the CEBs. The X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), and scanning electron microscope (SEM) analyses showed similar mineralogical composition and micro-structural properties of the soil samples. The findings from this study revealed that CEBs from both oil fields have shown good compressive strength values of about 4.5–7.3 MPa and 4.0–8.1 MPa at 7-and 28-curing days, respectively. The produced CEBs satisfy the Omani standard for blocks for both non-loadbearing and loadbearing masonry walls. The thermal conductivity properties of both Nimr (0.927 W/m.K) and Marmoul (1.001 W/m.K) CEBs agreed with the typical masonry concrete blocks (0.7–1.3 W/m.K) used in building construction. This study's water absorption rates were found to be slow, indicating that most of the pores found in the blocks showed moderate accessibility to water. Thus, the water absorption rates of the CEBs from both Marmoul (16%) and Nimr (17%) oilfields were moderate compared to similar studies found in the literature. Also, to determine the sustainable application of the produced CEBs, a leaching test revealed a low concentration of all the selected heavy metals, except chromium (3.73–3.14 mg/L), which was slightly high but yet was found below the United States Environmental Protection Agency (US EPA) standard of 5.0 mg/L for hazardous waste material, thereby posing low environmental threat to soil and aquatic systems.