Discovering your rendered wall is dry, powdery and soft during the cooler months? It might not be getting sufficient water to cure correctly.
To form concrete, 3 components are needed:
Cement + Sand + Water = Concrete
It is a typical misconception that water is used just to mix the concrete and when it dries, the concrete should be hard. Water is actually required in addition to the cement and sand for the concrete to fully cure. Throughout the mixing process, the addition of water causes a chemical response to occur. This is described as ‘hydration’. The remainder of the water is then lost to the air through drying. This takes place rapidly in dry (low humidity) temperature levels and if the water evaporates prior to the cement has actually totally hydrated, it can cause dry, soft and grainy render.
The formation of concrete requires time, with a period of around 28 days for concrete to completely solidify. Presuming it has suitable wetness, concrete takes about 7 days to reach 80% of strength at 25 ° C. At low temperatures the preliminary setting of concrete is considerably slower: at 5 ° C it takes 5 days to accomplish the very same strength as 1 day at 40 ° C.
So exactly what occurs in dry weather?
Walls draw wetness from the render more rapidly.
The air will dry the render quickly, especially when integrated with windy conditions (a heavy dew overnight will help in hydration, however in dry and windy conditions this does not take place).
In cold, dry conditions, the cement curing procedure is much slower. As an outcome, it generally runs out of water before it hardens even if the exact same amount of time was appropriate in warmer conditions.
How do I fix dry, soft and grainy render?
Gently saturate the rendered wall with water, making sure the render is totally wet and leave for 24 hours. After 24 hours, check the render and it ought to be more difficult than it was. Repeat the process of saturating with water to continue hardening if required. For DIY tips visit Cement Render Australia. Or alternatively Aus Renderers.
How can I conquer these problems?
Wet down masonry walls with low moisture or high suction and wait for the damp seek to decline off the wall prior to application of render. A coat of ROCKCOTE Keycote can be used prior to the application of cement render basecoat(s) to even more decrease suction. Offer it a heavy mist of water (may have to repeat the following day)if the cement render looks dry upon completion.
For more advice, or if you are still experiencing concerns, please contact the ROCKCOTE Technical Department on 1300 736 668.
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