CONCRETE PROBE-STRENGTH STUDY

THE WINDSOR PROBE - TEST SYSTEM WAS EVALUATED FOR DETERMINING COMPRESSIVE STRENGTH OF CONCRETE BY COMPARING PROBE STRENGTHS AGAINST CYLINDER AND CORE STRENGTHS FROM BOTH LABORATORY AND FIELD-POURED CONCRETE. ADVANTAGES AND DISADVANTAGES OF THIS SYSTEM WERE OF PRIME CONSIDERATION WHILE COST AND EFFICIENCY WERE ALSO TAKEN INTO ACCOUNT. THE PROBE TEST COMPRESSES A SECTION OF THE CONCRETE BY FORCED ENTRY OF A HARDENED ALLOY PROBE DRIVEN INTO THE CONCRETE BY A SPECIAL GUN. LABORATORY PREPARED TEST SLABS WERE POURED ALONG WITH STANDARD CONCRETE CYLINDERS AND BEAMS. AT VARIOUS AGES, SLABS WERE TESTED USING THE PROBE AND CYLINDERS WERE TESTED FOR COMPRESSIVE STRENGTHS. CORES OF THE SLABS WERE TAKEN FOR STRENGTH COMPARISONS. FROM THIS DATA TWO STRENGTH CURVES WERE DERIVED. THESE SAME PROCEDURES WERE USED FOR THE FIELD PROJECTS USING THE SAME TYPE OF AGGREGATE (CHERT) BUT FROM DIFFERENT SOURCES. THESE RESULTS WERE COMPARED TO LABORATORY CURVES AND SHOW FIELD STRENGTHS FOR CYLINDERS AND CORES TO VARY CONSIDERABLY FROM THE LABORATORY CURVES. THE WINDSOR PROBE - TEST SYSTEM IS FAST, EASY TO USE AND LESS EXPENSIVE THAN CORING. IT GIVES GOOD RESULTS WHEN USING SAME MATERIAL, AGGREGATE SOURCE AND MIX DESIGN. PROBLEMS EXIST WITH USE OF PROBE IN HARD AGGREGATE SUCH AS PROBES BREAKING, ENTERING CONCRETE CROOKED, AND BEING LOOSE AND CAUSING SPALLING. OPERATOR TECHNIQUE DOES PLAY A PART IN OBTAINING GOOD RESULTS. FURTHER STUDY USING THIS SYSTEM SHOULD BE MADE UNDER VARYING CONDITIONS BEFORE IT IS ACCEPTED AS A DEVICE TO REPLACE CYLINDERS AND CORES FOR DETERMINING COMPRESSIVE STRENGTH OF CONCRETE. /AUTHOR/