Applications of Statistical Model in Proportioning of Concrete Block to Minimum Cost

Abstract

Abatract

The purpose of this study is to apply the statistical design of experiment in the field of civil engineering. The
advantages of using statistical experimental design are the reduction of the number of samples, shorten the experimental period and save cost of the experiment. The results obtained from statistical analysis have more reliable than the traditional method. This study used the statistical experimental design to find the mix proportion of concrete block that conform the TIS 58-2533 standard
at the lowest possible production cost as the case study of the research. In each year, demand of concrete block is increasing throughout the country. Since there are no standard mix proportion for concrete block, commonly sold concrete blocks in the market do not possess properties as required in the standard. Statistical methodology is applied to predict compressive strength
and calculated optimum mix proportions for concrete block. From test results, it was shown that the using of factorial design and central composite design were suitable for the optimization of concrete block. The simulated model can be satisfactorily used to predict compressive strength of concrete block in the test program. Four optimum mix proportions have been found. For concrete
block which uses Chipped stone as raw material, suggested mix proportion was 1 : 3 : 8 : 4 [cement : coarse sand : crushed dust : Chipped stone] by weight for machine production (non-hydraulic type) and 1 : 3 : 10 : 5 [cement : coarse sand : crushed dust : Chipped stone] by weight for machine production (hydraulic type). For concrete block which does not use Chipped stone as raw material, suggested mix proportion was 1 : 2 : 10 [cement : coarse sand : crushed dust] by weight for machine production (nonhydraulic type) and 1 : 3 : 13 [cement : coarse sand : crushed dust] by weight for machine production (hydraulic type). All suggested mix proportions require less production cost than normally used mix proportions in the market. It can be concluded that the production cost does not necessarily increase in order to produce a standard concrete block.