Manly National Carpark
Helicrete was chosen as one of the two contractors to carry out the concrete cancer repairs to the multi storey car park floor slabs and columns. There were extensive repairs carried out under the supervision of a remedial structural engineer.
Queenscliff Strata Unit Block
These photos are of several areas of a unit block in Queenscliff which suffered from concrete cancer. The cause was a mixture of reasons, poor steel coverage, the concrete wasn't vibrated during pouring, magnesite topping becoming wet from poor waterproofing of balcony hobs. Helicrete repaired the roof top slab, a concrete beam, concrete column, soffit of a slab, and two floor slabs to lower units under the instruction of a structural engineer and sub contracting to a local builder.
Manly Strata Unit Block
These are images of corroded steel bars within a concrete block balustrade. The blockwork was never filled by the original contractor leaving the voids in the blockwork empty, they should have been filled with concrete. With only render on the top of the wall covering the the steel, they were subject to moisture tracking down the length of steel from the top and as a result the steel corroded causing concrete cancer.
The corroded bars were cut out of the wall and floor slab, replaced with new bars and concreted in place using the same fluid, high strength, low alkali, micro-concrete reinstatement mortar as the above repair.
Again the repairs were overseen by a structural engineer.
The repaired areas were then rendered over ready for painting.
Manly Strata Unit Block
All work was carried out to the overseeing engineer's specifications and took 4 days to complete.
The remedy for this floor was to remove the magnesite topping.
Remove the contaminated concrete around the reinforcing bars.
Clean the bars and apply sacrificial anodes around the perimeter of the repair.
Pouring of new fluid, high strength, low alkali, micro-concrete reinstatement mortar.
Ready for the contractor to come in and tile over the top.
There are many causes of concrete cancer such as lack of coverage around the reinforcing steel. In this instance the kitchen floor had a magnesite topping. Magnesite toppings were previously used largely during the 60's and 70's for levelling of floors and sound deadening, but as the magnesite is exposed to moisture it releases chlorides into the concrete. This in turn attacks the steel reinforcing within the concrete. As the steel corrodes it expands in volume and causes spalling of the surrounding concrete, often referred to as concrete cancer.
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