1975•Unpublished venueRequires access
COMMENTS ON THE WEAR AND ROUGHNESS OF CONCRETE SURFACINGS
J Baron, J L Nissoux, Gilles Bonnet, H Rapin
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Abstract
THE AUTHORS RECALL THAT THE SKIDDING RESISTANCE AND THUS THE SAFETY OF THE ROAD USERS DEPEND ON THE SURFACE CHARACTERISTICS OF THE SURFACING OF A PAVEMENT. THE RESTORATION OF THE SURFACE CHARACTERISTICS THROUGH WEAR IS NOT SUFFCIENT TO ENSURE THE SAFETY OF THE USERS. ONE SOLUTION TO THE PROBLEM IS TO RETAIN THE INITIAL CHARACTERISTICS AS LONG AS POSSIBLE, HENCE THE NECESSITY OF STUDYING THE WEAR OF CONCRETE. OBSERVATIONS AND MEASUREMENTS CARRIED OUT ON SURFACINGS UNDER TRAFFIC SHOW THAT THE AVERAGE YEARLY RATE OF WEAR CAN VARY FROM 0,3 TO 1 MM UNDER AVERAGE MOTORWAY TRAFFIC. THIS VARIATION IS CAUSED BY SUCH FACTORS AS THE CLIMATE OR ASPECTS OF CONCRETE MANUFACTURE. THE INFLUENCE OF THESE FACTORS HIDES THAT OF CONTROLLED PARAMETERS SUCH AS THE HARDNESS OF COARSE AGGREGATES ON THE COMPRESSIVE STRENGTH OF CONCRETE. LABORATORY TESTS SHOW THAT THE RESISTANCE OF CONCRETE TO WEAR BY BALL IMPACT IS RELATED TO ITS MECHANICAL STRENGTH. IT IS KNOWN THAT THE LATTER IS LITTLE AFFECTED BY THE HARDNESS OF COARSE AGGREGATES, AT LEAST FOR COMMONLY USED AGGREGATES, BUT IS MARKEDLY INFLUENCED BY CEMENT PROPORTIONING AND MORTAR POROSITY. THESE FACTS LED THE AUTHORS TO BELIEVE THAT, EVEN IF THE EFFECT OF THE HARDNESS OF COARSE AGGREGATES ON THE WEAR OF CONCRETE COULD BE DETECTED, THIS EFFECT WOULD NOT BE A DECISIVE FACTOR IN THE SELECTION OF AGGREGATES. HOWEVER, IN THE PRESENT STATE OF KNOWLEDGE, IT WOULD BE WRONG TO ASSUME THAT COARSE AGGREGATES OF ANY HARDNESS CAN BE USED. THE TEST RESULTS AND OBSERVATIONS REPORTED IN THIS ARTICLE MUST BE EXAMINED AND ANALYZED IN DEPTH. IN ANY CASE THE HARDNESS OF COARSE AGGREGATES IS LIKELY TO INFLUENCE SEVERAL CHARACTERISTICS OF CONCRETE SURFACINGS AND NOT ONLY THEIR RESISTANCE TO WEAR. GROOVING BY SCRAPING REDUCES THE STATE OF COMPACTION OF THE SURFACE MORTAR AND DECREASES ITS RESISTANCE TO WEAR. IT IS POSSIBLE TO MOULD SUFFICIENTLY DEEP RELIEF IN THE FRESH CONCRETE WITHOUT REDUCING ITS STATE OF COMPACTION SO THAT LONGITUDINAL GROOVING WHICH WOULD ENSURE A DURABLE IMPROVED SAFETY FOR THE ROAD USERS.