Dissolution-precipitation reactions of silicate mineral fibers at alkaline pH

Carbonation Curing and Kinetics of Wood-Sodium Silicate Composites

“…At high carbonation pressure, the pH of SS rapidly reduces, with the formation of Na 2 CO 3 and SiO 2 , and reduced bonds and linkages occurs . In addition, CO 2 when dissolved in water under high pressure can form sodium bicarbonate (NaHCO 3 ) and silicic acid which can disrupt the network of sodium silicate, resulting in a low T onset value. , Upon post-curing at elevated temperatures of 105 °C, reactivation possibly occurred, and the final residual ash was higher with values from 77% to 88% in comparison to 67% to 83% residue for the samples post cured at 60 °C.…”

Reaction kinetics of basaltic elements in cementitious matrices: theoretical considerations

“…Temperature, basalt fibers composition and surface area, presence of aqueous elements (Ca, Mg, Fe, Al or Si in particular) or acidity/alkalinity of the environment belong among the most important ones. When pH reaches values higher than 9, which is typical for concrete or other cement-based materials, the dissolution of basalt take place due to silicate network hydrolysis [2].…”

“…In order to get valuable input data for the modelling procedure, it is highly recommended to arrange such a set of measurements that will be able to provide the mass loss time functions at different liquid/solid ratios of the reactants, specific surface of the basaltic elements or molarity of the solution. As showed by Ramaswamy et al [2], it is important perform a basalt fiber characterization to get knowledge about the precise mineralogical and/or phase composition, both qualitative and quantitative, and specific surface of the fibers which enables to calculate the mass loss for particular constituents of basalt (mainly for Si, Ca, Al, Fe or Mg).…”

“…Such properties make these fibers possible to be applied in various environments including the aggressive ones. Unlike steel, however, the alkaline nature of cement matrix might go along with some negatives resulting in partial fibers decomposition by the effects of OH-ions that break the siloxane bonds while releasing silicate into the solution [1,2]. Since these processes represent the essence of the fibers corrosion, the understanding and possibility of an accurate estimation of the dissolution rate is of a high importance as it can help to control a cementitious phases formation, to assess the durability or to predict changes of related material properties including the change rates.…”