Efectos de los sulfatos de sodio y magnesio sobre las características físicas del concreto y sus agregados

Abstract

Stone aggregates are granular materials used in the construction of resistant elements. Samples of ½ ”and ¾” coarse aggregates from the “La Libertad” quarry of the Municipality of Samacá in the department of Boyacá were subjected to physical-mechanical tests to evaluate their resistance and quality, according to the standards proposed by the National Institute of Roads (INVIAS), the results indicate that these aggregates have good quality conditions for use in concrete. The representative aggregate fragments of the materials produced were observed, initially with a magnifying glass and stereoscope to determine aspects such as selection, color and shape. Subsequently, thin sections were observed under a polarized light microscope to analyze their mineralogical and textural characteristics, with special emphasis on the analysis of susceptibility to the development of pathological processes that may affect their performance in their use as concrete components. Once these observations were made, the fragments were immersed in sodium and magnesium sulfate solutions to verify what the effects are on the aggregates and on the concrete when exposed to these types of sulfates and thus observe the changes that they are presented in each one. When performing the immersion, results were evident such as: the loss of mass was 2,149 g with magnesium sulfate and 7,492 g with sodium sulfate compared to its initial weight in the test of crystallization of salts of aggregates in concrete , a decrease of 1.99% in the ½ ”aggregate and 1.82% in the ¾” aggregate in the sulfate solidity test carried out on the aggregates, in addition, the fragmentation and detachment of the aggregates was observed due to the crystallization of salts within the structure of the pores, causing a change in their volumes, fracturing the concrete.