Alkali Resistance
The concrete mix is a high-pH environment (≈12.5–13). In this environment, organic pigments fade rapidly, whereas iron oxide–based inorganic pigments retain their chemical stability. In precast applications, the primary selection criterion is references belonging to the iron oxide family.
UV and Weather Resistance
Most precast panels serve outdoors for many years. The pigment's stability against UV radiation and freeze–thaw cycles is decisive for long-term visual performance.
- Red 110 / 130: widely used in exterior façade panels
- Yellow 920: a high-UV-stability alternative for warm tones
- Black 318: strong color yield for dark aesthetic targets
- Brown 686: for earth-toned architectural elements
Dosage and Strength Relationship
Pigment dosage should be kept within the range of 3–6% of the cement mass. Exceeding this range causes a decline in concrete strength, while going below it results in insufficient color saturation. The optimum dosage that delivers both the target color and mechanical performance is determined experimentally.
Color is not a decoration but a production parameter. It must be managed with the same discipline as the water/cement ratio.
Color Consistency
In precast production, castings are made in large batches. To keep color deviation between batches invisible, spectrophotometric matching of pigment batches and standardization of the mixing time are critical.
Cost Analysis
Cheap pigments mostly have low color efficiency (tinting strength), which requires increasing the dosage. Although high-quality pigments have a higher unit price, they provide an advantage in total cost. The decision should be made based on the pigment cost per m³, not the unit price.
Alba Pigment Recommendation
On precast concrete lines, when iron oxide red 110/130, yellow 920 and black 318 references—with high UV resistance and batch-to-batch ΔE < 1.0 stability—are used together, they deliver both aesthetic flexibility and economic balance.