MEASUREMENTS ON CONCRETE PAVEMENTS HAVING HEAT-INSULATING AND STABILISED HYDRAULICALLY BOUND BASES

MESSUNGEN AN BETONDECKEN MIT WAERMEDAEMMENDEN UND VERSTAERKTEN HYDRAULISCH GEBUNDENEN TRAGSCHICHTEN

PART OF THE RECONSTRUCTION OF THE A81 MOTORWAY BETWEEN WEINSBERG AND WUERSBURG INCLUDED THE INCORPORATION OF TWO EXPERIMENTAL SECTIONS, EACH 1.5 KM LONG, HAVING HEAT-INSULATING COURSES AND/OR STRENGTHENED HYDRAULICALLY BOUND GRAVEL ROADBASES UNDER CONCRETE SURFACINGS. IN A PREVIOUS PROJECT MEASUREMENTS OF TEMPERATURE, JOINTS AND SETTLEMENTS WERE MADE ON THIS SUPPORTING SYSTEM AND ALSO ON ANOTHER SECTION HAVING A CONVENTIONAL FROST BLANKET. A COMPARISON OF THE DEFLECTION LINES OF THE CONCRETE SURFACING IN THE MIDDLE OF THE SLAB SHOWS THAT SETTLEMENT UNDER THE REAR AXLE OF A HEAVY VEHICLE BEFORE THE ROAD WAS OPENED TO TRAFFIC AND ONE YEAR AFTERWARDS HAD NOT CHANGED. AS THE BONDING ACTION BETWEEN THE CONCRETE SURFACING AND THE ROADBASE LEADS TO A NOTABLE DECREASE IN THE STRESS AND THUS TO AN INCREASE IN THE LIFE OF THE SUPPORTING SYSTEM, TESTS ARE TO BE CARRIED OUT AFTER A PERIOD OF SEVERAL YEARS, IN WHICH THERE HAVE BEEN MANY TEMPERATURE AND TRAFFIC LOADING EFFECTS, TO SEE WHETHER A CHANGE IN THE BONDING ACTION HAS OCCURRED. THE TESTS WILL INCLUDE A REPETITION OF THE SETTLEMENT MEASUREMENTS IN THE CENTRE OF THE SLAB AND AT THE EDGE OF THE JOINTS, AND A CONTINUATION OF THE JOINT AND TEMPERATURE MEASUREMENTS AS THE WINTERS OF 1974/5 AND 1975/6 WERE VERY MILD AND FROST ACTION WAS RELATIVELY SLIGHT.