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Gypseous soil which is used is taken from Tikrit city in Salah Aldeen government and specially from Tikrit University from a depth (1.5-2)m, It’s type is sandy gravely with a small percentage of silt and clay while the percentage of gypsum is (34-36)%, The tests on soil is standard proctor compaction, direct shear, collapsibility and California bearing ratio. The number of samples is (70). The effect of adding concrete waste (2, 4, 6 and 8%) and waste of Asphalt mixture (2, 4, 6 and 8) % on dry soil, as well as the effect of mixture of the optimum percentages of both additions on the properties of gypseous soil, is the aim of the study. Adding concrete waste at optimum percentage (6)% causes an increase maximum dry density at (16)% and a decrease in optimum moisture content at (5)%. Whereas adding concrete mixture waste in its optimum percentage (2)% caused a decrease in maximum dry density values with an increase of optimum moisture content, and when adding mixture of optimum percentage of waste, an increase happened in the M.D.D.(14)% with a decrease in O.M.C. at (4)%. Adding the optimum percentage (8) % for both. Value of cohesion increases (100)% when adding concrete waste with an increase in the angle of internal friction (14)% and a decrease in collapsibility in a percentage of (90)%, while adding waste of asphalt mixture shows an increase in cohesion value (112)% with a decrease in the angle of internal friction (2)%and a decrease in collapsibility in a percentage of (90)%, when adding mixture of optimum percentages the value of cohesion increase (108)% with an increase in angle of internal friction (14)%and a decrease in collapsibility in a percentage of (91)%. Values of California Bearing Ratio in dry and soaked condition increases (49)% when adding (8)% of concrete wastes which is the optimum percentage, while adding waste of asphalt mixture causes a decrease in the value of C.B.R. and the optimum percentage is (2)% , but adding optimum percentages mixture of them causes an increase in values of (52)% in dry condition and (53)% in soaked condition.

The aim of this study was to investigate the size effect of reversible and irreversible components of volume change behaviour of highly expansive and moderately expansive soils experimentally. The soil deformations of small-, large- and extra-large-scale samples were measured during wetting and drying cycles. Accurate dial gauges were used for measuring vertical deformation, and digital image correlation techniques were adopted for measuring horizontal desiccation cracks using a microcrack measuring device. Wetting and drying cycles that rely on seasonal moisture content variations in the subsoils were performed on an extra-large field model of a highly expansive soil. Results were compared with those of standard swelling tests to estimate vertical swelling and shrinkage-induced soil deformations that are expected in practice under public infrastructures. The field model, which represents reconstituted soil samples, presented a free swelling of 3·61% in the first cycle. In the second cycle, reversible free swelling increased by 7·68% over the first cycle given the irreversible components of shrinkage caused by lateral desiccation cracks. Irreversible deformations were observed during the drying processes through a network of microcracks and macrocracks. The reversible and irreversible deformations during the first drying process were 45·7% and 54·3%, respectively.

This paper investigates the capacity of a single laterally loaded pile in single- and multi-layered sandy soils under dry, unsaturated and saturated conditions for a wide range of void ratios. Two Linear ariable Differential Transformers (LVDT) were employed to measure lateral displacements. For unsaturated tests, on one layer and two layered sandy soils, suction was controlled using the hanging column technique. Two different suction levels were applied to the soils. The results demonstrated that, the capacity of a single laterally loaded pile in single- and multi-layered sandy soils, under unsaturated conditions, were greater than those in dry and saturated conditions for loose, medium and dense states. Comparison between experimental data for unsaturated tests and several proposed mathematical expressions in the literature for calculating the capacity of a single laterally loaded pile in sandy soils showed a significantly good fit between measured and predicted values of the capacity of the piles where Bishop’s stress is used in the expressions instead of effective stress, confirming the importance of inclusion of suction and degree of saturation in mathematical models when unsaturated conditions of soils were investigated.

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