Avaliação das propriedades físicas, mecânicas e residuais de concretos celulares produzidos com areia natural e de RCD

Abstract

In this work, the influence of Xanthan Gum on the quality of pre-formed foam was evaluated, as well as the use of Construction and Demolition Waste (RCD) for the production of cellular concrete. Thus, the quality of the foam was evaluated through stabilization, density, drainage and microstructure tests. Afterwards, cellular concrete mixtures were produced with and without xanthan gum and RCD, with target densities of 800kg/m3, 1000kg/m3 and 1200kg/m3. The concretes were evaluated in the fresh and hardened state. In the fresh state, cellular concretes were evaluated using specific mass. In the hardened state, physical indices were evaluated, such as: specific mass, thermal conductivity, compression behavior and flexural tensile strength. Compressive behavior and flexural tensile strength were also evaluated at three residual points of cellular concrete when subjected to temperatures of 300oC, 600oC and 900oC. The use of xanthan gum proved to be important in the stability of the foam, enabling delayed drainage and promoting smaller and more circular pores in cellular concrete. In the fresh state, cellular concrete presented acceptable characteristics, managing to achieve the desired characteristics for the studied densities of 800kg/m3, 1000kg/m3 and 1200kg/m3. In the hardened state, the physical indices of cellular concrete showed statistically equal results. In relation to thermal conductivity, all cellular concretes presented values much lower than those specified by standards, and all mixtures are efficient in this regard. Compressive strength increased with the use of xanthan gum. The total replacement of natural sand by RCD impaired the mechanical compression and flexural tensile strength of all cellular concretes studied. This loss is possibly due to the maximum size of the recycled aggregate used. The residual resistance after burning cellular concrete was impaired, and as the firing temperature was increased, the mechanical resistance obtained was lower. Finally, the stiffness of cellular concrete was strongly affected, reducing as the firing temperature of cellular concrete increased. Keywords: Cellular concrete. Construction and demolition waste. Residual mechanical strength.