In this investigation, different natural by-products were used to modify the Particle Size Distribution (PSD) of a soil to evaluate their potential in Stabilized Rammed Earth (SRE) building. Three different mixes were manufactured: (i) a mix composed entirely of a clayey soil, (ii) a mix consisting of mining by-products and clayey soil and (iii) a mix entirely based on mining by-products. Unstabilized and stabilized samples of the mixes were manufactured using two cement dosages (2.5% and 5%), and the samples were tested for Unconfined Compressive Strength (UCS), soaked UCS, and wetting and drying tests. Mining by-products demonstrated significant potential in SRE building, as their addition to the clayey soil resulted in higher UCS values compared to the UCS obtained from clayey soil alone. Unstabilized samples lost their integrity during exposure to water. The inclusion of mining by-products also showed potential as, although the mixes did not fully meet the requirements for soaked UCS and the wetting and drying tests, the mix containing both mining by-products and clayey soil retained its integrity in water, unlike the samples composed solely of clayey soil. M3C5 successfully met the requirements for soaked UCS and the wetting and drying tests, further highlighting the great potential of mining by-products in SRE building.

Earthen materials has received a lot of attention as a sustainable building material over the past few decades because of its eco-friendliness. As consequence of this renewed interest, numerous works have been recently developed on earthen materials, mostly with a focus on their mechanical behaviour. Conversely, there is still a significant gap in the literature on the understanding of the fire behaviour of earthen materials. Only a handful of studies has dealt with this subject and a systematic analysis on the causes of thermal instabilities in earth materials at high temperatures is still missing from the literature. The role played by the mineralogy of the earth materials on these thermal instabilities is still poorly understood and it requires further investigation. To fill these gaps, the present study presents the results from both mineralogical and hygrothermal tests performed on earth samples, which were either left unstabilised and compacted at 50 MPa or stabilised with cement and compacted at the optimum standard Proctor. Interestingly, unstabilised earthen samples exhibited thermal instabilities when exposed to high temperatures. To investigate deeper into the mineralogical causes of such thermal instabilities, samples were either equalised at the ambient temperature of about 25 °C or exposed at the high temperature of 350 °C before being subjected to thermogravimetric and differential scanning calorimetry (TG-DSC) tests, Fourier Transform Infrared (FTIR) spectroscopy tests, isothermal adsorption-desorption tests, and nitrogen gas permeability tests. Results show that cement stabilisation induced the formation of fresh the calcium-silicate-hydrate (C-S-H) and calcium-aluminate-hydrate (C-A-H) gels while reducing the water adsorption capacity. Both effects have rendered the material less prone to thermal instabilities compared to the unstabilised material. The main mineralogical and moisture-related changes influencing thermal and fire behavior might not be well captured by traditional studies. Though lacking in information to perform a thorough study, they do provide initial indications of possible internal alterations within the materials.