LAUSR

The complex impregnation of a multifilament yarn by a cementitious matrix leads to a difficult prediction of the mechanical behaviour of textile reinforced concrete and its less spread use than steel‐reinforced concrete. To solve this problem, several models were established but they are not based on direct observations of the embedded yarn or quantification of its impregnation. In order to improve those models, a double resin impregnation process followed by confocal microscopy was set up, after pullout test was performed on each sample. Several parameters were then computed from the obtained images, which enables to quantify the impregnation of the yarn for each sample and to compare it with the pullout mechanical results. The number of fully impregnated filaments is found to be the crucial point to explain the pullout maximum load. The type of failure is also defined using those same parameters, computed along the embedded length, and it was found that the shape of the extracted volume of yarn is cylindrical and so the failure of the filaments is not telescopic. A pre‐existing model was then improved, considering all those conclusions obtained by microscopic observations, and a good match between the numerical and the experimental results was found.