No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

Carbon-black nanoparticles (CBN) have been incorporated into cement-based materials for improvement of mechanical or self-sensing properties. There is no previous research focused on the microstructural evaluation of effects of CBN on both parameters. In this work, mortars containing different CBN contents were produced, cured for 28 days, and subjected to electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Tests for determination of compressive strength, modulus of elasticity and piezoresistivity response were developed. SEM indicated that lower CBN contents refined the cementitious matrix, while higher contents increased the volume of voids. XRD and Raman spectroscopy indicated hydration improvements for CBN contents between 0.375% and 3%. The best mechanical improvements were provided by concentrations of CBN up to 3%. CBN contents of 5% and 6% provided the best sensing properties. The optimal concentration was found to be 5% of CBN, since it provided excellent piezoresistivity, without significant mechanical properties loss.

The dregs is a residue from the cellulose production, and finding new ways to use it would be interesting to reduce environmental impacts. This study aimed at incorporating it into mortar mixture ratios to replace the hydrated lime. Different proportions of cement, sand and dregs were evaluated using the Simplex-Lattice method of experimental design, and it was analyzed water absorption coefficient, compressive strength and flexural strength. The model adjustment was made with seven points plus three axial points and in terms of pseudo-components. A linear model was adjusted for the first characteristic, and a quadratic model for the second and third characteristics. Larger rates of capillary suction and smaller resistance values were noticed with a larger amount of dregs. This experimental design proved feasible, allowing the obtainment of mixture ratios from pre-determined values of water absorption coefficient and resistance, and making more objective the addition of dregs to mortar mixtures.