TESTING OF THE MEASURING AND STUDY METHODS USED FOR EVALUATING THE WORK OF CONCRETE SPREADERS AND FINISHERS

UERBERPRUEFUNG DER MESS- UND UNTERSUCHUNGSVERFAHREN ZUR BEURTEILUNG DER ARBEIT VON BETONVERTEILERN UND BETONDECKEN FERTIGERN

A SERIES OF TESTS IS TO BE CARRIED OUT ON 10 CONSTRUCTION SITES WHERE CONCRETE SURFACING IS BEING BUILT TO CHECK THE MEASUREMENT AND STUDY METHODS LAID DOWN IN THE OLD QUALITY RECOMMENDATIONS ON MODERN CONCRETE MIXTURES. EACH CONSTRUCTION SITE HAS TO BE TESTED AT LEAST TWICE. THE UNIFORMITY OF THE FILL DENSITY OF THE CONCRETE LAID IS BEING ESTABLISHED AT AT LEAST 12 MEASURING POINTS BY MEANS OF THE COMPACTION MEASURING EQUIPMENT DESCRIBED IN THE OLD "QUALITY RECOMMENDATIONS FOR CONCRETE DISTRIBUTING MACHINES". MOREOVER AT EACH OF THE SAME MEASURING POINTS A CONCRETE SAMPLE IS BEING TAKEN BY MEANS OF A CYLINDER 25 CM IN DIAMETER DRIVEN IN AS FAR AS THE BASE. THE SAMPLE IS BEING DIVIDED INTO TWO PARTS OF EQUAL WEIGHT, ONE PART OF WHICH IS BEING SUBJECTED TO A WEIGHING AND DRYING TEST TO DETERMINE THE MOISTURE CONTENT, WHEREAS THE OTHER PART IS WASHED ON THE 0.25 MM SIEVE AND SIEVED AGAIN AFTER DRYING. AS WELL AS THE PARTICLE DISTRIBUTION OF THE AGGREGATES THE TOTAL MO PARTICLE CONTENT (CEMENT - AGGREGATE UNDER 0.25 MM) IS DETERMINED FROM THE DIFFERENCE IN THE DRY WEIGHTS OF BOTH SAMPLES. IN ORDER TO CHECK COMPACTION, 9 CORES ARE BEING TAKEN FROM AREAS IN WHICH THE CONCRETE COMPOSITION WAS ESTABLISHED DURING MANUFACTURE BY TWO FRESH CONCRETE TESTS. THE BULK DENSITY AND COMPRESSIVE STRENGTH OF EACH CORE IS BEING DETERMINED.