PCR Prostar Concrete Restorations

It is estimated there is almost 1 billion cu. yds. of "in-place" concrete in Canada, most of which is more than 20 years old. The use of concrete in construction has continued to grow rapidly, from approximately 22 million cu. yds. in 1990 to 40 million cu. yds. in 2004. This significant quantity of concrete and strong growth rate of concrete use in construction translates into a Canadian repair market of more than $1.8 billion per year.

These statistics indicate that the typical repair involving deteriorated concrete and corrosion of reinforcing rebar will become more frequent. Before defining a specific repair method, we will consult an engineer with the appropriate expertise for an assessment of the key dynamics behind the deteriorating concrete. The engineer examines the extent of structural damage, along with a determination of the cause, in order to design a material repair system that will ensure integrity and durability of the structure.

Incomplete concrete repairs and insufficient corrosion protection cost building owners considerable time and money. Prostar suggests a simple, yet often overlooked, step of concrete repair that has proven successful worldwide in ensuring the integrity and durability of concrete repairs while significantly lowering overall lifecycle costs.

Concrete Deterioration

Virtually all concrete has at least small micro-cracks. These minute cracks, combined with the natural porosity of concrete, open an avenue for chloride (carried by moisture) to penetrate into the concrete, eventually reaching the rebar. As the rebar corrodes, it expands, "blowing" off the cover of concrete, and accelerating the cycle of deterioration.

When concrete is first poured, its high alkalinity serves as a passivating barrier, protecting the rebar from corrosion. However, as time goes on and the concrete is exposed to the environment, carbonation takes place, reducing the alkalinity and breaking down the passivating barrier. In time, carbonation will reach the depth of the rebar and corrosion cells will develop.

While chloride penetration and carbonation work closely together to deteriorate concrete, other aspects -such as the quality of the concrete and design of the structure- play a pivotal role. The bottom line: Even if the best available concrete repair mortar is used (i.e., high-density and dimensionally stable), carbonation and chloride penetration are working virtually 24/7 to undermine any repair effort.

Prostar's Process to repair and prevent future corrosion

1.Remove deteriorated concrete and profile the surface according to specifications of the repair material's manufacturer. This includes the removal of any carbonated or chloride-impregnated concrete.

2.
Most of patch repair on flat surfaces (concrete spalling) will require saw cut to create a good bonding edge to prevent future water ingress and chipping.

3.
Clean rebar with an appropriate method to remove all corrosion, and repair appropriately to ensure the integrity of the completed repair.

4.
Coat the exposed rebar with a high-performance anti-corrosion and bonding agent. To improve bonding of the repair mortar to existing concrete, coat all areas of the repair with the same bonding agent.

5.
Select an appropriate repair mortar with the required performance and application characteristics.

6.
To further solidify the repair's longevity by an exponential factor, thus decreasing lifecycle costs to the owner,Prostar suggests coating the entire structure -both the original concrete as well as the repaired area- with a cementitious, flexible waterproofing and protective coating.

Please go to the file download link on the right pane for glossary of terms.

VISIT PROSTAR CONCRETE RESTORATIONS GALLERY

It is estimated there is almost 1 billion cu. yds. of "in-place" concrete in Canada, most of which is more than 20 years old.