Swelling characteristics of Madinah clays

Abstract

Six expansive clays from the city of Madinah, Saudi Arabia have been investigated. The expansive nature of these clays is due primarily to the presence of smectite. The basaltic lava around Madinah is considered to be the source of this mineral. Kaolinite and illite also present in these clays are thought to be derived by the alteration of smectite. Calcite occurs only in the 'white clayey silt' and in the 'upper brown clay'. Qualitative estimates using plasticity index and clay fraction data suggest 'low' to 'very high' swell potentials of these clays. Laboratory swell-consolidation tests indicate that for initial liquidity index in the range of -0.91 to +0.32, the percent swell for these clays is 1.02% to 13.2% and the swell pressure range is from 58 kPa to 770 kPa, the higher values of these two parameters being observed for grey-green clays with liquid limit less than 120% and particularly at low moisture contents. The swelling characteristics of expansive clays depends on numerous factors making the prediction of volume change and swell pressure difficult. This paper discusses the use of multi-variate analysis to aid the prediction of these parameters for the Madinah grey-green clays. The progressive lowering of the groundwater table in the Madinah area is likely to promote more severe desiccation of Madinah clays in the future. In view of the high swell potential of Madinah clays, there are important implications in relation to foundation design in Madinah.

Evaluation and Prediction of the Swelling Characteristics of Nigerian Black Clays

“…The values fall within the range of free swell percentages obtained byHossain et al (1997) for expansive Madinah city clays which have smectites as the dominant clay minerals. Only the free swell values for Biu clays are close to those obtained by…”

“…The liquid limits range from 63.5% to 65.6% and plasticity indices are greater than 30. The liquid limit is a parameter which is generally considered to have some bearing on the swelling characteristics of soils (Hossain et al, 1997). Linear shrinkage values are relatively high and range between 10.20% and 12.76%.…”

“…These two parameters are considered by El-Sohby and Mazen (1987) to be the most important parameters describing soil behaviour in the determination of swelling pressures. Hossain et al (1997) developed several regression equations relating swell percent and swelling pressure to initial dry unit weight, initial water content, clay content, liquidity index at start of test, liquid limit or plasticity index for Madinah clays. None of these equations incorporates a term to show the effect of physico-chemical factors on the swelling characteristics of soils.…”

Mineralogical composition and physical characteristics of marly soils from Heraklion Crete

“…Η έκταση της διόγκωσης εξαρτάται κυρίως από τα γεωλογικά χαρακτηριστικά και τις φυσικομηχανικές ιδιότητες τους όπως περιεχόμενο αργιλι κών ορυκτών, περιεχόμενη υγρασία, όρια Atterberg, αντοχή θλίψης κ.λπ. (Hossain et al, 1997, Shakoor και Sarman, 1997. Η συμπεριφορά διόγκωσης εδαφών πλούσιων σε αργιλικά ορυκτά έχει μελετηθεί εκτεταμένα στο παρελθόν.…”