**1. Introduction**

Sand contaminated with crude oil has become a major environmental concern worldwide. This problem poses threats to human health, the ecosystem, and the properties of the surrounding sand. Due to the prohibiting cost of the existing remediation methods, a more cost-effective way of utilising oil contaminated sand is warranted. Mixing oil contaminated sand with cement and using this mix as alternative construction material is considered an innovative approach to reduce its environmental impact.

There is growing public concern about the wide variety of toxic organic chemicals that are either deliberately or inadvertently being introduced into the environment.

Petroleum hydrocarbons are a common example of these chemicals because they frequently enter the environment in large volumes and in a variety of ways. Leakage from natural deposits is one way that crude oil affects the environment [1] and oil wastewater associated with the production of oil and gas is another source of oil contaminated sand [2–4]. Intentionally or accidentally, oil spill contamination impacts on the properties of the surrounding sand and changes its physical and chemical properties [2]. To minimise its effect on the environment, methods of remediation ranging from sand washing, bio-remediation, electro-kinetic sand remediation, and thermal desorption have been implemented, but are not considered to be cost effective [5]. One alternative method is using contaminated sand for engineering applications; indeed, some researchers have already investigated its use in that area and concluded that sand contaminated with oil can be used for road base materials or topping layers in parking areas [6–8]. However, the successful use of waste materials in concrete depends on the mechanical properties developed by the end product. While some studies investigated the effects of oil contamination on concrete, these studies only focused on heavy crude oil and engine oil [3, 9, 10] as well as hydrocarbons [10–12]. For instance, Almabrok et al. [13] investigated the effect that incorporated mineral oil has on the cement solidification process, and its consequent effect on the fresh and hardened properties of mortar. Almabrok et al. [14] further investigated oil solidification using a direct immobilisation method. Furthermore, the effect of kerosene impacted sand on the compressive strength of concrete in different conditions was investigated by Shahrabadi and Vafaei [15]. In this study, different percentages of kerosene (0, 0.5, 1, 2, 4, 6 and 8%, by weight of sand) was used to evaluate the effect of kerosene-soaked environment on compressive strength of concrete. They concluded that using contaminated sand adversely affects the compressive strength of concrete and hence, a reduction up to 27% in the concrete compressive strength occurred when samples with 2% of kerosene contamination were used. In a similar study by Attom et al. [16], the effect of 0.5, 1 and 1.5% of kerosene and diesel by dry weight of sand was investigated. They noted a reduction of up to 42% in the compressive strength as the level of contamination increased. Recently Shafiq et al. [17] investigated the effects of used engine oil (UEO) on the slump, compressive strength and oxygen permeability of normal and blended cement concrete. They concluded that engine oil caused variations in the compressive strength in the range of ±20% compared to the control mix. However, the UEO caused a reasonable reduction in total porosity and the coefficient of oxygen permeability of all concrete mixes compared to the control mix which can help this type of concrete achieve a high performance. Recently a study conducted by Abousnina et al. [18], the author investigated the effects of light crude oil contamination on the physical and mechanical properties of geopolymer cement mortar. The results showed that geopolymer mortar has the potential of utilising oil contaminated sand and reducing its environmental impact.

This shows the high potential of oil contaminated sand as sustainable material in building and construction. However, understanding the physical and mechanical properties of contaminated sand and its effect on produced mortar and concrete is very important in order to determine their end-use application [19]. Once achieved, this will potentially solve the issues of oil contamination in oil producing countries because the cost of this method will be cheaper compared to the existing remediation methods. Therefore, in this chapter the authors presented an extensive investigation to evaluate the effect that light crude oil has on the mechanical properties and microstructure of concrete. The succeeding sub-sections provide a better understating of

the main sources, properties, existing remediation methods, and the beneficial use of oil contaminated sand in engineering and construction.
