Assessment of Concrete Quality in Libya

Abstract

Abstract The quality of concrete used in current and past 20 construction projects were examined based mainly on the concrete compressive strength achieved. The projects are different in nature and are at various levels of completeness. In Libya, concrete compressive strength was usually obtained from test results of a 150 mm standard cube mold. Data collected from all 20 projects showed that the 28-day concrete compressive strength follow in general Normal Distribution pattern. The study dealt with concrete quality aspects such as: quality control, strength range, data standard deviation, data scatter, and ratio of minimum strength to design strength. Site quality control for these projects ranged from very good to poor according to ACI214 criteria. The ranges (Rg) of the strength (max. strength – min. strength) divided by average strength are from 34% to 160%. Data scatter is measured as the range (Rg) divided by standard deviation (σ) and is found to be (1.82 to 11.04), indicating that the range is ±3σ. In lieu of national unified procedure, international construction companies working in Libya are free to use the assessment criteria for concrete compressive strength that suit them. Therefore, the study reveals that concrete quality assessments conducted by these construction companies usually meet their adopted (internal) standards, but sometimes fail to meet internationally known standard requirements. The assessment of concrete presented in this paper is based on ACI, British standards and proposed Libyan concrete strength assessment criteria.