The Optimal Proportion in Construction Quantity Analysis for Reinforced Concrete Structures of Detached Housing Projects

Reinforced concrete structures (RC structures) have been widely adopted for a long time, particularly in the widespread constructions of single detached houses. Nevertheless, quantity surveying (QS) to find out a proportion of RC usage per a unit of structural components such as concrete, reinforced steel, and formwork is still limited and inappropriately determined, particularly with only the use of existing numerical data to describe the statistical results in term of possible numerical ranges. The objective of this research is to study in detail an overview of the proportion values by assessing the proportion values in construction quantity analysis for RC structures of detached housing projects under construction. Hence, the researchers perform data collection, verification, and investigation, and classify the results into five groups as follows: (1) an average proportion of the lean concrete volume to a construction area versus that of the compacted sand volume to a construction area, (2) an average percent proportion of the concrete-beam volume to the total concrete volume versus that of the concrete-slab volume to the total concrete volume, (3) an average proportion of the concrete volume to a construction area, (4) an average proportion of the reinforced steel weight to the concrete volume and that of the reinforced steel weight to a construction area, (5) an average proportion of a formwork usage to the concrete volume versus that of a formwork usage to a construction area. Presumably, only a single mean value is insufficient for further consideration. Hence, using mean value ± standard deviation (SD) value together with a boxplot diagram can increase a level of confidence by displaying in graphic the data distribution through their quartiles and interquartile range (IQR) sections, covering more than 50% level of confidence based on basic statistical theory. And the value can be further applied more appropriately.