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Abstract

The objective of the presented paper is to investigate the performance of concrete containing volcanic scoria as cement replacement after 7, 28, 90, and 180 days curing. Five performance indicators have been studied. Compressive strength, water permeability, porosity, chloride penetrability, and reinforcement corrosion resistance have all been evaluated. Concrete specimens were produced with replacement levels ranging from 10 to 35%. Test results revealed that curing time had a large influence on all the examined performance indicators of scoria-based concrete. Water permeability, porosity, and chloride penetrability of scoria-based concrete mixes were much lower than that of plain concrete. Concretes produced with scoria-based binders also decelerated rebar corrosion, particularly after longer curing times. Furthermore, an estimation equation has been developed by the authors to predict the studied performance indicators, focusing on the curing time and the replacement level of volcanic scoria. SEM/EDX analysis has been reported as well.
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Abstract

The objective of this investigation was comparing the penetration of chloride ions in ordinary and air-entrained concretes containing a waste material Fluidized Bed Combustion Fly Ash (FBCFA). All concretes were tested with 15% and 30% cement replacement by FBCFA, with the same water-binder ratio of 0.45. Two kinds of fly ash coming from fluid bed combustion in two power plants in Poland have been used. In this study the rapid chloride permeability test – Nordtest Method BUILD 492 method – was used. The microstructure of the concrete was analyzed on thin polished sections and the measurement of air voids sizes and their distribution, using digital image analysis, was carried on according to PN-EN 480-11:2008. Obtained results have shown a significant influence of partial cement replacement by FBCFA on the chloride ions movements in concrete. It has been found that this kind of addition reduced considerably the chloride ion penetration. The influence of air entrainment on the chloride diffusion coefficients was also measured and it was shown that application of air-entraining admixture for concretes with FBCFA reduce the chloride diffusion coefficient but it should be used with caution.
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