LATEX-MODIFIED MORTAR IN THE RESTORATION OF BRIDGE STRUCTURES

A SYNTHETIC LATEX EMULSION ADMIXTURE WAS USED WITH PORTLAND CEMENT MORTAR IN THIN PATCHING MIXTURES. LABORATORY STUDY SHOWED IMPROVEMENT IN SHEAR BOND STRENGTH, COMPRESSIVE STRENGTH, TENSILE STRENGTH, AND A REDUCTION OF WATER-CEMENT RATIO AS COMPARED TO REGULAR MORTAR. THE LATEX EMULSION WAS ADDED IN AMOUNTS OF 10 TO 20 PERCENT BASED ON LATEX SOLIDS TO CEMENT WEIGHT. IT WAS USED IN MORTARS HAVING SAND-CEMENT RATIOS OF 3:1 AND 2:1 BY WEIGHT. THIN PATCHING WAS APPLIED TO A BASCULE BRIDGE DECK IN CHEBOYGAN, MICH., DURING THE FALL OF 1957. EVALUATIONS OF THE THIN PATCHED DECK SHOW THAT AREAS WHERE THE LATEX MORTAR WAS APPLIED OVER A SOUND, WET SUBSTRATE HELD UP WELL THROUGH TWO WINTERS. BOND FAILED DURING THE FIRST YEAR IN VARYING DEGREES IN AREAS COVERED DRY, WITH LATEX-CEMENT SLURRY, OR WITH A BRUSH COAT OF THE LATEX EMULSION ONLY. THE 1957 AREAS WHERE BOND FAILED WERE REPAIRED IN LATE 1958 BY APPLYING A DIFFERENT LATEX MORTAR OVER A CLEANED SUBSTRATE SOAKED WITH WATER PRIOR TO THE PATCHING APPLICATION. AFTER ONE WINTER THESE AREAS APPEAR TO BE WELL BONDED TO THE OLD SURFACE. A FEW AREAS CONTAIN SOME FINE SHRINKAGE CRACKS BUT DO NOT APPEAR TO BE LOOSENING. THE MORTAR MIXES OF 1957 CONTAINED A WATER-DISPERSED RESIN OF A STYRENE-BUTADIENE COPOLYMER. A NEW LATEX EMULSION OF A SARAN TYPE WAS USED IN THE 1958 PATCHING MORTARS.

Media Info

  • Monograph Title: Repair of structures and pavement by thin concrete patching
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00218387
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Sep 16 1994 12:00AM