Relationship between the compressive strength of silica fume mortar applied to the substratum and the one obtained in standardized cylindrical test specimens

Resumo

Compressive strength values obtained from normalized tests are adopted in the use of silica fume mortar as reinforcement material, which are not usually good parameters to represent the compressive strength of mortar after having been thrown to the substratum. Each mortar portion launched to the substratum in a reinforcement procedure is submitted to a thickening process given as function of the energy of collisions of the mortar against the substratum, leading to differences in the compressive strength values observed in different points of the reinforcement extent, which reflects on the overall strength of the reinforcement taken as a whole defining a new load capacity for the reinforced structural element. A mortar plate with silica fume addition and with dimensions similar to a reinforced pillar face was executed in order to verify the real behavior of a reinforcement mortar. Some prismatic samples were extracted from the mortar plate and submitted to compression tests, from which an average compressive strength was obtained. When that average compressive strength is compared to the average compressive strength obtained from cylindrical test specimens molded using the same mortar material utilized in the mortar plate, it is observed that the average compressive strength determined from the mortar plate results presented a reduction of 35% in this particular case.