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Durable concrete experiences a long service life in most natural environments without deterioration. One of the important factors that influence the durability of concrete is curing. This paper represents a comprehensive investigation to study the effect of method and duration of curing on concrete durability. The techniques of curing used in this study encompass the majority of methods commonly encountered on site. The methods of curing were freshwater, wet burlap, plastic film, liquid membrane and air (no curing). The study considered different durations of curing of 3, 7, 14, 21 and 28 days. Concrete specimens were exposed to various conditions of deterioration: sulphate attack, cycles of wetting and drying, temperature changes, high temperature, fire and corrosion of reinforcing steel. Compression, tensile strength, weight and corrosion of steel were then monitored. Each of these parameters is utilized to evaluate the durability performance. Durability performance is defined as the ratio between a monitored parameter, under one of the aforementioned conditions of curing and deterioration factors, and the counterpart parameter of a standard reference specimen. A corresponding standard reference specimen was cured for 28 days in freshwater and subjected to the same deterioration condition. The study demonstrates that the method and the duration of curing heavily affect the durability performance. For the same method of curing the increase in the duration of curing increases the durability of concrete. The effect of the various curing methods on the increase of the durability of concrete for the same duration can be put into the following hierarchy: air (no curing), liquid membrane, plastic film, wet burlap and finally freshwater. Due to the tremendous impact of curing on the durability of concrete, quality control for proper field curing is of the utmost importance.

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Geotechnical engineers are faced with challenges in selecting safe and economic solutions for the foundations of light structures resting on deep layers of soft clay. Changing the bottom of foundation shape into shell-shaped footings is a solution to avoid using deep foundations or other costly soil improvement schemes. This paper introduces different foundation bottom shapes that resemble the footing stress distribution over the underlying soft soils in an effort to minimize its effect. Elliptical, trapezoidal and inverted folded footings have been used as an alternative to the conventional flat shallow footings. The purpose of the current study is to present the optimal shape of the foundations, which achieves soil stress reduction, settlements, and consequently lower footing thickness and reinforcements.

Foundations on expansive soils are of great interest to geotechnical engineers. Piles foundations are used in expansive soils to resist the induced heave. Many factors can affect the pile heave in expansive soil. These factors include the pile length, diameter, and pile loading. The depth of active zone and depth of wetting can also affect the pile and surrounding soil heave. A numerical model of a single straight shaft pile constructed in an expansive soil is presented herein. The numerical study concerning pile and soil properties is set to clarify their effect on pile heave. The finite element software, ADINA is used to model the pile and surrounding soil domain and to compute the pile heave. The model is exposed to inundation with various depths of wettings, where net pile and free field heave are computed. The results show that pile length significantly affects the pile heave, while pile diameter has no noticeable effect on pile heave neither has the pile loading. Tracking of the pile movement shows that it begins to settle immediately after decreasing the depth of wetting, returning approximately to its initial state due to loading at zero depth of wetting.