Substituição parcial do cimento portland por cinzas de Bambu (Bambusa Vulgaris)

Abstract

The partial replacement of Portland cement for industrial waste or materials of natural origin with renewable source is a way that has already been used to minimize the environmental impacts generated during its manufacture, such as CO2 emission, high energy expenditure and exploitation of the limestone deposits. The partial replacement of this binder can further improve certain properties of concrete and mortars and reduce the cost of their production. In this context, bamboo appears as a material with potential to use its ashes in partial replacement to the Portland cement, because it’s a natural material with renewable source and fast growth. Therefore, the objective of this paper is to evaluate the use of bamboo stem ashes (Bambusa Vulgaris) as partial replacement of Portland cement. For that, bamboo stem ashes were produced at three calcination temperatures: 500°C, 600°C and 700°C. The ashes produced at 600ºC obtained a performance index with Portland cement at 28 days higher than that established by NBR 12653 (ABNT, 2014). It was evaluated the hydration of the Portland cement partially substituted by this ash, in proportions of 0, 6, 10 and 14% and it was verified the decrease of the concentration of calcium hydroxide, being more expressive with the incorporation of 10% of ashes. Mortars with the same replacement proportions were evaluated in the fresh and hardened state. The consistency in the fresh state remained constant, while the compressive strength, in the hardened state, increased between 10 and 15% with the addition of the ashes. Therefore, it was concluded that the partial replacement of the Portland cement by bamboo stem ashes calcined at 600ºC presented benefits to the studied samples, characteristic of pozzolanic materials.