1. Home
  2. TRID
  3. View Record
https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

BONDED CONCRETE CURES AILING BRIDGE DECKS

A SERIOUS ATTACK ON THE DECK DETERIORATION PROBLEM IN IOWA BEGAN IN 1963 WHEN A RESEARCH PROJECT WAS LAUNCHED TO INVESTIGATE REPAIR METHODS AND MATERIALS. THE FIRST EFFORT WAS TO DEVELOP A METHOD OF PARTIAL DEPTH PATCHING OF SPALLED AREAS HAVING GOOD BOND, LITTLE OR NO SHRINKAGE DURING AND AFTER CURING, AND RAPID READINESS FOR TRAFFIC. THE BEST RESULTS WERE OBTAINED FROM LOW SLUMP AIR-ENTRAINED CONCRETE USING SAND-CEMENT GROUT AS THE BONDING AGENT OVER A CAREFULLY PREPARED SURFACE. IN THE 1964 SPRING, STATE MAINTENANCE PERSONNEL BEGAN PLACING PARTIAL DEPTH PATCHES WITH THIS MATERIAL. ALSO, 1964 MARKED THE START OF A PARALLEL RESEARCH PROJECT TO DETERMINE HOW BEST TO RESURFACE COMPLETE DECKS WITH A THIN LAYER OF PORTLAND CEMENT CONCRETE. THE ENGINEERS SELECTED A 240-FT TWO-LANE BRIDGE THAT HAD NUMEROUS SURFACE SPALLS IN THE DECK. SOME OF THE TOP REINFORCING HAD RECEIVED ONLY 1/2 IN. OF CONCRETE COVERING. THE SAME PRINCIPLES AND BASIC PROCEDURES AS USED IN SMALL-AREA PATCHES WERE FOLLOWED FOR THIS INITIAL 1 1/2- IN. DEPTH RESURFACING PROJECT. THE METHOD USED FOR THIS 240 FT. BRIDGE STILL PREVAILS IN IOWA'S CONTRACT RESURFACING PROGRAM FOR ARTERIAL AND FREEWAY BRIDGE DECKS. OVER 100 BRIDGES HAVE BEEN RESURFACED IN THIS MANNER, WHILE THE ENGINEERS CONTINUE TO OBSERVE THE PERFORMANCE OF DECK RENOVATION BY OTHER MEANS. SOME MINOR LOCALIZED FAILURES HAVE OCCURRED. SOMETIMES BOND IS LOST AT SPOTS WHERE AN AIR COMPRESSOR MAY HAVE LEAKED OIL AND THE IMPREGNATED AREA OF OLD CONCRETE WAS NOT FULLY CHIPPED OUT. MOST OVERLAY AREAS WITH CONCRETE HAVE SHOWN NO DETERIORATION TO DATE, DESPITE OFTEN HEAVY TRAFFIC AND IOWA'S SEVERE CLIMATIC RANGE. IN STUDYING CORES TAKEN FROM REPAIRED DECK AREAS, STRENGTH IS NOT THE CHIEF CONCERN BUT RATHER THE AMOUNT AND DEPTH OF CHLORIDE INFILTRATION THAT MIGHT REACH THE REINFORCING STEEL. CORES TAKEN IN ORIGINAL DECK CONSTRUCTION IN 1972 AND 1973 BY THE FEDERAL HIGHWAY ADMINISTRATION HAVE BEEN COMPARED WITH MORE RECENT CORES FROM RESURFACED AREAS. THESE CORES SHOW VARYING AMOUNTS OF CHLORIDE INFILTRATION, AND ARE STILL BEING STUDIED WITH NO CONCLUSIONS FORMALLY DRAWN TO DATE. THE CORES SHOW THAT SOME RESURFACES HAVE NOT BEEN AS SUCCESSFUL AS OTHERS IN PREVENTING SALT FROM GETTING DOWN INTO THE CONCRETE. THIS IS BELIEVED TO POINT UP THE IMPORTANCE OF OBTAINING GOOD COMPACTION OR CONSOLIDATION OF CONCRETE ON BRIDGES WHERE DEICING MATERIAL IS HEAVILY APPLIED. THE COST OF THIS METHOD OF DECK RENOVATION IS HIGH-FROM $23 TO AS HIGH AS $54 PER SQ YD FOR VARIOUS CONTRACTS IN DIFFERENT YEARS. BUT THE COST IS CONSIDERED LOW ON A PER YEAR SERVICE BASIS, COMPARED WITH OVERLAY BY OTHER METHODS. ALSO THERE IS THE BONUS OF INCURRING LESS FREQUENT TRAFFIC INTERRUPTIONS FOR REPAIRS.

  • Publication Date: 1974-5

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00219197
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 31 1974 12:00AM