Abstract
In this study, clayey soils are characterized as backfill and potential fusible raw materials for engineering. Geotechnical tests (particle size distribution, Atterberg limits, densities) and chemico-mineralogical analyses (X-ray fluorescence, X-ray diffraction and Fourier transform infrared) were carried out on samples collected from field in the locality of Boulgou (North Cameroon) followed by the determination of mechanical properties of fired bricks (850–1200 °C). The excavations carried out have revealed a thick layer of clayey soils (~ 2 to 2.5 m) over a sandy layer. This clay formation presents some stratifications with limited influence variation in terms of mineralogy. Mean grain size distribution is dominated by sand (62–80%), clay (12–25%) and silt (6–9%). It corresponds to silty–clayey soils regarding their methylene blue values (3.3–5.6), with low plastic (13–22%) to high plastic (33%) characteristics. They are classified by USCS as clayey sand/silty clay, while one sample is a poorly graded sand (SP). Clay minerals observed are kaolinite (6–12%), montmorillonite (2–6%) and illite (8–10%). Those parameters associated with their fine nature and high compressibility make them suitable engineering applications for backfill material and barriers. From chemical analyses, relatively high contents in alkali and alkaline earth elements (~ 4 to 6%) to be used as potential fusible raw materials for fired bricks or gres ceramics were revealed. Bricks characteristics are varied: linear shrinkage (0.3 to 9%), bulk density (1.8 to 2.3 g/cm3), water absorption (19.7 to 1.3%) and flexural strength (0.3 to 17.4 MPa). Overall, the requirement for fired brick (< 20%) is met up by the water absorption values. As from 1050 °C, these soils are made suitable for brick-making with good characteristics (metallic sound, good cohesion and flexural strength).
Highlights
The use of clayey soils as support materials, backfill or raw material by engineers cannot be done without prior characterization
Many researchers are focusing their works on clayey soils in engineering applications such as geopolymers for road and building materials [3], ceramic application for fired bricks and porcelains [4,5,6,7] and materials for backfill and core of earth fill dams [2, 8,9,10,11]
With regard to the thickness of the reserve clayey materials (2 to 3.5 m) and the interest focused on their global exploitation, a composite sample was obtained from an equitable gramme of clayey and sandy clayey layers in each well dug
Summary
The use of clayey soils as support materials, backfill or raw material by engineers cannot be done without prior characterization. In North Cameroon, clayey soils at Boulgou are extracted by the local population for pottery, plastering walls of houses and the production of construction materials (adobes and fired bricks using clamp kilns). These soils are extensively present in the locality, noticed by the cracks left beside when they are dried out. This study deals with the chemico-mineralogical and geotechnical characteristics of materials issued from the alteration of the geological massif of Boulgou (Northern Cameroon) for appropriated firing products and other potential valorizations in engineering application
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