CALIFORNIA PAVEMENT FAULTING STUDY

DETAILS OF AN INVESTIGATION OF FAULTED CONCRETE PAVEMENTS CONSTRUCTED ON CEMENT TREATED BASES ARE PRESENTED. VARIOUS TESTS AND MEASUREMENTS WERE MADE ON THE PAVEMENTS AND CONSTRUCTION MATERIALS INCLUDING STRAINS, DEFLECTIONS, LOAD TRANSFER EFFECTIVENESS ACROSS THE UNDOWELED JOINTS, JOINT OPENINGS AND MOVEMENTS DUE TO TEMPERATURE CHANGES, SLAB CURL, COMPRESSIVE STRENGTH, AND PETROGRAPHIC AND CHEMICAL TESTS. AT SOME SITES, MOVEMENT OF WATER AT THE SLAB BASE INTERFACE WAS DETERMINED BY THE USE OF COLORED TRACER SANDS PLACED UNDER THE SLABS SEVERAL WEEKS PRIOR TO SLAB REMOVAL OR CORING. PORTIONS OF PAVEMENT SLABS WERE REMOVED AT FOURTEEN SITES IN THREE DIFFERENT GEOGRAPHICAL REGIONS-- VALLEY, COASTAL, AND MOUNTAIN. THE SECTIONS, REMOVED FROM THE OUTER EDGE OF PAVEMENT, WERE THREE FEET WIDE AND EXTENDED APPROXIMATELY THREE FEET ON EITHER SIDE OF THE JOINT. TEN OF THE JOINTS THUS OPENED WERE FAULTED IN AMOUNTS VARYING FROM 0.10-INCH TO 0.30-INCH. AT EACH FAULTED JOINT, A BUILDUP OF GRANULAR MATERIAL WAS FOUND UNDER THE APPROACH SLAB, AND IN SOME INSTANCES, UNDER THE LEAVE SLAB AS WELL. THE BUILDUP DIFFERENTIAL WAS APPROXIMATELY EQUAL TO THE AMOUNT OF FAULTING MEASURED. THERE WAS NO EVIDENT SETTLEMENT OF FAULTING OF THE CEMENT TREATED BASE COURSE. THE MAJOR SOURCE OF THE BUILDUP MATERIAL WAS DEFINITELY IDENTIFIED AS BEING MATERIAL ERODED FROM THE CEMENT TREATED BASE IN ONE INSTANCE, AND THE UNTREATED AGGREGATE BASE FROM THE SHOULDER IN ANOTHER INSTANCE. IT IS CONCLUDED THAT THE FAULTED CONDITION OF THE JOINTS WAS CREATED BY A BUILDUP OF MATERIAL UNDER THE PAVING SLABS AT THE JOINTS. THE BUILDUP WAS CAUSED BY VIOLENT WATER ACTION ON AVAILABLE LOOSE OR ERODABLE MATERIALS WHICH WERE PRESENT BENEATH OR ADJACENT TO THE SLABS. TO PREVENT OR REDUCE FAULTING, MORE EROSION RESISTANT MATERIALS ARE NEEDED AT THE SURFACE OF THE BASE COURSE AND IN THE SHOULDERS. IN ADDITION, CONSIDERATION SHOULD BE GIVEN TO PREVENTING THE INTRUSION OF WATER, OR PROVIDING POSITIVE DRAINAGE. /AUTHOR/