| Popis: |
The objective of this study was to evaluate, comparatively, the evolution of this degradation of three rock types, two granitoids and a microgabbro which, eventually, could be used as ballast, due to the proximity of the quarries to the design route of a railroad to be built between São Paulo and around Campinas, State of São Paulo, southeastern Brazil. They were tested for alterability in sodium sulfate and ethylene glycol solutions. Based on detailed petrographic analysis, Micro-Deval and Slake Durability Index tests were performed with and without conjugation to the referred alterability tests. The results obtained are punctual, valid and positive for the samples of the rock masses carefully selected and described, considering the different characteristics of the granitoids belonging to the Morungaba and Cantareira Complexes. In the case of basic rock, the microgabbro, should not be used as ballast in the studied tropical climate area, since the exposed fragments that make up the ballast are intensely affected by chemical weathering (notably reactions accelerated by water and temperature), which culminate in the decomposition of primary minerals and, consequently, in the faster physical-mechanical degradation of this rock. In practice, more frequent periodic maintenance and higher costs. |
