STUDIES OF THE BEHAVIOUR OF A HEAT-INSULATING COURSE MADE OF POLYSTYRENE FOAM PARTICLE CONCRETE UNDER TRAFFIC LOADING ON A LARGE EXPERIMENTAL SECTION OF THE BERLIN-MUNICH MOTORWAY

UNTERSUCHUNGEN UEBER DAS VERHALTEN EINER WAERMEDAEMMSCHICHT AUS POLYSTRYROLPARTIKELSCHAUM-BETON UNTER VERKEHRS BELASTUNG AUF EINER GROSSVERSUCHSSTRECKE AN DER BAB BERLIN-MUENCHEN

HEAT-INSULATING COURSES IN ROAD CONSTRUCTION HAVE THE TASK OF PREVENTING FROST DAMAGE TO ROADS.THEY SHOULD COMPLETELY OR PARTIALLY REPLACE THE NORMAL GRAVEL FROST BLANKET,AND SHOULD BRING ABOUT ECONOMIC BENEFITS IN AREAS WHERE THE PROCUREMENT OF GRAVEL OR OTHER FROST PROTECTION MATERIALS IS BECOMING TOO EXPENSIVE.EXPERIMENTS WITH THE EXISTING SHORT EXPERIMENTAL SECTIONS OF ROAD WERE FAVOURABLE,AND IN THE REPORT PUBLISHED BY THE FORSCHUNGASGESELLSCHAFT FUER DAS STRASSENWESEN ENTITLED "HEAT-INSULATING LAYERS AS PROTECTION AGAINST FROST" THE FOLLOWING RECOMMENDATIONS WERE MADE: 1 - CHECKING OF THE ECONOMIC EFFECT OF PLACING HEAT- INSULATING COURSES DURING THE WORK OF CONSTRUCTION; 2 - STUDY OF THE BEHAVIOUR OF ROAD PAVEMENTS WITH HEAT- INSULATING COURSES UNDER HEAVY TRAFFIC LOADING; 3 - STUDY OF THE CHANGES WITH TIME OF THE CONDUCTION OF HEAT AS A RESULT OF SOIL MOISTURE; 4 - COMPARATIVE STUDY OF THE ECONOMICS OF METHODS OF CONSTRUCTION WITH AND WITHOUT INSULATING LAYERS; 5 - STUDY OF THE FORMATION OF HOAR FROST WITH CONSTRUCTION METHODS EMPLOYING HEAT-INSULATING COURSES. IT HAS BEEN SHOWN THAT QUESTIONS 1, 2 AND 4 CAN ONLY BE ANSWERED WHEN LONGER EXPERIMENTAL SECTIONS OF ROAD THAN HITHERTO ARE SET UP AND EXPOSED TO HEAVY TRAFFIC LOADING. THE GREATER LENGTH OF THE TEST SITES SHOULD COMPRISE A GREATER NUMBER OF POSSIBLE SUBSOIL CONDITIONS AND HYDROLOGICAL FACTORS.OF THE INSULATING MATERIALS TESTED SO FAR,WHICH CAN SERVE BOTH AS A FROST BLANKET AND AS THE FIRST ROADBASE, "STROPOR CONCRETE" AT THIS STAGE IS PARTICULARLY PROBLEM-FREE TO PLACE AND TO INCLUDE IN CONSTRUCTION OPERATIONS.DURING 1974 A 5 KM LONG CONTRACT SECTION OF THE BERLIN - MUNICH MOTORWAY AT GEFREES IS TO HAVE ITS PAVEMENT RENEWED.HEAT-INSULATING LAYERS ARE TO BE INCORPORATED UNDER THREE DIFFERENT CONDITIONS; BY MEANS OF CONSTRUCTION WITH REMOVAL OF THE EXISTING SUBGRADE,BY CONSTRUCTION WITHOUT REMOVAL OF THE EXISTING SUBGRADE DIRECTLY ONTO THE EXISTING DAMAGED OLD SURFACING,AND CONSTRUCTION WITHOUT REMOVAL OF THE EXISTING SUBGRADE WITH AN INTERIM LAYER OF LOCAL MATERIAL.THE SECTION IS ABOUT 500 M ABOVE SEA-LEVEL.THE SUBSOIL CONSISTS OF WEATHERED AMPHIBOLITE (HORNBLENDE ROCK) AND BANDS OF HORNBLENDE AND GNEISS,AND IS VERY SUSCEPTIBLE TO FROST.TRAFFIC 5OLUME IS CURRENTLY 6680 VEHICLES/24 HRS WITH A 30 PERCENT PROPORTION OF FREIGHT TRANSPORT.