In this study, an experimental investigation was done to study the behaviour of Normal Strength Concrete (NSC) and High Strength Concrete (HSC) Plain beams under torsion with the concrete mix of M40 and M100. No mineral admixtures are used to obtain the required strength of concrete. Eight NSC beams and eight HSC beams whose width was varying with 75 mm, 100 mm, and 150 mm; depth varying as 75 mm, 100 mm, 150 mm and 200 mm; and span of the beams varying 600 mm, 800 mm and 1200 mm were casted and cured to stud the effect of torsion. The principle aim of this study was to understand the torsional behaviour of the NSC and HSC beams for rotation, cracking, size effect and torsional strength. A standard torsional loading method was used for conducting the testing of beams. The results obtained were compared with different theories and code equations. It was observed that the torsional strength of the beam increases with the increase in strength of concrete. HSC beams have higher torsional strength than the NSC beams which has the same amount of reinforcement.

Construction delay in projects is a common manifestation in the construction industry. Delay in construction will lead to a bad relationship between the parties involved and will also lead to an increase in the allocated completion time. Delay in the ongoing project might result in the loss of the money, time and other facilities by the client and cause a lot of financial damage to the contractor due to its investment in the purchase of equipment, construction materials and the hire of skilled workers. Delay in construction is a common problem that occurs mostly due to the unforeseen problems during the design & construction stages which often lead to delays in the completion of the project. Oman’s construction industry is one of the most important industries for the country’s economic development and growth. In this study, analysis of some available literature was conducted, and a questionnaire survey was floated among contractors, consultants, clients, project managers, and engineers involved in construction projects. All the collected responses were evaluated by using SPSS. The results of the study identified a total of 60 causes of delay out of which three factors have a “High” significance level for construction delays. These factors of “High” significance were associated with “Client related issues only” in which the initial design was altered by the client, delaying in deciding by the client and, scope change by the client. Majority of the delay (84 %) was observed to be lying in the range of 1‑2 years. This study also recognized the effect and minimization of regular delay and delay resulted due to Covid-19. Minimizing construction delay criteria can be managed by having a proper control system in the project time and funds