Abstract
The construction sector in Saudi Arabia has grown substantially in the past three decades. It is expected that the demand on concrete will increase by 10% by 2019. The compressive strength is considered to be the most important property and it is used as an indicator to check the quality of concrete and to judge compliance with specifications. The main aim of this research is to contribute to the quality evaluation of concrete construction in the region of Hail Saudi Arabia. In this study, a statistical compressive strength, using 180 test samples after 7 and 28 days taken from different concrete constructions in the city of Hail, is analyzed using the normal distribution and control chart. For each mix, a comparison of the average value of compressive strength, standard deviations and coefficient of variation (C.V.) is made. In addition a control chart of each mix is plotted with the upper and lower limit. The results showed that, apart from two mixes, the quality ranged from good to excellent with a coefficient of variance ranging from 4.13 % to 14.74 %. The results of compressive strength are within the upper and lower limits and no single test falls below the specified strength for all mixes. For all mixes the required average strength is 3.0 standard deviations above the specified strength, resulting in over-designed and uneconomical mixes. (c) 2017 The Authors. Published by IASE.