12.2 Common Concrete Defects: Honeycombing, Segregation, Cold Joints & Cracking

12.2 Common Concrete Defects: Honeycombing, Segregation, Cold Joints & Cracking

Visible defects provide evidence about the work and its environment. Start with the location, dimensions, surface condition and placement records. The same visual pattern can have more than one cause. The licensed design professional evaluates structural significance and the appropriate disposition when design review is needed.

1. Compare placement and consolidation observations

Check actual bar spacing using the applicable reinforcement configuration in ACI 318-19 Section 25.2. For parallel nonprestressed bars in a horizontal layer, Section 25.2.1 uses the greatest of the bar diameter, 1 inch, or four-thirds of nominal maximum aggregate size. Congested cages can obstruct concrete and vibrator access even where one local clearance appears adequate. Record measurements and compare them with the detail. Honeycombing at one face can warrant further evaluation to determine its depth and effect on the member.

2. Investigate a placement interruption

A cold joint can form when a delay prevents concrete placements from integrating. A visible layer line can also occur where layers have bonded. Identify the time, location, concrete condition and consolidation at the interface. ACI 301-20 Sections 5.3.2.4(b) and 5.3.2.6 require construction-joint provisions to be met where the next placement would otherwise form a cold joint. Under ACI 318-19 Section 26.5.6.2(a), submit unshown or changed joint locations or details to the licensed design professional for review. Verify the resulting location, steel and specified surface preparation before concealment.

3. Read surface and crack patterns in context

Plastic shrinkage cracks can develop in fresh concrete when surface water evaporates faster than bleeding replaces it. Warm concrete, low humidity and wind can increase evaporation. Compare actual site conditions with the approved protection plan, including any specified evaporation limit. Low-bleeding mixtures can be vulnerable even when the evaporation rate appears moderate.

Crazing is a network of fine cracks at the surface. Dusting is formation of powder on a hardened surface under use. Working bleed water into the surface can weaken the surface layer. Blisters and delamination can develop where a dense surface is sealed before air or bleed water can escape. ACI 301-20 Section 5.3.4.2 addresses the sequencing of unformed surface finishing. Record whether the finish, observed timing and protection match the approved procedure.

Drying shrinkage can crack restrained hardened concrete. Flexural cracks can occur under service loads. An inclined crack near a support can be consistent with shear-related cracking and warrants prompt evaluation in context. For example, if an inclined crack in a beam opens further while construction loads are added, record the change and loading condition and alert the responsible parties promptly. An approximate angle alone cannot establish overstress or the required repair. A crack comparator can document the width at a marked point for comparison at later observations. Use the same location and record any change in the loading or temperature at measurement.

4. Document and track the disposition

1. Locate the condition by member, grid, face and elevation. Record length, orientation and accessible width with the instrument or comparator used. Photograph a scale and wider context. Identify any limits on what could be seen.
2. Record relevant conditions such as fresh-concrete tests, interruptions, curing and loading. Bring the discrepancy to the contractor under model IBC Section 1704.2.4.
3. If the discrepancy remains uncorrected, notify the building official and registered design professional in responsible charge before completion of that phase. Record the accepted evaluation or repair and verify the observed correction. Follow the project’s reporting schedule and emergency procedures for conditions needing urgent attention.