Quality Control Concepts in the Manufacture of Masonry Blocks for Building Project Delivery

Abstract

This research work was undertaken to assess the application of quality control concepts in the production of masonry blocks for building projects in Imo State, Nigeria. The study was embarked upon in order to examine the different types of masonry blocks produced in the state, and to assess the level of quality control concepts applied in their production processes, using selected block industries in Owerri Municipality. The study also was aimed at finding out the educational qualifications of the workers at those block industries. The research was an attempt to search for answers to the problem of building and infrastructural collapse that has become rampant in Nigeria recently. Data for the research was collected through the views of the staff and management of the case study block industries and data analysis which was carried out by the use of percentages and frequency tables and chi-square statistical tool, revealed that the problem of low quality masonry blocks used in building projects were due to several latent factors like time lag between mixing and placing of mix into mould; mould of placing mix into mould before compaction; type of cement; and inappropriate sand-cement-water mixture ratio. These things were found to have great and decisive effects on the ultimate strength and quality of the building blocks. The research also revealed that poor mixing of cement, sand and water, lack of quality control measures and low quality sand were responsible for low quality blocks in many block producing small and medium scale industries. This situation is contributing to building and infrastructural collapse. The study therefore recommends that quality control concepts should be applied in the production of masonry blocks. The use of acceptance sampling tests for all the raw materials used in masonry block production and application of control-chart for work-in-process should be adopted. The pre-process, in- process, and post-process inspections and testings must be carried out for the production and standardization of high- quality building blocks before the products are made available to the customer. In the block industry, the quality control methods used for inspection and testing for quality control are screening or 100% inspection, sampling or lot by lot inspection and process inspection. The application of quality control in the block industry should cover the whole production process right from the raw material stage to the finished product. The control areas should start with the control of raw materials, in process control, control of finished products, visual control and physical control which has to do with quality control tests. Proper control measures in the manufacturing process should result in the following:  Decrease in reject rate and increase in product quality.  Reduction in price of products hence better value for money.  Increase in product yield which should make economic mass production possible.  Reduction in production and distribution/delivery cost.  Good reputation for the industry and improved.