| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 101 === Ready-mixed concrete is the most widely used construction materials for construction projects, and the compressive strength test with cylindrical concrete specimens is an important subject for project acceptance criterion. In recent years, due to aggressive market competitions, it is not uncommon to see that construction tenders get the project with unreasonable low bidding prices. Hence, the changing of test specimens and malpractice between laboratories and construction companies are commonly seen in cylindrical concrete specimens examinations. Therefore, to implement effective concrete quality control is a very important issue.
In this study, we have conducted literature surveys about examination systems and inspection regulations of cylindrical concrete specimens, and established a questionnaire with three major subjects: inspection system, management of laboratory and inspection mechanism and acceptance criteria. Five professional groups including public construction bureau, engineering consultants, construction companies, ready-mixed concrete plants and laboratories are selected for the questionnaire survey. These survey data were then statically analyzed by Microsoft Excel to explore the correlation between the existing concrete quality and the acceptance criteria of compressive strength of cylindrical concrete specimens, and propose the relevant improvement measurements.
According to the results, for the inspection system, that fail to effectively implement the “random sampling process" is the main reason that test reports cannot fully reflect the quality of materials. Execution of "Random material sampling by the third party" is the first priority to improve.
For the laboratory management, that the occurance of false inspection reports issued by the laboratory is mainly due to the request by the ready-mix companies, and that "in order to avoid loss of customers" is the second. Hence, the primary suggestion is "to increase the number of un-notified auditing to laboratories ", and the most favorable answer is to set up "a payment system with independent bidding to pay the testing fee of concrete specimens.
For the inspection mechanism and acceptability criteria part, the inspecting frequency of concrete specimen ought to be required once per 100 m3 per group, the number of samples be (1+3) and the age of compressive strength experimental be 28 days. The “acceptance” and “unacceptance” standards for compressive strength test of concrete specimens of the Taipei City Government Bureau are relatively practical and feasible.
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