Review of the quality control of concrete reinforced with steel fibers according to the spanish structural concrete code EHE 08

This paper analyze the differences between the quality control of conventional concrete (CC) and that of steel fiber-reinforced concrete (SFRC), according to Annex 14 of the Spanish Structural Concrete Code EHE 08 "Recommendations for the use of concrete reinforced with fibers" Annex 14 of the Code EHE 08 "Recommendations for the use of concrete reinforced with fibers" specifies the particularities of the steel fiber-reinforced concrete (SFRC) quality control regarding the conventional concrete (CC) one. The quality control of the SFRC is mainly the sum of the CC quality control and an specific part consisting of controlling the fiber types used and the amount of them added to the concrete. In the case that the fibers have also an structural function, it is necessary to control the remain flexural strength of the concrete, as specified below. UNE-EN 14651 regulation specifies the procedure to control the remaining flexural strength. This involves defining the remaining flexural strength fR,1,m and fR,3,m of three pieces for each mix at 28 days age. For each mix, it is necessary to define also the amount of fiber used according to UNE 83512-1 o UNE 83512-2. The Code EHE 08 also allows the use of other procedures to perform the control of the remaining flexural strength of the SFRC under specific conditions. Regarding the control of the concrete consistency, it is recommended that when in the Abrams cone test are obtained values lower than 9 cm, other alternative control procedures must be used, such as the Webe consistometer according to EN 12350-3 or the inverted cone method according to UNE 83503. When the fibers have a structural function, it is not allowed to apply the indirect method to control the concrete strength. The Code only gives particular specifications for this type of concrete when 100 per 100 method to control the concrete strength is chosen. It indicates that the control should be performed over two mixes per lot, controlling both the residual strength and the fiber content. In the case that the fiber content on a mix is less than 10% of the stipulated value, the control of the residual flexural strength should be extended to all mixes on which samples are taken to determine the compression strength. The analysis of the results and the estimators to be used to obtain the characteristic values from the tests are the same as those indicated by the Code for compression strength. Finally, complementary tests can be carried out, using procedures to obtain the tenacity of concrete such as the double punch test (Barcelona test). The quality control of SFRC specified by the Annex 14 of the EHE Code is mainly dedicated to the case that the fibers have a structural function. It is based on adding the control of the residual flexural strength and of fiber content to the quality control specified for the CC