Concrete Pigment

Color charts and codes are based on pounds of pigment per 94 lb (43 kg) of cement mate-rial, including Portland cement, silica fume, fly ash and lime. Sand and aggregates are not used in this ratio. The maximum level of pigment to cement is 10% by weight. Using less than 1% pigment can result in a washed-out appearance. Blue pigments should be mixed dry with any cement-based material to ensure even color distribution.

When an exact color match is required, complete a test pour, mixing the exact ingredient and ratios that will be use onsite. When custom blends are made for countertops, ready mixes, overlays, curbing, mortar, grouts and other cement based products, the colors hold true within an acceptable range to most users, especially when the mixture has been adjusted to meet specification needs of the mix and the project application

For a standard mix, the simplest method to convert the values on the color chart to a specific pour is to multiply the poundage on the chart by 5 to determine how much pigment per yard is needed. Consistency with the pigment per yard ratio is critical in achieving matching pours. The water level and mix ratios in each load are critical as well. It is essential to know how much concrete is in the truck, not just how much will be poured.

Dispense the pigment in the back of the truck, using the hose to clean the fins and ensuring that no loose pigment remains to cause streak-ing. Spinning the mix for 10 – 15 minutes is gener-ally sufficient to properly disperse the pigment. Place and work the concrete as normal.

As the concrete sets, the color will appear to fade. This is caused by the concrete dispensing powder on the surface and will be resolved by sealing this in the same way as a decorative concrete would be sealed. Once sealed, the color should be stable and considerably darker than at first appearance pre-seal.

• Use the same brand of cement aggregates and sand, as well as the same cement to pigment ratio until project completion.
• In order to avoid undesired discoloration do not use calcium chloride as a set accelerator
• Difference in slump may produce a noticeable difference in color between batches
• Use local exhaust or bag-house for ventilation
• If material is release or spilled, scoop or vacuum the floor and wash with water
• To avoid color variation, be consistent in all stages of the batching mixing, forming/placing and hardening of concrete

• Ensure that the aggregate-cement ratio is sufficient to enable the cement paste to completely fill the voids between the aggregate particles after compaction
• To minimize air voids that remain after cement hydration, add the concrete mix only to the minimum amount of water needed to achieve required work-ability
• Select sands and aggregates for the mix design carefully, as appropriate particle size and shape can help to improve mechanical compaction, effectively squeezing air voids and allowing them to be replaced with the cement paste
• Use local exhaust or bag-house for ventilation
• If material is release or spilled, scoop or vacuum the floor and wash with water
• To avoid color variation, be consistent in all stages of the batching mixing, forming/placing and hardening of concrete