Complementary analyses of concrete characteristics performed on cores taken from concrete pavements

Abstract

The basic assessment of cement concrete pavement condition is performed by a visual inspection, when the surface faults which are macroscopically distinguishable are documented. Detailed data on concrete condition require further tests performed on cores. Apart from common standard tests, such as layer thickness, compressive and tensile strength, resistance against water and chemical defrosting agents, other macroscopic and microscopic analyses have become useful. Some of the most important ones include petrographic assessment of aggregates (based on the fraction and type of rocks), quantification of cracks (expressed by e.g. cracking index or damage rating index), analyses of air void characteristics in concrete (expressed by e.g. spacing factor test), indication of type and extent of expansion reactions with the help of chemical reagents that visually mark the affected concrete parts. The information can be complemented and adjusted through a suitable combination of microscopic methods. Prepared thin sections are used to determine types of aggregates including the specification of its harmfulness. In combination with concrete fragments taken at least from three height levels of the core (surface-centre-bottom), differences or conformity of concrete porousness, and level and type of mineralization of pores and cracks created by secondary phases, are determined. The identification of created phases and their correlation with applied aggregates can be used for prediction of potential risks. The paper describes additional test methods that can be performed on cores from concrete structures and that are based on macroscopic and microscopic analyses.