I gave a talk about Efflock to local builders at a Master Builders Association meeting out at Campbelltown last week. An interesting problem was raised, which I have touched on briefly in a previous blog.
A builder at the meeting told me that the soil in the Camden area south west of Sydney is notorious for high salinity. The high salt content presents major problems for standard construction where rising damp can have very damaging effects on brickwork below the DPC or 'Damp Proof Course' level. The DPC is typically located around floor level, meaning that numerous courses of bricks are exposed to rising damp.
In ground with high salinity, rising damp transports ground salts into the brickwork, where moisture evaporates, leaving behind ever increasing salt deposits. Through wetting and drying of normal weather cycles, these salts crystallise to cause fretting or spalling of the brick face. Over a number of years this action can erode the brickwork away completely.
Efflock performs brilliantly to control the transport of salts and water. By including Efflock in the mortar mix of at least the first three courses of brickwork at ground level, rising damp is prevented. Each bed of mortar acts as a DPC to prevent salt attack occuring above ground level where evaporation causes spalling of the brickwork.
The local Camden Council has an excellent document with many photographic examples explaining the problem in detail: http://www.camden.nsw.gov.au/Building_in_a_Saline_Environment.pdf