Methods of Preparing Horizontal Construction Joints in Mass Concrete

This report presents the results of a research program examining the effects of different methods of preparing horizontal construction joints in mass concrete construction. The purpose of the research program was to confirm existing guidance or, if necessary, update it. The joint cleaning procedures...

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Bibliographic Details
Main Authors: Neeley, Billy D, Poole, Toy S
Format: Report
Language:English
Subjects:
AGGREGATES(MATERIALS)
BONDED JOINTS
CLEANING
COHESION
COMPRESSIVE STRENGTH
CONCRETE
Construction Equipment, Materials & Supplies
CONSTRUCTION MATERIALS
Couplers, Fasteners, and Joints
CUTTING
EMPLACEMENT
FAILURE(MECHANICS)
FLY ASH
GRADATION
GRAIN SIZE
HORIZONTAL ORIENTATION
MOISTURE CONTENT
PERMEABILITY
PORTLAND CEMENT
SAND
SHEAR STRENGTH
SIEVE ANALYSIS
STRENGTH(MECHANICS)
SURFACE ANALYSIS
TENSILE STRENGTH
WATERTIGHTNESS
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Summary:This report presents the results of a research program examining the effects of different methods of preparing horizontal construction joints in mass concrete construction. The purpose of the research program was to confirm existing guidance or, if necessary, update it. The joint cleaning procedures employed were (a) none, (b) high-pressure water cutting, (c) air-water cutting, and (d) air-water cutting to greater depth. The joint moisture conditions at the time of concrete placement were (a) continuously moist, (b) dry, and (c) dry and then remoistened. Jointed specimens were tested for direct tensil strength, shear strength, and permeability. The results indicated that good bond strengths are realized when horizontal construction joints are cleaned by high-pressure water cutting or by air-water cutting, and that undercutting coarse aggregate particles does not improve the strength of the joint. The results also indicated that better bond strengths are realized when the joint surface is allowed to dry approximately 24 hr immediately prior to placement of the next lift of concrete. Recommendations are made to consider revising current guidance to permit placement of concrete on a dry surface. No revisions to current guidance are recommended concerning joint cleaning procedures.