Influence of the variation of the content of the sand in the formation of the air bubbles concretes with air-entraining addictive and in the its carbonation

Antonio P. Peruzzi1 , Joseph S. Barbar2 , Antonio C. Santos 3 , Daniel S. França 4 and Lucas N. Almeida5

1,2,3Professor Doctor, Faculty of Civil Engineering, Universidade Federal de Uberlandia, Av. Joao Naves de Avila, 2121 – Santa Monica, Uberlandia, Brazil.
4 Civil Engineering student, Universidade Federal de Uberlandia, Av. Joao Naves de Avila, 2121 – Santa Monica, Uberlandia, Brazil.
5 Civil Engineering graduate, Universidade Federal de Uberlandia, Av. Joao Naves de Avila, 2121 – Santa Monica, Uberlandia, Brazil.

ABSTRACT
Air-entraining additives are used in civil construction, for an action of elimination of the freeze/thaw cycle, in self supporting concrete and to change its density, to obtain a more economical structure or better thermal performance. Indented characteristics depend on the composition of the raw materials, which in turn depend on the type, quantity and distribution of solids and voids. Granulometric distribution of the sand, have great influence in the formation of the air-entrained bubbles, interfering in the quantity, size and distribution. In this study, were prepared samples using basaltic crushed stone, Portland cement, air-entraining additive (0.5% of the cement mass) with different levels of quartz sand, understand their influence on bubble formation. Thus, 3 types of concretes were studied: A1(1.0:1.0:2.0:0.58); A1.5(1.0:1.5:2.0:0.58); A2.5(1.0:2.5:2.0:0.58) and A3(1.0:3.0:2.0:0.58) (cement:sand:crushedstone:w/c) and casted in cylindrical samples of each of the respective types, cured for 7 days and tested by water absorption, voids index and compressive tests. Amount, size, characteristics of the bubbles entrained into the concretes, were analyzed by optical microscopy. The connectivity of the bubbles formed was studied by exposing the samples in a saturated chamber with CO2 for 7, 14 and 28 days by the mensuration of the depth of the front of carbonation. The study showed that the variation of the sand quantity used has a great influence on the characteristics of the bubbles formed and, there is a limit that, if exceeded, increases the possibility of its coalescence occurring enabling it’s connection, leading to risks related to durability of the concrete.

Key words: Concrete; Air-entrained; Optical microscopy; Microbubbles; Aggregate variation

Cite this article:
Peruzzi, A.P., Barbar, J.S. , Santos, A.C. , França, D.S. & Almeida, L.N. (2019). Influence of the variation of the content of the sand in the formation of the air bubbles concretes with air-entraining addictive and in the its carbonation. European International Journal of Science and Technology, 8(10), 1-10.