Estudo do efeito da microcelulose sobre o desempenho de materiais compósitos de matriz cimentícia

Abstract

Nanotechnology has been one of the ways of promoting better performance in materials used in construction. Materials in nano and micro scale offer new possibilities for cementitious composites with better mechanical performance. The reduced sizes allow interactions between cellulose and cement system, contributing potential way to combat the microcracks and increase strength of concrete. The research methodology followed a script with three phases. As the first phase, consisting of the characterization of crystalline microcellulose (MCC), where the following tests were made: infrared spectroscopy (FTIR), wherein the MCC was subjected to alkaline degradation in order to compare their state without degradation, electron microscopy (SEM) for morphological, differential scanning calorimetry (DSC) analysis of relative property to phase changes with no weight change, thermogravimetric analysis (TGA) - mass loss analysis in relation to temperature and image capture. In the second stage the MCC was inserted into distilled water, and the mixture agitated at different times in order to analyze the behavior in relation to their dispersion, and after that were brought to the electron microscope to image capture and morphological analysis. In the third phase tests were carried out with prepared mortar containing different dosages of MCC in relation to the cement mass in its fresh and hardened state, being performed consistency index test, compressive strength, flexural strength, absorption, and finally, collected samples in the hardened state and taken to the SEM to it morphologically characterized. It was observed from the results that the MCC presents an irregular and rough morphological structure. TGA tests it was seen that the loss of MCC initial mass starts from 60 ° C which occurs through water evaporation, and that from 350 ° C to MCC presents decomposition rate, making this one aspect positive for its application in regions with high temperatures. In consistency index test it was observed that as it increases the MCC rates in cementitious composites there is a progressive decay of consistency ( mm ) . Regarding compressive strength was observed increased resistance at all ages , with the insertion MCC in 0.2% addition. Regarding flexural strength there is a progressive increase to the percentage of 0.6 % of MCC , which is what stopped the peak strength of 7.67 MPa