How can you tell if concrete is failing? (2023)

What are the main failures in concrete?

How old is your existing concrete? While concrete is much more resilient than other surfaces, it still has an “expiration” date. If your surface is facing 20-25 years of use, it is probably time to replace the concrete. Exterior concrete faces more elements than interior, so adjust your concrete age accordingly.

For large scale projects like buildings, concrete should last up to 100 years if it's properly cared for. Concrete projects that experience more wear-and-tear like sidewalks and driveways have an expected lifespan of about half that—50 years.

The spalling of concrete, Honeycombing, cracking of the concrete surface, bleeding, crazing, dusting, scaling of the concrete and delamination of concrete are the signs of bad concrete pour.

Compared to other binding materials, the tensile strength of concrete is relatively low. Concrete is less ductile. The weight of concrete is high compared to its strength.

Solution: Keeping air content below 3% can help avoid such concrete failures to a great extent. Care should be taken to ensure the concrete isn't let to finish prematurely. Also, ensure proper conditions during its manufacture to prevent excessive air/water from getting trapped.

Assessing potential exposure before construction or repair can prevent premature deterioration. Specific cement types, water-repellent sealers or chemically-resistant barrier coatings are all common preventative measures to protect concrete against chemical attack.

Deeply spalled concrete can be repaired with a concrete overlay. Think of this as just applying stucco to the concrete. You just mix up some sand, a little hydrated lime and Portland cement and trowel this onto the concrete.

A general rule of thumb is that if a repair requires more than two inches of material then it probably is better to use the replacement method. But being able to repair rather than replace concrete can be a more sustainable route that reduces the carbon footprint.

Does concrete lose its strength over time?

Yes, Cement loses its strength over a period of time.

When it absorbs moisture, it hydrates, and consequently the use of that cement does not contribute to the strength development or it contributes less. Such cement gets hardened and form lumps.

Cracks in concrete are common and they develop when stresses in the concrete exceed its strength. Cracks are often caused by normal shrinkage of the concrete when hardening and drying.

But after freshly mixed concrete has been placed, water in the form of a driving rain can do much more harm than good. Pouring concrete in the rain can compromise its strength, increasing the tendency for dusting and scaling to develop.

Three proven methods of testing fresh concrete at different levels of workability are the slump test, the flow table test, and the Vebe consistometer test. The slump test measures the consistency of freshly mixed concrete of medium consistency and is the most widely used method for assessing its workability.

One of the most repeated problems in concrete is crazing. Crazing occurs when the surface shows several interconnected fine cracks or when the cement paste comes up to the surface and shrinks. Although the concrete strength probably is not affected, cracks will show up when the slab is damp.

Steel Corrosion

Corrosion of embedded steel is the most common cause of concrete problems. As steel corrodes, the corrosion product expands, and this expansion can crack concrete and cause sections to break loose in flakes.

Modern concrete—used in everything from roads to buildings to bridges—can break down in as few as 50 years.

What is the most common symptoms of distress in a concrete structure?

In reality, their life span is more like 50-100 years, and sometimes less. Building codes and policies generally require buildings to survive for several decades, but deterioration can begin in as little as 10 years.

Concrete seems like a stable and permanent material, but it remains porous and will absorb water. When this water trapped inside the concrete freezes, it pushes the cement binder apart. This expansion, and the resulting contraction when the water melts again, causes crumbling.

For worn down concrete, polishing and re-treating with chemical hardeners and sealers is the most common solution for restoring your floor. Aged and damaged concrete that's cracked or pitted with small holes can be repaired with patch material.

Avoid overworking the concrete, especially with vibrating screeds, jitterbugs, or bullfloats. Overworking causes aggregate to settle and bleed water and excess fines to rise.