Common Types of Problems in Concrete during Placement!

Common Concrete Pouring Issues

1. AIR LOSS:

During concrete pouring, air loss can cause problems. Several factors lead to this, such as long vertical drops, high initial slump, increase in pressure, or drop in exit. For every 1% decrease in air, strength decreases by 4-5%.

You can fix this problem by adding a gate at the end of the pump line for restriction. It also helps to keep the boom in an upward or horizontal position as much as possible. If this can’t be done you can put multiple 90 degree elbows into the line to slow down concrete, minimizing the straight dropout.

2. BUG HOLES:

Bug holes are evident by a small void on the outside of formed concrete surfaces. These come from poor application of form release agents to form-work or completely forgoing their use entirely. It can also come from stiff or sticky concrete mixtures. This can also be caused by poorly placed internal concrete vibrators.

To solve the problem of bug holes, make sure release agents are applied correctly to form-work. Supervise vibrator placement closely, and check the mixture to make sure its consistency isn’t too stiff. If these fixes don’t work, self-consolidating concrete can also reduce bug holes.

3. HONEY COMBING:
Honeycombing consists of voids left in the concrete is a result of mortar not filling the spaces among coarse aggregate particles. The problems from this can be cosmetic or structural in nature. Honeycombing also happens because of aggregate that is too large or improperly proportioned concrete mix. Limited access for pouring concrete in form-work can also cause problems. Reinforced steel can also block flow.

A viable solution to honeycombing is to minimize steel rebar to reduce flow restrictions. Checking concrete mix proportions and increasing access points for pouring will also help prevent honeycombing. Additionally, you can use self-consolidating concrete, which minimizes the risk of honeycombing.

4. DISCOLORATION:

This problem is related to poor workmanship. You will most probably not have this issue if you’ve hired honest and professional concrete flooring experts
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Discoloration can appear if different cement materials were used, calcium chloride was added to the mix or even if there was too much water on site.

5. SCALING:

Concrete floors might start peeling off if the concrete was not cured properly or the material was of wrong strength to start with.

6. CRAZING:
Concrete floors might start cracking when damp. The causes can be different, including inappropriate finishing and polishing.

7. CRACKING:
If the concrete develops bigger cracks, then yea, you have a cracking issue. This usually happens because of drying shrinkage, thermal contraction, sub-grade settlement, and applied loads.

8. CURLING:
Concrete curling occurs when there is more shrinkage at the bottom once the concrete has hardened. It is primarily due to differences in moisture and or temperature between the top and bottom surfaces.

9. ADDING MORE WATER:

Premature finishing (scrubbing bleed water into the top of a slab thus causing a high w/c ratio, leading to a soft dusty top.

10. INSUFFICIENT CURING:

Concrete should not be allowed to dry before it has reached sufficient strength. The strength you have to pay for Inadequate form-work and Premature stripping.