Publication details
Aggregate volcanic rocks potential risk for durability of concrete structure?(one of significant factors of structure crisis management)
| Authors | |
|---|---|
| Year of publication | 2007 |
| Type | Article in Proceedings |
| Conference | 11th Euroseminar on Microscopy Applied to Building Materials, Porto, 5-9. 6.2007 - CD ROM, |
| MU Faculty or unit | |
| Citation | |
| Field | Geology and mineralogy |
| Keywords | basalt - concrete - asphalt - degradation - petrography - aggregate |
| Description | The paper is focused on risk elimination related with application of basalt aggregates in asphaltic concrete production and application. Properties of asphaltic concrete closely relate to mineral composition of an aggregate, in studied case alkali basalts. Alkali basalts content in their mineral composition unlike calc-alkali basalts beside plagioclases, olivine and pyroxene and volcanic glass foids as well. Negative impact of alkali basalts secondary minerals (zeolites, clay minerals and products of volcanic glass devitrification) which starts their formation already in final stages of alkali basalts solidification on degradation of quality of asphaltic concrete is proved by case study on pumped storage power plant. There was observed bulging of surface of asphaltic concrete sealant layer on upper storage lake after 10 years of lifetime. They are discussed the results of microstructure study of aggregates, mineral associations, crystallization time sequence and mutual relations between individual minerals. Basic method of study was optical microscopy supported by micro-chemical study of selected mineral groups (EDX) and identification of mineral species by X-ray. The complex study has proved essential role of zeolites in the process of big pores and cavern formation in the watertight dense graded asphalt concrete layer. The initial reaction between minerals as chemical reagents of aggregate and asphalt starts already during the primary production of asphaltic concrete mixture. The releasing of water molecules from zeolite structure leads to formation of primary micro-pores. The water included in micro-pores and micro-cracks between aggregates and matrix during the winter times periodically freezes and increases its volume. They are formed first bigger pores and cracks spreading inward the layer. The process of water pumping in plant is periodically (every day) repeated so pores are exposed to temperature variations and continual water addition. |
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