COMPOSITION AND PROPERTIES OF CONCRETE AGGREGATE

ZUSAMMENSETZUNG UND EIGENSCHAFTEN VON BETONZUSCHLAG

TESTS ON BUILDING SITES IN SOME PARTS OF NORTHERN GERMANY SHOWED THAT A REACTION TAKES PLACE BETWEEN ALKALI-SENSITIVE COMPONENTS OF THE CONCRETE AGGREGATE OBTAINED AND THE ALKALIS CONTAINED IN THE PORE SOLUTION OF THE CONCRETE, WHICH, COINCIDING WITH UNFAVOURABLE CONDITIONS MAY LEAD TO DAMAGE IN THE CONCRETE. ON ACCOUNT OF THE PARTICULAR CONDITIONS IN NORTH GERMANY THIS MIGHT NOT BE DIRECTLY RELATED TO THE EXPERIENCE OF OTHER COUNTRIES. IT WAS THEREFORE NECESSARY, IN AN EXTENSIVE TEST PROGRAMME TO EXAMINE MORE CLOSELY THE COMPOSITION OF THE AGGREGATE AND ITS REACTIONS IN THE CONCRETE IN ORDER TO DISCOVER MEASURES TO PREVENT DAMAGE TO THE CONCRETE. IN THIS PROGRAMME, AMONG OTHER THINGS, THE PROPERTIES OF NORTH GERMAN CONCRETE AGGREGATES ARE TESTED USING PETROGRAPHIC, CHEMICAL AND PHYSICAL TESTS. THE EFFECT OF, FOR EXAMPLE, THE TYPE, AMOUNT, AND PARTICLE DISTRIBUTION OF THE SENSITIVE AGGREGATE, THE DIFFERENT PROPERTIES OF THE CEMENT AND THE ENVIRONMENTAL CONDITIONS ON THE REACTION TAKING PLACE BETWEEN ALKALI AND AGGREGATE HAS ALREADY BEEN TESTED FOR A LONG TIME USING CONCRETE TEST SPECIMENS OF DIFFERENT DIMENSIONS.