This paper presents quality control charts techniques usually applied in quality control of compressive cement strength. Nonlinear regression model useful for the prediction of compressive cement strength at 28 days was proposed. Combining the prediction and quality control tools, a PI (Proportional Integral) controller useful for the regulation of 28 days compressive cement strength around a target (39 Mpa) was constructed. Results of the one-year prediction of quarterly compressive cement strength aligned with the values of the historical data obtained from a leading Cement Company in Nigeria for the years, 2011-2015.
The use of agricultural waste as pozzolan is widely accepted, because of several improvements possible in sandcrete composites and the overall economy. However, eggshell ash is a pozzolan that appears to have significant potential for the production of high strength and high performance sandcrete block. Although available information on eggshell ash sandcrete is limited, this research attempt to investigate and presents an experimental study on the effect of replacing cement with eggshell ash (ESA) in sandcrete block production. Results of the compressive strength test of sandcrete block containing ESA at varying replacement levels were discussed and compared with those obtained with the control (100% Portland cement sandcrete block). The total partial replacement was considered in the range of 0% (control specimen) to 40% by weight in steps of 5%. The combination for each replacement level apart from 0% are as follows: 95% cement and 5% ESA, 90% cement and 10% ESA, 85% cement and 15% ESA, 80% cement and 20% ESA, 75% cement and 25% ESA, 70% cement and 30% ESA, 65% cement and 35% ESA, 60% cement and 40% ESA. Sandcrete blocks specimen were produced and tested at 7, 14, 21 and 28 days of curing respectively to appreciate the strength development of each replacement value. It was observed that the strength decrease with increase in percentage replacement. But the best results were obtained at 30% replacement with a value of compressive strength of 4.7N/mm2 of the 28day strength of that of the control at 28days, which met the standard requirement in Nigerian building code.
This study investigated effect of cement production activities and seasons on the concentration of air pollutants such as Total Suspended Particle (TSP), Thoracic Particulates viz respairable and inhalable sizes (PM2.5 and PM10) and gaseous pollutants: Carbon monoxide (CO), Sulphur dioxide (SO2), Oxides of Nitrogen (NOx) and Hydrogen sulphide (H2S). The cement company is located in Ogun State, Nigeria between latitude 6Вє 54′ N вЂ“ 6Вє 55′ N and longitude 3Вє 12′ E вЂ“ 3Вє 12′ E вЂ“ 3Вє 13′ E; studied between July вЂ“ December, 2010. Sampling was carried out at Production plant (starting point), Administrative office (400 m), Ewekoro community (500 m), Cement mill (800 m), Ajobiewe community (1000 m) and Agbesi estate (1500 m). The samplers used were Stage gravimetric sampler (for suspended particulate matters), Tetra multi-gas monitor (CH4, CO and H2S), Multi gas meter, Land Duo (CO2, NO and NOx) and BW, Model 0539, gas alert (SO2). Data were analyzed using descriptive statistics and analysis of variance. Test of significance of the means was by the Least Significant Difference and Duncan Multiple Range test. Significant concentrations of TSP, PM10, PM2.5, SOx, NOx CO and H2S were observed in the vicinity of Cement Company. Higher concentration of PM was observed in the dry season than wet season. Cement production activities release air pollutants. There is need to reduce the rate of emission during cement production to the lowest minimal level by using air trapping devices.
The study was designed to investigate the the progress of Indian cements industry since 1991, in terms of its growth in installed capacity, production, exports, and value additions; In detail the research methodology used for the study that has focused on the past, present and the future performance of Indian Cement Industry (ICI) at the macro level and the Chettinadu Cement Corporation Limited (CCCL) at the micro level as a case firm. The study purely relies on secondary data. The secondary data were collected for a period of fifteen years (1991-92 to 2005-06) from the database maintained and made available by several organizations viz., Cement Manufacturers Association, Export Import Bank of India, Centre for Monitoring Indian Economy etc. for the purpose of effective periodical analysis. In order to know the progress of ICI, annual time series data for the six variables were studied for trend, cyclical variation and random variation, as seasonal variation was not observable in the annual data. The estimated trend equations were evaluated for their goodness of fit and predictive power and found valid to draw inferences. The values of the six variables were projected to the next five years. Estimated values were adjusted for the likely effects of cyclical variations (c) the reliability of predicted values were evaluated with the help of forecasting error. In the end of the study implications and conclusion were provided.