Encountering weak fine-grained soil presents a significant challenge during highway construction. The conventional approach to address this challenge involves incorporating calcium-based stabilizers, particularly cement, for stabilization. However, despite its widespread use, the application of cement for soil stabilization has adverse environmental consequences. Accordingly, finding alternative methods to minimize cement usage has become a prominent area of research, from researchers worldwide. This study evaluates the effectiveness of utilizing discarded polyethylene terephthalate (PET) bottle shreds as soil reinforcement alongside lower cement contents. To this end, soil samples were mixed with varied contents of two grades of shredded PET. The ground PET pellets, which displayed diverse shapes, demonstrated properties resembling fibres. Compacted samples were subjected to CBR to determine optimum PET content. Strength, small-strain stiffness and durability of soils in original state, mixed with cement and PET were measured by a programme of CBR, wetting–drying cycles, and ultrasonic pulse experiments. Findings suggest a 28–91% increase in strength of soil upon its mixing with cement—PET shreds. Substituting cement with cement—PET shred led to a drop in accumulated loss of mass (ALM). In twelve cycles of wetting and drying, the small-strain stiffness initially decreased, but then stabilized at approximately the same value in the subsequent cycles. The porosity to binder ratio was adopted as an index for CBR, ALM and the maximum shear modulus. The latter was finally proposed as a measure for durability.

Construction work involves some of the most complex operational actions, where many activities require to be carried out at the same time and place. The nature of this type of work, subsequently, makes it an extremely hazardous environment for workers. By constructing sophisticated and intelligent safety systems to make construction work and sites safer, and bypasses any unforeseen costs caused by accidents that can occur during the construction work. To construct such systems, it is required to know the causes behind accidents. So that, to improve the overall safety performance, there is a need to investigate the causes of construction accidents and to evaluate the current safety systems used to give a picture of the weak points in systems currently adopted. The awareness of these things can be used in formulating safer working environments for construction work. This paper identifies the causes of the accident and evaluates the present safety systems in different construction projects in Northern Iraq. The study has been conducted by reviewing literature from articles and books, plus applied quantitative approaches to collect data by applying a questionnaire survey prepared for this study to collect data from the sites’ users. The results of the current study show that the overall evaluation of the safety system is in poor condition, also found that there are many causes behind accidents. The most severe cause is considering safety as a second priority, and the study classified the causes into, unsafe actions and unsafe conditions.