Anyone who has ever worked with concrete will tell you that placing and finishing in hot, dry conditions can be a major challenge. The combination of high temperatures, winds, and low humidity can increase the rate of evaporation of moisture from the fresh concrete, accelerating the rate of cement hydration. This, in turn, can lead to several significant problems with concrete placement and finishing, including plastic shrinkage cracking, increased permeability, a reduction in final strength, and a sub-standard slab.
Even though the Australian Standard AS1379: Specification and Supply of Concrete stipulates a 35°C maximum concrete temperature at the time of delivery, the general rule of thumb is that additional measures need to be taken to control the cement hydration process when the ambient temperature reaches 30°C.
Interestingly, while a common traditional solution is to ‘wet cure’ the concrete – either by spraying the freshly finished concrete with water, covering it with wet canvas or other material, or ‘ponding’ water over the surface – these methods not only tend to be labour-intensive but can also result in an inordinate amount of water being wasted.
MasterKure Range of Curing Agents and Evaporation Retardants
To overcome these challenges, Master Builders Solutions developed the MasterKure range of curing agents and evaporation retardants.
With products to suit a wide range of applications and mix types, MasterKure helps to control the curing process in elevated temperature conditions, slowing cement hydration and protecting the freshly poured concrete.
One product in the Master Builders Solutions range that is especially effective in combating drying shrinkage cracking in hot weather concrete is MasterKure 111.
MasterKure 111: This is not a curing agent; rather, it is an evaporation retardant and finishing aid that has been specifically developed to assist in producing high-quality concrete flatwork in rapid-drying conditions such as high temperatures, low humidity, and high winds. It retards water evaporation during trowelling and regulates the surface condition of the slab during finishing. MasterKure 111 can be used with all types of concrete slabs, toppings, and finishing operations including concrete containing water-reducing, retarding, or accelerating admixtures, and air-entrained concrete. It can be used with tilt-up, lift slab, precast, or prestressed concrete, either with or without membrane-type curing compounds.