CIMENTO ECOLÓGICO: SUBSTITUIÇÃO DE CINZAS DE BAGAÇO DE CANA-DE-AÇÚCAR DERIVADO DA INDÚSTRIA SUCROALCOOLEIRA

Abstract

With the accelerated growth and the high demand for more raw materials, the civil construction industry has contributed to the lack of some natural resources. In the present work, we sought to study the behavior of cementitious matrices with sugarcane bagasse ash (SCBA) replacement to produce a more sustainable and ecological cement. The ashes to be used are a by-product of boilers in the sugar and alcohol industries in the cities of Quirinópolis (SF) and Santa Helena (CM), both in the state of Goiás, dried at 105ºC for 24 hours to remove moisture, sifted through a 150μm sieve and stored in plastic packaging for later use. In this study, an experimental program was adopted, in which pastes and mortars were produced with 0% (control), 25%, 30% and 35% replacement, of cement by CBCA. The ashes were characterized by X-ray fluorescence analysis (FRX), thermogravimetric analysis (TG/DTG), X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). The CBCA chemical composition identified the amount of silica, aluminum and iron oxides within the standard recommended for class C pozzolana, however, a high loss of mass on ignition (LOI) was also identified. An amorphous halo was also identified in the ash from the city of Santa Helena (CBCA-CM), which is not present in the ash from Quirinópolis (CBCA-SF), therefore, the first ash has better characteristics as a pozzolanic material. Paste samples were used for TG/DTG and DRX analysis to identify the hydrates formed at 28 and 90 days of curing. The TG/DTG results showed that at 28 days the pastes with replacement had all the calcium hydroxide (portlandite) consumed and at 90 days the portlandite peaks reappeared in the sample with 25% of CBCA-CM, 25% and 30% of CBCA-SF, results corroborated by the XRD analysis. The mortar mixtures were characterized in fresh and hardened states, through workability, compressive strength, flexural tensile strength, void ratio and immersion absorption tests. The best mechanical results were observed in the samples with 25% of CBCA-CM at 90 and 180 days, being above the results of the control mortar. Thus, the pozzolanic behavior of samples with ash achieved better results in long curing.