The Experimengtal Research Of Detects And Assessments Of Structural Entity Concrete Strength

Based on the guiding principles, including “detects are separated fromassessments and the assessments are strengthened, the measurements are perfectedand the processes are controlled”. To further strengthen the supervision andmanagement of construction quality, many institutions carried out monographicstudy, the application of engineering pilot and the extensive practical investigations.This experiment launched exploration and research on this aspect in Harbin, Hainan,Zhejiang, Beijing and other places under the same standards.Due to the shaping way, size and curing conditions (temperature and humidity)of the sample cured in standard condition is obviously different from the actualstructural members.“The strength of sample cured in standard condition "actually isa kind of “strength of materials”, rather than “structural strength”, so it can’t exactlyrepresents the actual quality condition of the concrete of structure. Therefore,people’s attention on the concrete strength of entity structure is increasing; thisstrength is one of the important reference indicators to the acceptance ofconstruction quality, strengthening identification and the analysis and assessment ofaccidents. However, the majority of construction site used only a single method ofmeasuring strength to detect the strength of structural concrete, and usually gettingdifferent conclusions when using different methods, which not well adapted to therequirements of the acceptance standard for construction quality. Especially,research on the detection and assessment of the strength of mineral admixtureconcrete was less. Scientific and reliable assessment of the structural entity concretestrength is great significance to perfect the acceptance theory of engineering quality.To this end, the experiment studied four types of concrete, including C30, C40, C50and C60with mineral admixture, analyzed the relationships of the strength ofspecimen cured in standard condition, the strength of specimen cured in samecondition, and the presumption strength got respectively by using Rebound Methodand Core Drilling Method; Meanwhile, analyzed the growth of various strengthtypes of concrete with equivalent age.Experiments show that there is similar effects of fly ash and slag to concretestrength development; At the equivalent age of28d (maturity of600),"the strengthof specimens cured in same condition","rebound strength of Structural Concrete"and "the strength of structural core samples" of admixture concrete did not reach thestrength of specimens cured in standard condition of28d; About admixture concrete,"the strength of specimen cured in same condition" could represented "the strengthof structural core sample" to carry out the detects of structural entity concrete strength; Also showed in this experiment, the strength of core samples with adiameter of50mm,75mm,100mm basically kept same.Meanwhile, various types of detection strength of admixture concrete had alogarithmic growth trend with the change of curing age, and in order to achieve therequired standards of testing the strength of ordinary concrete, the detect age of thestrength of structural entity admixture concrete should be appropriate extend; Or,with the same detect age of ordinary concrete strength test, we should reduce thedetect standards of admixture concrete strength test. Through the comprehensiveanalysis of the different test results due to geographical differences, Provide thebasis for the newly revised national standard <Code for acceptance of engineeringconstruction quality of concrete structures>(GB50204-2002).