Dissolution calorimetry study of basalt fibers.

Basalt fibers and Basalt Fibers Reinforced Polymer (BFRP) bars are currently widely studied as alternative elements for reinforcement of concrete subjected to an aggressive media, especially to sea water, where conventional streel reinforcing elements are suffering intensive corrosion. Nevertheless not even the basalt based reinforcing elements are completely stable in a range of environment which may be attacking the concrete. The first step of a corrosion process of basalt fibers is their interaction with aggressive solution, which may result to a chemical reaction between fiber and a component of medium and consequent dissolution of fiber (and possibly followed by precipitation of a solid corrosion product). The present paper aims to characterize the initial – dissolution – step of interaction of basalt fibers with five types of solutions (from acid to alkaline) which are attacking basalt fibers in concrete by help of isothermal calorimetry. The obtained results proved that basalt fibers are reacting with acid, alkaline and salty solutions. The most intensive endothermic heat flow appears in all solutions (except water) after a few minutes; nevertheless certain measureable heat flow was generated for at least 6 hours of reaction. High pH of solution is responsible for higher (absorbed) total heat and longer reaction duration. This study will continue by attempt to characterize the reaction products by SEM and XRD, as well as to describe the reaction kinetics in a longer time scale than is covered by calorimetry. [ABSTRACT FROM AUTHOR]