1 The importance of concrete testing
(1) In the process of testing concrete, through the systematic and quantitative analysis and evaluation of concrete quality, the performance indicators of concrete can be fully grasped, and then provide a scientific and effective basis for the specific construction use and maintenance of concrete, and enhance the rationality and applicability of concrete applications in actual construction.
(2) Through the effective detection of concrete, it can promote the concrete mix ratio to be more scientific and reasonable, which is conducive to reducing the cost input in engineering construction, and then improving the cost management level of engineering projects.
(3) Through scientific and effective concrete quality testing, it can effectively prevent the occurrence of engineering accidents and ensure the high-quality completion of engineering construction. In the process of project completion acceptance, by testing the quality indicators of concrete and other building materials, the overall project quality level can be scientifically and reasonably evaluated.
2 Problems in the concrete inspection process
2.1 The specimen itself factors
(1) There is a difference in the size of the specimen. In the process of concrete testing, the reasons for the gap between the measured size and the nominal size of the specimen mainly include: (1) the quality of the mold is relatively poor or the deformation difference is relatively large, and the inspector does not carry out the calibration work according to the requirements of the relevant standard specifications; (2) the number of times the use of the unstable standard mold is too much, and the surface time cannot be effectively controlled or the surface is not scraped, resulting in concave and convex surface problems.
(2) The pressure bearing surface of the specimen is not perpendicular to the adjacent surface. This situation is mainly due to the lack of good control over the quality of the tryout assembly, so it is necessary to effectively manage the quality of the tryout and its assembly.
(3) The flatness of the pressure surface of the test piece is not up to standard. (1) Because the uniformity of the vibrating operation in the process of specimen forming is not enough, or the brushing operation of the mold is not timely, or the mold disassembly time cannot be effectively controlled, it will cause the problem of missing shuttle angle of the specimen. (2) Failure to effectively control the slump of concrete or the amount of induced admixture will lead to a lot of bubbles on the surface of the specimen.
2.2 Factors at the time of specimen sampling or production
(1) In reality, the sampling time must be determined according to the specific conditions of concrete mixing, and the concrete of good quality mixed out of the mixture must be sampled, not random or random sampling, otherwise the sampling work is not representative, and the concrete quality situation cannot be accurately presented. (2) Individual construction enterprises in order to get more benefits. There is often a problem of shoddy or fake real. (3) The accuracy of the metering equipment is poor. Many construction companies do not determine the accuracy of the metering equipment in order to save trouble, making it a decoration and not being used effectively. (4) In the production of the sample to cope with business, because the on-site construction personnel are busy with work, or in the night of concrete pouring construction, so there are often unprofessional people instead of its production of specimens, resulting in the quality of the specimen is difficult to meet the standard. (5) In the process of making the specimen, the coarse aggregate used is more, which reduces its compressive strength, so it is necessary to strictly control the amount of coarse aggregate used in the production process of the specimen to ensure the rationality of the amount of coarse aggregate used.
2.3 Factors in the inspection and maintenance of concrete
Timely maintenance work was not carried out in accordance with standard specifications after the concrete specimen was made. At that time, after the test piece was made, it must be placed in an environment with a temperature of 20±5 °C and a humidity of 95% overnight, and then put it in an environment with a temperature of 20±2 °C and a humidity greater than 95% for 28 days before the compressive strength of the concrete can be tested. However, many construction enterprises do not have good maintenance conditions and try to save trouble, intentionally extend the time to send samples, resulting in substandard maintenance conditions after the specimen disassembly, which greatly reduces the accuracy of the test piece strength test results.
Some testing departments only attach importance to economic interests and ignore the stability and humidity requirements of the relevant norms for maintenance, which also makes it difficult to obtain accurate results for the testing of specimen strength.
3 Implement the relevant measures for solving the detection problem and optimizing the detection
3.1 Strengthen the importance of concrete testing
In order to achieve continuous optimization of concrete testing work, testing institutions must first pay attention to the importance of concrete testing work, mainly because the concept and focus of testing are the fundamental factors that lead to testing problems. Relevant enterprises should strengthen the training of supervisors and guide supervisors to understand the importance of supervision work. In this process, through the evaluation of the application of testing technology, the corresponding reward and punishment measures are formulated to standardize the work of the testing personnel.
3.2 Determine the aspects of the testing items
In the process of strength testing of concrete materials, it is necessary to strictly follow the requirements of the relevant specifications and standards, for example, when cementing concrete is prepared, it is necessary to test its stability, strength, condensation time and fineness. For the coarse aggregate in the concrete, it is necessary to detect its particle gradation, density, mud content, mud content and needle plate particle content to ensure that it cannot exceed the concrete crushing index. In addition, it is also necessary to carry out the relevant firmness test on the newly used loose texture aggregate, and to do the activity test on the active aggregate.
3.3 Pay attention to the sampling operation in the concrete inspection work
In their daily work, the inspectors should strictly verify the measuring instruments, pay attention to the maintenance and repair of the relevant instruments, and avoid errors in the use of the measuring instruments. At the same time, we must pay attention to the randomness of the sampling operation and strictly control the sampling time and method. After concrete mixing, segregation will inevitably occur during transportation, and the staff should continuously mix the concrete evenly with a shovel to ensure the uniformity of the concrete.
3.4 Strengthen the control of ambient temperature and humidity
When testing the strength of concrete, temperature and humidity are the two main factors affecting the test results, so the temperature and humidity of the test environment must be strictly controlled according to the relevant regulations and standards, so as to improve the work efficiency of the test personnel and the accuracy of the test results. For example, if the relevant specifications stipulate that the temperature around the specimen molding process should be ensured in the range of 20 °C ± 2 °C, and the humidity should be more than 50%, the actual testing work must be carried out in accordance with this requirement. The inspector must strictly implement the testing work in accordance with the temperature and humidity standards specified in the relevant specifications and standards to ensure that the test results obtained have good reference value. Therefore, the inspector should strengthen the control of the ambient temperature and humidity before starting the testing work, ensure that it is within the reasonable range of the regulations, and then implement the specific testing work, thereby improving the rationality and effectiveness of the test results.
4 Conclusion
All in all, in order to ensure the high quality of engineering construction and save costs, the strength testing of concrete is very necessary. Therefore, in the actual construction, we must increase the importance of concrete strength testing, actively take effective measures to solve problems in the testing work, ensure the accuracy and effectiveness of the test results, provide a valuable reference for improving the quality of engineering construction, and promote the better and faster development of engineering construction.