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Efflorescence season – beware!

Late autumn is normally one of the 2 periods in the year when the phenomenon known as efflorescence becomes a major problem for concrete producers. Most efflorescence seen on concrete surfaces is unsightly and can be a problem for producers and clients alike.

Efflorescence is the formation of soluble calcium salts that have migrated to the concrete surface where it reacts with carbon dioxide causing the white salts to appear. The migration of the calcium salts to the surface is caused by the movement of moisture within the concrete to the surface and this is frequently encouraged to happen by the sharp changes in atmospheric pressure and humidity experienced in the UK during spring and autumn. 

Furthermore, it is widely reported that recent changes in cement production techniques and the new sources of raw materials being used in cement manufacturing has resulted in an increase in efflorescence.

Therefore in simple terms, the formation of efflorescence depends on 4 key things; the quantity of water in the concrete, presence of soluble salts in the cement, the migration pathway to the surface and the curing and storage conditions.

In attempting to control efflorescence there are several methods of reducing the potential for occurrence and Oscrete can help with both technical advice and specialist products in this regard. Oscrete has a range of products that can act to block the concrete pores thus limiting the moisture reaching the concrete surface that causes discolouration. Additionally, reducing the quantity of the mix water by using specially formulated admixtures can give significant benefits, as can concrete capillary sealing with highly mobile water repellents. Other actions, such as reducing cement content is possible with the use of Oscrete cement saving systems, and the use of controlled curing conditions to negate the atmospheric changes will frequently produce good results.

Oscrete technical staff has experience in dealing with concrete efflorescence issues and will be pleased to help our customers to find the right method in handling this problem. The use of Oscrete specialist admixtures and surface treatments can offer significant benefits to the concrete producer in minimising the causes of efflorescence.

Call the Oscrete Technical Department on 01274 393 286 for more information and advice on efflorescence control.

Oscrete Specialities

Fine chemicals for product manufacturers

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