Specific features of determining concrete strength by stud driving method

Introduction. The method of determining concrete strength based on steel stud driving into concrete by firing has been used since the 1960s. At present, several institutions promote this method as an alternative to direct nondestructive testing methods (pullout test and shear angles) and propose to introduce it into the current standard GOST 22690-2015. Its availability and low cost compared to those of the existing standard methods are mentioned to substantiate this proposal.

Aim. In this work, domestic and foreign studies and normative documents regulating the considered test method are analyzed, and its standardization and the volume of additional research are evaluated.

Materials and methods. Theses from the mid-20th century to the present, normative documents (ASTM C803-02, BS 1881-207, DIN EN 14488-2), and instructions (Z-WP-534. Windsor Probe System, Driving method Hilti DX 450-SCT) were reviewed.

Results. Significant limitations for the application and the factors having the most profound influence on the accuracy of the method were identified: hardness, type, and fineness of the filler, variation of firing charge power, and indenter parameters (driven stud). These factors have no influence on the control methods recommended by the existing standards. Foreign standards stipulate the application of this test method as an indirect technique, requiring adjustments based on the testing results of standard samples or test cores extracted from structures; however, no data on its accuracy is provided.

Conclusion. Given the revealed limitations, it is premature to standardize the method. Further research is recommended. The statement about the significant availability and cheapness of the reviewed method relative to the standard regulated methods is unsubstantiated. 

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