Concrete Repair Specialists
Concrete repairs, especially those at height, must be made to last. Therefore it is essential to ensure that the correct concrete repair method is used in the first place.
As a specialist concrete repair company, we’ve carried out a wide range of concrete repairs in difficult access locations such as office blocks, apartment buildings, silos or even lighthouses!
We recommend complete testing prior to starting the concrete repair work.
Call us today on 0800 1588 318
Lasting Concrete Repairs require the appropriate repair for the job!
A few insights into Concrete…
What is Concrete and when did it first appear ?
Concrete is the most widely used construction material in the world, and its rise to this position has played a major part in the shaping of civilisation from as long ago as 7000 BC. It is the second most-used substance by man, after water!
It was known to the Romans, the Egyptians and to even earlier Neolithic civilisations. The foundations of the Colosseum in Rome were made of dense concrete (in 82AD), while lightweight concrete was used in some of the arches and vaults.
After the collapse of the Roman Empire its secrets were almost lost, only to be rediscovered in more recent times. Indeed its modern development spans no more than 175 years; 1824 is the date on the patent for the manufacture of the first Portland cement, one of the most important milestones in concrete’s history.
Concrete is a building material composed of cement, crushed rock or gravel, sand and water, often with chemical admixtures and other materials; this mixture eventually hardens into a stone-like material.
How does concrete fail and what causes it?
Anyone involved in the maintenance of reinforced concrete structures cannot be unaware of the substantial increase in the amount of repair work now being carried out.
This may merely reflect the fact that a large number of reinforced concrete structures are now coming-of-age although certain changes in materials have been identified over the past twenty years or so which might be partially responsible in some cases.
From our experience it is true to say that 90% of the problems that will be experienced in concrete repair will involve steel reinforcement corrosion as a primary problem. For the most part this will have been caused entirely by simple carbonation/low cover and/or the presence of chloride salts either from calcium chloride used as an accelerator, or even from de-icing salt.
However, in some cases, some other more subtle defect may be present, such as a shrinkable aggregate, alkali silica reaction, frost attack, sulfate attack, structural cracks or a whole variety of other possibilities.
It must be borne in mind that many of these phenomena may reveal themselves first of all in areas of low cover and carbonated concrete, perhaps because microcracking from one or other of these causes has permitted carbonation to advance more rapidly than might otherwise have been the case.
In such cases, it is all too easy to look at the effects of the problem, and not the cause; steel corrosion is the SYMPTOM, not the CAUSE. Attempting to repair concrete by simply addressing the symptom may simply mean that the problem recurs in a relatively short space of time.
How to recognise concrete damage
Actual structural failure, or even structural cracking is only rarely encountered but it is important to differentiate between cracking from structural and other causes. Such an assessment should only be carried out by a structural engineer, but an initial inspection by a concrete repair contractor and further testing may highlight other (much more likely) causes of cracking.
A concrete repair specialist will know when the advice of a structural engineer is required.
Did You Know ?
Cement and water are the two ingredients that do all the chemical reacting. The gravel and sand give strength.
- If you mix gravel, sand and water together, nothing will happen
- If you mix cement, dry gravel and dry sand together, nothing will happen
- It is only when the cement is mixed with the water that something happens!
Steel corrosion damage in concrete
There are two main causes of corrosion of steel in concrete; chloride attack and Carbonation.
These mechanisms of these factors are unusual in that they do not attack the integrity of the concrete. Instead, aggressive chemical species pass through the pores in the concrete and attack the steel. This is unlike a ‘normal’ deterioration process due to chemical attack on concrete. Other acids and aggressive ions such as sulphate destroy the integrity of the concrete before the steel is affected.
Most forms of chemical attack are therefore concrete problems before they are corrosion problems. Carbon dioxide and the chloride ion are very unusual in penetrating the concrete without significantly damaging it.
Accounts of acid rain causing corrosion of steel embedded in concrete are unsubstantiated – only carbon dioxide and the chloride ion have been shown to attack the steel and not the concrete.