Quality of Concrete of Recent Development Projects in Libya

Authors: Mohamed .S .Alazhari, Milad. M. Al Shebani

Abstract:

Numerous concrete structures projects are currently running in Libya as part of a US$50 billion government funding. The quality of concrete used in 20 different construction projects were assessed based mainly on the concrete compressive strength achieved. The projects are scattered all over the country and are at various levels of completeness. For most of these projects, the concrete compressive strength was obtained from test results of a 150mm standard cube mold. Statistical analysis of collected concrete compressive strengths reveals that the data in general followed a normal distribution pattern. The study covers comparison and assessment of 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 [1]. 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 (
) and is found to be (1.82 to 11.04), indicating that the range is ±3σ. International construction companies working in Libya follow different assessment criteria for concrete compressive strength in lieu of national unified procedure. The study reveals that assessments of concrete quality 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.

Keywords: Acceptance criteria, Concrete, Compressive strength, quality control

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1330163

References:

[1] ACI Committee 214, 1988. Simplified Version of the Recommended Practice for Evaluation of Strength Test Results of Concrete 214.3R-88, Reapproved 1997). American Concrete Institute, Detroit, U.S.A.
[2] A. M. Neville, Properties of concrete, Pitman Books Limited, 1982.
[3] ACI Committee 318, 2002. Building Code Requirement for Reinforced Concrete (ACI 318-02) and Commentary ACI Committee 318.
[4] Kausay, T. K. Simon, 2006. Acceptance of concrete compressive strength.
[5] CP 65. Evaluating Low Strength Test Results of Concrete, (Colorado 65-01), U.S.A.
[6] ACI E702, March 6 2007. Acceptance of Concrete Test Results.
[7] Ashraf. R. A. Mohamed, "Assessment of the current acceptance criteria for concrete compressive strength", Alexandria Engineering Journal, Vol. 43, No. 1, January 2004
[8] M. S. Alazhari, "Evaluation and Acceptance Criteria of Concrete Compressive Strength in Liby Engineering-Alfatah University
[9] BS 5328, "Concrete," British Standard Institution, England, 1993.
[10] John. H. Bungey, The Testing of Concrete in Structures, Surrey University Press, 1982.