WITHDRAWN: In-situ compressive strength assessment of concrete in under-construction residential buildings at Gaindakot municipality

Abstract

Abstract Concrete is the most used construction material in modern era. A general evaluation about concrete’s quality can be obtained by determining its compressive strength. In Nepal a few research have been carried out to ensure the in-situ quality of concrete. The objective of this study was to access the compressive strength of concrete produced at site, their ingredient’s proportion and compare if they comply with NBC of Nepal. 90 cubical specimens from 30 houses in 10 wards at Gaindakot Municipality were collected purposively and tested for compressive strength value along with the proportion of cement, sand, aggregate and water. After analyzing cubes from 30 houses, the mean compressive strength was found to be23.928 N/mm2. Similarly80% of houses constructed at site prepared and placed concrete having compressive strength value more than 20 N/mm2, complying NBC of Nepal. ANOVA analysis showed that there was no significant difference in compressive strength means among houses of 10 wards but there was higher standard deviation and wider range within houses of same wards. 73.33% of sampled houses produced concrete maintaining water-cement ratio of 0.4 to 0.6 but no consistency in use of sand and aggregates revealing inconsistent and uncontrolled concrete production process. Control chart showed that more than 15% of measured compressive strength of concrete lied outside the control limit point.