Mineral seal construction, manufacturing processes and geosynthetic sealing strip

A mineral seal construction, especially for sealing waste tips, stagnant industrial land or similar areas, includes two or more clay layers(2a,2b) separated from each other by intermediate layers(4) which ensure that the water content in each clay layer is independently controlled in both wet and dry conditions to maintain the clay in a soft, effective sealing condition. An alternative construction comprises at least one clay layer(2) and water storage layers(5) above and/or below it which ensure that the water content of the clay layer remains constant and gives a soft clay consistency for effective sealing. A claimed water and/or oil permeable, geosynthetic clay sealing strip comprises a carrier(1) and a cover(3) layer a swellable clay layer between them and the outer layers(1,3) are connected so that during swelling they remain together and transfer shear force from the cover into the carrier layer. The clay layer may comprise two clay layers(2a,2b) or two fleece and /or open cell foam layers containing clay separated by an anti-capillary layer(4). A process for continuous manufacture of the geosynthetic clay sealing strip involves covering a carrier layer(1) with powdered and/or granulated swellable clay(2a), covering with an anti-capillary layer(4), applying a further layer of clay(2b) and an outer cover layer(3). All layers(1,2a,4,2b,3) are then needled, sewn, knitted or welded together. An alternative geosynthetic clay sealing strip comprises a carrier and a cover layer with a swellable clay layer between swellable clay between them. One or more water storage layers are located above and below the clay layer, above, in or under the cover layer and/or under, in or above the carrier layer and all layers are connected together to retain integrity during swelling and transfer shear stress. In a process for manufacturing this alternative geosynthetic sealing strip a water storage layer is placed on a carrier layer, followed by a swellable clay layer, a second water storage layer and finally a cover layer. All layers are then connected as described. In a variation of this process a first water storage layer is placed on the carrier, followed by two layers of powdered or granular clay separated by an anti-capillary preventing layer, a further water storage layer and cover layer.