ARU, CoET researchers invent anti-building cracks `proof`

BabuK · 2011-04-15T12:21:59+00:00

Firms and local communities undertaking construction works along the countrys coastal part where there is expansive clay can now sigh with relief after researchers from Ardhi University and College of Engineering and Technology (CoET) identified a new technology capable of improving the engineering properties of the soil. Dr Charles Lucian, who is a Geotechnics lecturer at Ardhi University told The Guardian on Monday that researchers from ARU and CoET developed the new geotechnical technology mixing clay with lime after observing that many buildings in these areas often become affected by expansive clay soil that normally swell and result into house damage. He said this problem is mostly abundant in Kibaha and Chalinze, Coast Region. Lucian said the swell pressure of 56o kPa in these areas indicate that the tested clay soil has a very high swell-ability in its natural state. Also moisture change, geology of the site, clay mineral as well as water were also identified as the main factors that cause building cracks in these areas. Dr Lucian said that the research was carried out by him in collaboration with and Dr Pancras Bujulu whereby they investigated the potential and effectiveness of soil stabilisation for improvement of the geotechnical properties of expensive soils at the Kibaha-Chalinze belt in Coast region. The research established that improper treatment of the expansive clay soils at the belt has caused widespread structural defects mainly in form of cracks in many buildings and pavements constructed in the area. This is mainly attributed to the localised internal stresses and non-uniform movements caused by swelling or shrinking of the expensive soils when they absorb water or dry up, respectively, he noted. Due to this obstacle, it is recommended that contractors use this new formula to create suitable grounds when constructing building. Take expansive clay soils, mix it with lime, and then wait for four hours, then take the soil obtained from the combination and mix it with cement to increase the rate of strength developmentthe process is known as two stage stabilization, he explained. We recommend them to use this formula because the results of this study have indicated that lime and lime-cement stabilisation can greatly improve engineering properties of expansive soils thereby change them into non-swelling and suitable ground or materials for construction purposes, he said. Also two-stage stabilization of plastic soils produces relatively higher strength than both lime-and cement stabilisation when treated separately, he added. Apart from that addition of cement to a lime-modified sample increases the rate and extent of strength development, he said. He said during the research, the results of the granulometric analysis indicated that the sampled soil is constituted of 29 per cent clay, 11 per cent silt, 55 per cent sand and 5 per cent gravel. SOURCE: THE GUARDIAN

Thread starter BabuK
Start date Apr 15, 2011

BabuK

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ARU, CoET researchers invent anti-building cracks `proof`

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