Remedial Technology Pty Ltd has been offering solutions to resolve flooring problems arising out of the use of magnesite as floor covering in Sydney homes in the 1960s and 70s.
Magnesite was commonly used as a floor covering in residential unit development. However, 30 years down the line, following long term exposure to household moisture and water, the magnesite has become the source of chloride ingress into the concrete slab leading to corrosion of the steel reinforcement in the concrete floor. This has resulted in cracking, spalling and lumping of the concrete below the floor covering, with the condition commonly referred to as ‘concrete cancer’.
Remedial Technology’s solution begins with an initial condition assessment, wherein the full extent and severity of the problem is properly identified so that the correct remediation option can be selected. The best approach is to undertake an electrochemical assessment of the concrete slab, which will reveal the level of chloride in the concrete and identify the level of corrosion of the embedded rebars.
Subject to the test results, it is likely that the most straightforward and permanent repair solution can be implemented. This solution involves the removal of the magnesite topping and all chloride affected concrete, cleaning of the rebars, and applying new concrete.
While this method can potentially be a permanent and sound long term solution, a range of alternative remediation options is available including the application of an impressed current cathodic protection system, the application of a chloride extraction system (desalination), the application of sacrificial anode systems around the repair areas and within the good but chloride contaminated concrete areas for corrosion prevention, or the application of sacrificial anodes around the repaired areas combined with the sealing of the remaining area of the floor slab to prevent further ingress of moisture to the embedded steel.
However, these alternatives have their own limitations and can only be implemented subject to certain circumstances including the extent of concrete deterioration, considerations of cost, long term monitoring and maintenance, and various building-specific conditions.
Remedial Technology has been involved in the assessment of various magnesite flooring problems and has delivered suitable and long term solutions in each individual case.