STUDY OF MIXED STABILIZATION BY MEANS OF THE IMPEDED SHRINKAGE TEST - FISSURATION TEST

A STUDY IS PRESENTED OF THE TRANSVERSE CRACKING OF PAVEMENTS DUE TO IMPEDED THERMAL SHRINKAGE. AN APPARATUS WAS DEVELOPED TO MEASURE ULTIMATE FLEXURAL STRESS AND TO TEST SOME MIXED STABILIZATION PROCESSES. FLEXURAL STRESS IS MEASURED AS A FUNCTION OF THE TEMPERATURE. IN ORDER TO MAKE A SIGNIFICANT COMPARISON OF DIFFERENT MATERIALS, MEASUREMENTS WERE TAKEN OF THE SLOW TENSILE STRESS, RAPID TENSILE STRESS, COEFFICIENT OF THERMAL EXPANSION, MODULI OF THE MATERIALS STUDIED TOGETHER WITH THE BETA COEFFICIENT (VARIATION IN FLEXURAL STRESS/VARIATION IN TEMPERATURE RATIO). THE MATERIALS STUDIED WERE GRAVEL STABILIZED WITH HYDRAULIC BINDERS TO WHICH A BITUMINOUS EMULSION WAS ADDED. TEST RESULTS SHOW THAT FOR DIFFERENT AGES (60, 180, 360 DAYS FOR GRAVEL-SLAG, 28 AND 96 DAYS FOR GRAVEL-CEMENT) THE MECHANICAL CHARACTERISTICS ARE OF THE ORDER OF 20 TO 30% LOWER. FURTHERMORE THE FLEXURAL STRENGTH IS HARDLY IMPROVED. IT SEEMS THAT MIXED STABILIZATION IS NO SOLUTION TO THE PROBLEM OF CRACKING DUE TO IMPEDED THERMAL SHRINKAGE. ANOTHER APPROACH TO THE PROBLEM IS TO STUDY CHANGES IN THE WIDTH OF CRACKS AND THE PROBLEM OF LOAD TRANSFER ON EXPERIMENTAL SITES.