Influence of Coarse Aggregates on Frost Resistance of concrete from the view point of Scaling Damage

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(1)The freezing and thawing resistance of concrete with very inferior coarse aggregates examined by ASTM C 666 procedure A was not improved solely by the improvement of concrete mixture proportions. However, the scaling resistance examined by ASTM C 672 was greatly improved by the improvement of concrete mixture proportions such as water cement ratio and air content. The difference of these results was guessed possibly due to the different mechanism of freezing and thawing deterioration.(2)The character of pore structures in coarse aggregates had great role to the frost resistance of concrete. In additon, not only pore structures in coarse aggregate, but also its maximum size, were influenced on the scaling resistance of concrete.(3)The maximum size of coarse aggregate also influenced on the scaling resistance.(4)The risks of frost damage and deicer salt scaling damage of concrete could not be estimated solely from density and the water absorption of coarse aggregates. The measures to be specified and the method for estimation of coarse aggregates quality based on mechanism of frost deterioration of concrete must be investigated in detail.(5)Specific testing methods to assess the strength and permeability of concrete were proposed, and their methods were also examined to evaluate the degree and the depth of deterioration caused by frost damage.(6)Measures for the prevention of the frost damage were proposed from the aspect of the design of structure, the mixing of concrete and the execution of work.