Sugar cane bagasse is a residue of the sugar-alcohol industry, and its main destination is represented by burning boilers for power generation. The bagasse cogeneration of power produces a sugar cane bagasse ash (SCBA) residue that does not have a useful destination. Ashes are commonly studied as pozzolan in Portland cement production. International Standards indicate the use of pozzolan with up to 50% substitution. In the present work, we investigate the use of SCBA as an addition in Portland cement. For this purpose, Portland cement was prepared by substituting cement with 0, 10, 20, and 30% processed SCBA in volume. The ashes were processed by re-burning and grinding and were then characterized by scanning electron microscopy, Xray diffraction, laser granulometry, X-ray fluorescence spectrometry, the Chapelle method, and pozollanic activity. To evaluate the cement with substitution, we used the mortar recommended by NBR 7215. The mechanical properties of the cements with replacement were analysed through tests of the compressive strength and flexural strength of mortars. The results appear interesting and support the possible use of SCBA in the production of cement from the aspect of mechanical properties evaluated.

The manufacture of Portland cement used in the production of concrete emits large amounts of CO2into the atmosphere, contributing to the increase of the greenhouse effect. The environmental impact generated by the mineral exploration activity is a problem of easy verification, especially in open pit mines. The present work evaluated the possibility of using iron ore tailing as an addition to the partial replacement of the cement in mortars. The iron ore tailings were processed by drying in oven (48h at 105oC) and milling in a planetary mill (10min at 300RPM), obtaining medium grain size of 14,13 μm. For the characterization, laser granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal and thermogravimetric analysis (DTA / TGA) were performed. The sample is composed predominantly by quartz, hematite, goethite and gibbsite. After the characterization, the waste was used in the preparation of test specimens, with 10, 20 and 30% weight substitution of the cement. The composites were submitted to compression tests, with ages of 3, 7 and 28 days, using a strength rate of 0,25MPa/s. The mortars with 10, 20 and 30% of substitution presented resistance of 41.65, 36.26 and 31.64 MPa, being able to be characterized as category of Portland cement of resistance 40, 32 and 25 respectively. Considering the reduction of cement in the mortars produced, the results of compressive strength were relevant for the substitutions. The cements produced with the substitutions according to the Brazilian standards under the mechanical aspect can be classified as Portland cement.

Pozzolans are materials that when milled are able to react with the cement, forming compounds with binder properties. Seeking to reduce costs and improve Portland cement performance, the cement industry has used mineral additions such as pozzolans, partially replacing clinker in Portland cement. Sericitic Phyllite is a metamorphic rock, considered sterile by iron mining. It is extracted from the pit to enable the extraction of iron ore and is disposed in sterile piles, representing an environmental liability. The present work evaluated the possibility of the Sericitic Phyllite acquires pozzolanic properties from thermal treatment, to be used as mineral addition in the partial substitution of Portland cement in mortars. The material was processed by milling in its natural moisture of 8% using a high performance planetary mill, and calcination in an electric resistance furnace at different temperatures (350, 550 and 850oC) for thirty minutes each. It was characterized by laser granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal and thermogravimetric analysis (DTA/TGA). After characterization, specimens were prepared with 25% substitution by weight of the Portland cement by the Sericitic Phyllite. The calcined material in 350, 550 and 850oC reached, respectively, 70%, 76% and 82% of the resistance of the control mortar. The results indicate the feasibility of using the Sericitic Phyllite as mineral addition in Portland cements as the mortars with the calcined material in all temperatures reached 32MPa.