Efeito do uso de resíduos do caulim e granito na regressão de resistência de argamassas.

Abstract

The motive of this work was the increase of industrial waste products. The byproducts of the kaolin and granite processing companies have caused a great environment impact and became a matter of concern among environmentalists. The aim of this study is to investigate the incorporation of kaolin and concrete waste, both with crystalline silica, in mortar. This mortar must have attributes, good enough to oppose the strength regression phenomenon. Initially was established the physical, chemical and mineral characteristics of the waste products, using the test results of several analysis: laser granulometry, x-ray diffraction, chemical, thermal, differential and gravimetric. The test samples, used for the experience, were divided in four groups: 1- cement and sand; 2- cement, sand and granite waste; 3- cement, sand and kaolin waste; 4-cement sand and granite and kaolin waste. The replacement of waste by sand was in the order of 50% and the waste/binder ratio of 0,40. For each group were prepared three test samples, moulded in a cylindrical shape, with dimensions 50mm x 100 mm, cured for 24 hours and placed in the oven for seven days at the following temperatures: 30°C, 100°C, 120°C, 180°C, 230°C, 300°C, 350°C and 400°C. After unmoulding the test samples, strength to compression and loss of body mass was evaluated. The data analysis showed that the compressing strength decreased when temperature rose from 180° C to 230°C and increased, again, above 230°C. The exception was sample n° 2 (cement, sand and kaolin waste), where the strength decreased from 180°C, and increased again from 350 °C. It can be concluded that the use of kaolin and concrete waste will depend on the temperature the mortar will be used. For exemple between 180°C and 230°C it is advisable to use the kaolin waste. Above 300°C use the granite one. For temperatures below 120°C it is not convenient to use either waste. The granite waste mortar was more efficient, as to the compressive strength, at temperatures.