Key Causes of Concrete Degradation

If your concrete patio or exposed aggregate driveway is looking a bit worse for wear, obviously you’ll want to find out why. There are multiple reasons for concrete degradation, so having a basic knowledge of these is the best way to prevent your concrete from getting damaged. Read on to learn some of the most common causes of concrete deterioration.

Corrosion of reinforcing steel

Steel is often used in concrete slabs as a reinforcement, and the naturally alkaline nature of concrete helps prevent this steel from rust. However, if chloride ions somehow become present in the concrete (in Melbourne the most likely causes are chloride from seawater, and, less common, groundwater and soil) they can destroy the “passivating layer” in the concrete, leading to higher risk of corrosion, which will damage the overall structure. The best way to prevent against this is by limiting the porosity of concrete, in terms of pore distribution and pore system interconnectivity. This is determined by the type of cement and mix proportions used, compaction and curing, which it’s why it’s so important to have a professional concrete contractor in Melbourne install your concrete slabs for you.

Alkali-aggregate reaction

Alkali aggregate reaction is another concrete issue that can destroy concrete from the inside. The most common form is alkali-silica reaction, where reactive silica containing aggregate in the concrete forms a gel, which swells as it absorbs water. The expansive pressure from this gel can be enough to permanently damage the concrete.

Plastic shrinkage cracks or crazing

Crazing (otherwise known as plastic shrinkage) occurs not long after placement, and although it doesn’t pose much of a threat to the structural integrity of the concrete, it can look quite ugly. Crazing occurs when the surface evaporation rate is faster than the moisture gain from curing. This can be a result of exposure to direct sunlight, low humidity or drying winds, which is why a professional concrete contractor will only take on jobs in appropriate weather conditions.


If the surface of your concrete driveway looks bubbled or blistered, it may be that the concrete was prematurely finished and sealed. If concrete is sealed too early, air bubbles and bleed water can be sealed in, giving it an uneven appearance.

If your concrete exhibits any of the signs of the above issues, it may be time to get it replaced. Alternatively, if you’re considering laying a new concrete driveway or patio, make sure you enlist the services of a reputable concrete contractor in Melbourne like Prestige Concrete. We offer a range of services, from coloured concrete to exposed aggregate, so call us today on 0411 440 157.