GGBS Reducing Concrete Erosion across Australia
The issue of concrete cancer and erosion has become increasingly common across Australia from the 1960’s. Since then the problem has only escalated and is now a widespread problem on Queensland’s east coast. This is because this area is prone to the three (3) major causes of Alkali-Silica Reaction (ASR) or concrete cancer. These include:
1. A high moisture level within the concrete.
2. The use of concrete that has a high reactive alkali content, or there is another source of reactive alkali.
3. The aggregate contains an alkali reactive constituent.
ASR’s are evident in numerous steel-reinforced 1970’s-1980’s apartment towers and complexes. Laws are now under review, which prevent the timely repair of concrete cancer in older high-rise buildings. The property council of Australia’s senior property body is calling for changes to this legislation. Strata Community Australia’s President James Freestun believes that concrete cancer checks need to be conducted every 2-3 years.
The result of untreated concrete cancer can include costly repairs and buildings that have irreparable damage. This presents problems not only for the investors or tenants, but also for the community in general.
Not all hope is lost however. The graph attached (right) highlights the role that Ground Granulated Blast-Furnace Slag (GGBFS) plays in reducing ASR (Civil & Marine Fact Sheet, 2001). It is believed that the alkalis present in GGBFS are combined in the glassy structure so that these alkalis are not able to promote the ASR in the same manner as the alkalis derived from Portland cement. Also, the incorporation of GGBFS reduces the permeability of the hardened concrete and thereby limits the ability of the alkalis to move through the concrete to reactive sites. (Civil & Marine Fact Sheet, 2001)
GGBFS is commonly found in low carbon cements and concretes, which is now commonly used across Australia but also the world. To read more about the benefits and applications of GGBFS, click here. or visit our library of technical documents.