1 kg = 3.80 €
Synthetic iron oxide red - 25 kg
Synthetic iron oxide, red, specially suited for colouring of cement, concrete, asphalt, screed, bricks, mortar and plaster, and for the production of abrasives. Sold in 25 kg bags.
Excellent quality, made in Italy.
Specifications:
|
Value |
Method |
|
|
|
Fe2O3 content |
95-97 % |
ISO 1248 |
Absolute density |
5 g/ml |
ISO 787/10 |
Bulk density |
0,6-1 g/ml |
ISO 787/11 |
Sieve residue (0,045 mm sieve) |
max. 0,2 % |
ISO 787/7 |
pH |
4-7 |
ISO 787/9 |
Soluble salts |
max. 0,5 % |
ISO 787/3 |
Oil absorbtion |
20-24 g/100g |
ISO 787/5 |
Heat stability |
200 °C 1 h |
SIOF 15 |
Light stability (1-8) |
8 (excellent) |
SIOF 14 |
Humidity |
1 % |
ISO 787/2 |
Concrete pigmentation
Iron oxides are water-insoluble pigments with a good alkali fastness and excellent light fastness. Considering these characteristics and their low price, they are considered the best pigments for concrete pigmentation. The quantity of pigment used varies usually from 3 % to 5 % of the weight of the cement since inerts do not take part in the pigmentation. A maximum limit of 7 % can be reached if a more intense colour is required without affecting the mechanical resistance of the finished product. In order to obtain the best final colouring it is preferable to mix the components in the following sequence: first of all inerts, then pigments and finally cement and water.
Variation of colour shade in time
When preparing coloured concrete it is extremely important to pay attention to the water/cement ratio of the mixture, ratio that affects the shade of colour. A brighter coloured finished product is obtained increasing the quantity of water but at the same time the mechanical resistaince and weather fastness is reduced. However in time the superficial layer of the finished products is subject to wear down which enhances the colour of the inert, consequently there is a change in the shade of colour independently from the pigments used.
Efflorescence
It is a physical-chemical phenomenon produced by the calcium hydrate which is in the cement and is water-soluble. It can occur during the drying process but also later when humidity occurs. In fact the calcium hydrate tends to migrate towards the surface of the finished product and, reacting with the carbon dioxide in the air, forms white patches of calcium carbonate which are more visible in darker colours. Iron oxides are insoluble in water and do not affect the above mentioned phenomenon, which can be reduced with the use of specific additives.The quality of the pigment, the right dosage of the components, the valid production technology and the use of additives are the basis of the best result in time of a coloured concrete finished product.