COMPARATIVE STUDIES TO ESTABLISH THE SUITABILITY OF METHODS OF EVALUATING THE QUALITY OF SAND (GROUP ANALYSIS)

VERGLEICHSUNTERSUCHUNGEN ZUR FESTSTELLUNG DER EIGNUNG VON PRUEFVERFAHREN ZUR BEURTEILUNG DER SANDQUALITAET (RINGANALYSE)

THE COMPARATIVE STUDIES SHOULD ENABLE A SELECTION TO BE MADE OF THOSE TEST PROCEDURES IN A SERIES WHICH ARE MOST SUITABLE FOR CHARACTERISING THE STRENGTH PROPERTIES OF SANDS. THE MOST IMPORTANT CRITERIA FOR SELECTION ARE THE RELEVANCE OF THE TEST RESULTS TO THE ACTUAL BEHAVIOUR OF THE SANDS IN PRACTICE, AND GOOD REPEATABILITY AND COMPARABILITY. IN THE SAND TESTING PROCEDURES A DISTINCTION IS MADE BETWEEN THOSE IN WHICH SAND IS EXAMINED FOR ITS OWN SAKE (COMPRESSION TEST AND IMPACT TEST ACCORDING TO DIN 52109) AND THOSE IN WHICH THE SAND IS TESTED IN ITS COMPACTED STATE AFTER BEING COATED WITH BITUMEN (IMPACT AND VIBRATION ABRASION TESTING). WHEREAS THE TEST PROCEDURES IN THE FIRST GROUP SHOULD INDICATE THE PRIMARY FEATURES OF THE SANDS, IF THE TEST PROCEDURES IN THE SECOND GROUP ARE MODIFIED THEY WILL ALSO PROVIDE DATA ON THE PROBABLE WEATHER RESISTANCE OF THE SANDS. AS WELL AS THE ABOVE FEATURES, PARTICLE SIZE DISTRIBUTION IS ALSO TO BE DETERMINED BY AIR JET SIEVING. AIR JET SIEVING IS AN OBJECTIVE METHOD OF ANALYSING PARTICLE SIZE, AND IN CONTRAST TO THE DIN 1996 SHEET 14 METHOD IS NOT AFFECTED BY THE LABORATORY TECHNICIAN.