Stabilization of high plasticity clay with lime and gypsum (Ankara, Turkey)

Abstract

Clayey soils might lead to swelling, settlement and strength issues when considered as foundation or fill material. The use of additives to stabilize soils has been a major concern in the improvement of engineering characteristics. Upper Pliocene-aged clays cause various geotechnical problems in the residential area of Ankara. The aim of this study is to investigate the effect of lime, gypsum and lime with gypsum mixtures on the swell percent, swell pressure and unconfined compression strength of highly plastic clays in the Batikent region to specify an appropriate mixture ratio for soil stabilization. The optimum water content and maximum dry unit weight of clay were determined using standard compaction tests. Lime, gypsum and lime with gypsum mixtures were re-compacted in order to evaluate their effect on the swell percent, swell pressure and unconfined compression strength over curing time. Swell percent and swell pressure reduce with increasing additive percent over time, while the strength increases. The lowest improvement ratio is determined for gypsum. The optimum mixture is concluded to be 6 % lime, which corresponds to a 99.55 % decrease for swell percent, 98.98 % decrease for swell pressure and 191.87 % increase for the unconfined compressive strength for 90 days.

Improving the Early Properties of Treated Soft Kaolin Clay with Palm Oil Fuel Ash and Gypsum

“…The maximum dry density increased from 1.59 gm/cm 3 for kaolin alone to 1.63 g/cm 3 and 1.62 g/cm 3 for K4G and K6G, respectively, as the gypsum absorbs more water during compaction, as shown in Figure 15; these results are in line with those presented by [32,35,68,69]. However, when adding up 5%, 10% and 15% of POFA with gypsum, the MDD continued to drop until reaching 1.465 g/cm 3 for K6GP15 as the lowest.…”

“…However, we should consider that the high amount of gypsum in the soil increases the internal sulphate attack [31]. Gypsum is one of the materials used as an alternative in chemical improvement techniques by many researchers [32,33]. It is also found that gypsum partially applied in soil enhanced its physical and chemical properties.…”

Swell and microstructural characteristics of high-plasticity clay blended with cement

“…Soil stabilisation involves the improvement of the engineering properties of weak soils mechanically, physically or by mixing with binders to achieve some predetermined objectives. The use of additives to stabilise soils has been a major concern in the improvement of engineering characteristics of problematic soils such as soils susceptible to swelling (Kilic et al 2016). Calciumbased hydraulic stabilising agents such as lime and cement are commonly used to chemically improve the engineering properties of highly plastic clays.…”

Earthen Plasters Stabilized through Sustainable Additives: An Experimental Campaign

“…The gypsum is not the result of a secondary sulfation reaction (such as ettringite) which is considered potentially harmful to concrete only if it is formed in the hardened material and not during the setting as in the case of the aluminous cement [103]. Once the gypsum has hardened, it does not dry out easily (temperatures close to 120 • C are required) and is poorly soluble (Henry and Stewart, 2012), a more stable behavior in environmental conditions could be achieved by the addition of a little % of lime (about 2.5%) as traditionally done in the alker technology [104,105]. Although CKD proved to be the best in terms of resistance to erosion, drilling resistance, waterproofing, and action against swelling clay minerals, therefore making the plaster more resistant toward imbibition and drying cycles, this additive is not compatible in terms of permeability to water vapor, which is excessively reduced.…”