PIGMENTS
PIGMENTS
Iron Oxide Pigments supplied by Acme Paving Consultants Pte Ltd (APC) are all colour stable. The pigments supplied by APC conform with the stringent requirements of British Standard Specification 1014:1975 (Pigments for Portland Cement and Portland Cement Products). Any colour changes noticed will be due to efflorescence and the general change in colour of concrete itself.
DOSAGE
The
dosage rate of the pigments is at the discretion of individual manufactures.
However, it is generally found that dosage rates of between 3% and 5% by weight
of cement will give the desired colours. Dosage rates above 7% are generally
not recommended.
In order to ensure complete uniformity of shade from one mix to the next, a standard procedure must be followed which involves measuring pigment quantities by weight and not by volume. All too often, mistakes are made when operatives use a scoop or shovel to determine the quantity of colour to add. Nearly always this practice results in an unacceptable degree of shade variation. The reason why this kind of variation occurs when volumetric measurements are made, is simple and is related entirely to pigment easily. A freshly made batch of pigment contains a certain amount of air whereas older stocks will become more compact on standing and lose the air content, giving rise to a heavier bulk density. Therefore equal volumes of new and older compacted pigment will not have equal weights.
Problems regarding pigment addition can be easily overcome by preweighing the colour before mixing and it is sensible to appoint a reliable operative to carry out this operation.
The amount of pigment needed to achieve the desired share will vary depending on whether a light or deep shade is required. Irrespective of whatever percentage is decided on, the calculation should always be based on the weight of the cement in the mix.
STORAGE
The pigments can be stored indefinitely providing the storage place is dry and
bags are kept off the floor on pallets or raised boards to prevent moisture
build up. No deterioration or loss of properties occur if these conditions are
met. Colouring materials stored in a damp atmosphere or on wet floors can absorb
moisture and if followed by a period of dry weather, hardening and lumping may
occur.
TECHNICALSERVICE
Quite often the customer can experience difficulties in achieving a desired
shade and needs advice or assistance will be pleased to give a full back up
service to customer. For advice on technical problems, please e-mail to us at
acmepaving@pacific.net.sg.
The technical advice given in good faith and to assist the user to achieve satisfactory and pleasing results. It does not imply any guarantee or warranty nor does it release the user from the obligation to thoroughly test the pigments as to their stability for the intended user or application.
Updated 24 July 2003
