Marl crumbling decrease using geopolymer mixtures: lessons from experimental tests in the vicinity of Fez, Morocco

: Despite its abundance in many regions of the planet, the marl’s use in practical issues engender many problems, in relation to its components’ quality, its physical and chemical characteristics and its valorization costs. The crumbling is among its major critical aspects that affect its engineering behavior, its handcraft and other socio-economic uses. This paper apprehends the physical and chemical properties of the Miocene marl in Fez vicinity (Morocco). They are investigated to measure their changes and see how they affect the marl’s geotechnical characteristics. Mixed with cellulose and pozzolan at different concentration degrees, the marl samples were exposed to extreme temperatures, observed in the laboratory and interpreted in terms of characteristics reliable to crumbling risk reducing as cohesion and materials’ resistance. By adding the cellulose and pozzolan to the raw marl at different percentages (1%, 5%), (2%, 10%), (3%, 15%), (4%, 20%), (5%,25%), we have tested its characteristics using various techniques and analyses. We mainly used X-ray diffraction, X-ray fluorescence and SEM techniques This study apprehends the possible production of innovative materials based on marl mixtures. It emphasizes the valorization of the Miocene marls in the region of Fez (Morocco) but its aims are larger as the results may be applied for marl worldwide. The main goal is to identify the best thresholds that are suited to improve the mixed marls’ physico -chemical properties and therefore reduce risks of crumbling in marl. The results are concluding as chemical analyses show a slight variation of major chemical elements in the samples’ contents. We note that after adding pozzolan and cellulose to marl, the Fe2O3 and SiO2 increase and favors neoformation of clays. New illite and metakaolinite appear. The difference is important when we compare results between characteristics of the raw marl and those of the mixed marls, in particular at temperatures of 900 °C and 1000 °C. The mineralogical analyzes have shown the appearance of well crystallized hematite. In mixed marl, these results were confirmed by the electron microscope analysis. The results converge to confirm the positive impact of geopolymer mixtures as they contribute to decrease the risks of marl crumbling as its cohesion and resistance become intense. These new marl’s characteristics are innovator and show a new degree of the material’ transformation. They favor the marl’s advantageous exploitation in economic and industrial activities. Even locally experimented, the importance of the obtained results may be worldwide. These results show a perfect crystallization of minerals such as quartz, hematite and the transformation of illite and kaolinite into mullite and metakaolinite. From these curves, it is observed that there is an increase in the intensities of the minerals with the addition of pozzolan and cellulose. Quartz (SiO 2 ), mullite (M) and metakaoilinte (MK) and a small peak for CaO and Al 2 O 3 are observed. These phases usually occur mainly in cement, ceramics and glass-ceramic materials produced from incinerated waste and glass powder (Asquini et al., 2008). The increments in the cullet content in the samples showed a marked reduction of peaks in CaO and Al 2 O 3 , while the presence of amorphous phases can be observed through the analysis of the raw marl sample.