Different Types of Concrete Remediation

Concrete is an amazing building material but like any other structure it can suffer from a variety of issues. Each situation requires a different approach.

This article will cover a few of the more common situations that require concrete remediation. These include: cracks, popouts, sunken slabs, and corrosion. Each will be addressed with the appropriate repair method.

Cracks

Concrete cracks can be a serious problem for a home or workplace and need to be repaired. They can range from being unsightly to posing a safety risk. In general, they occur as a result of stress on the concrete that is greater than its strength and durability. Identifying the severity and status of a crack is vital before deciding on a repair method. It is also important to determine whether a crack is dormant or active.

Drying shrinkage cracks occur when water molecules from the concrete mix evaporate during curing. This process causes the concrete to expand and contract at different times and causes stresses that lead to cracking.

Wide cracks may be caused by early thermal contraction or by expansion and movement in the concrete. It is essential to repair these types of cracks as they can allow for moisture and dissolved salts to enter the concrete element, creating a corrosive environment for the reinforcing steel.

Popouts

Concrete is a mixture of cement, water and rocks that is used worldwide. It is a strong and durable material, but it does have some flaws that can affect its performance and look. These flaws are called popouts and are caused by aggregate particles that break loose from the surface of the concrete. They are different from cracks because they do not affect the structure or service life of the concrete.

Most popouts are small and resemble cones on the concrete surface. They form when an aggregate particle with a low specific gravity swells due to moisture absorption or freezing in saturated conditions. The resulting expansive pressures cause the offending aggregate to fracture and then rubblize the overlaying surface mortar.

Local aggregates in Central Iowa may contain contaminants that can cause popouts. Although ready mix producers use aggregates that meet Iowa DOT specifications, this does not guarantee the absence of these contaminants. Aggregates with high percentages of clay lumps, friable particles and lignite have a higher likelihood to produce popouts.

Sunken slabs

Sunken concrete slabs not only look unsightly but can be a tripping hazard and may cause injury to family members or visitors to the home. This is a major safety concern and should not be ignored.

When a slab sinks it usually indicates that the soil beneath it was not properly compacted during construction. It can also be caused by water infiltration which causes the soil particles to shift and settle allowing the concrete above to sink.

The best way to repair sunken concrete is by using polyurethane foam injection (polyjacking). This method involves drilling holes in the slab and injecting a two-part structural resin that expands when it comes into contact with air. This process is much less disruptive than traditional methods of raising concrete and is far more cost-effective. It is also much faster and provides a permanent solution to the problem. It also prevents future problems such as erosion and tripping hazards.

Corrosion

Corrosion is an issue that can be found in most concrete structures around the world. It can have serious commercial implications if it’s not addressed quickly. It can degrade the value of a structure and it’s also a safety risk for the building’s occupants.

Corrosion happens when the passive film on the surface of the embedded steel deteriorates due to carbonation and chloride contamination. This allows the corroding steel to attack the concrete in a localised manner and pitting corrosion takes place.

Pitting corrosion is a very aggressive form of corrosion that can result in the structural failure of concrete. This is because the corroding steel expands and puts tensile stresses on the surrounding concrete. The increased volume of the corroding steel also causes the concrete to spall or break apart. This can lead to serious re-occurring maintenance costs for the concrete structure. The only way to get inside the concrete and repair it is through invasive mechanical demolition, which is costly and disruptive to building occupants.

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