The Sampling Methods In Concrete Quality Engineering

The merits and drawbacks of the sampling procedures that are specified in the present standard of "the inspection and assessment standard of concrete strength" (GBJ107 —87) are studied in this paper, according to the actuality of the development of sampling methods in concrete quality engineering. A lot of data about compression strength of concrete are acquired on the spot for profound study. By means of these records, the quality characteristic of concrete is obtained. This study is a fundamental work and is scare now. This study in this paper can make up for the blank of this aspect and contribute to the research of the problems about concrete strength.The lot fraction defective is the key to establish the sampling method. But it is not studied before. By means of these records this paper acquires, the quality characteristic of concrete is first obtained and the approximate lognormal distribution of lot fraction defective is presented. Through the new probability density evolution method, the more precise information about the distribution of lot fraction defective is calculated. This contributes to the scientific establishment of sampling method.The sampling procedure for inspection by attributes is putted forward in this paper. According to the shortage of adopting empirical law to setting the key parameters of the sampling procedure, a principle of minimizing the total sampling cost of producer is introduced to optimizing the producer's risk α and a principle of the balanced total risk between the producer and the user is first introduced in this paper to calculate the consumer's risk β in phrase for coordinating the benefit between the producers and the users. The sampling procedures for different concrete grades are established in this paper. At the same time the importance of structure is considered and different coordinated risks are introduced to setting the sampling procedures for taking into account of the importance of structure simply and scientifically.By means of numerical simulation method, the sampling procedures that are...