Why is Concrete Grey? (Can It Be Other Colors?)

Why is Concrete Grey? Can It Be Other Colors?

Concrete is grey because cement—its binding ingredient—is naturally grey. But concrete can definitely be other colors. Understanding why it's grey and how to change the color helps you choose the right approach for your project.

Why Concrete Is Grey

Concrete gets its grey color from cement, which is naturally grey.

Cement's Natural Color

Portland cement (the most common type) is grey because:

• Raw materials: Made from limestone, clay, and other materials that are naturally grey
• Manufacturing process: Heating and grinding produces grey powder
• Iron content: Contains iron compounds that create grey color

How Cement Colors Concrete

Since cement is the binder that holds everything together:

• Dominates color: Cement paste determines the overall color
• Covers aggregate: Fine cement particles coat the aggregate
• Grey appearance: Results in grey concrete

Method 1: Integral Pigments (Mixed in Truck)

Integral pigments are added to the concrete mix during batching, creating color throughout the concrete.

How They Work

Integral pigments:

• Added during mixing: Mixed into the concrete at the batch plant
• Distributed throughout: Color is uniform throughout entire depth
• Permanent: Color is part of the concrete, won't fade or wear off
• Many colors available: Browns, tans, reds, blacks, and custom colors

Application Process

1. Specify color when ordering: Tell your ready-mix supplier the color you want
2. Supplier adds pigment: Mixed into concrete during batching
3. Place concrete normally: No special application needed
4. Color is permanent: Built into the concrete

Advantages

• Permanent: Color won't fade or wear off
• Uniform: Same color throughout entire depth
• No special application: Just place concrete normally
• Scratch-resistant: Color goes all the way through

Cost

Integral color adds approximately $2-$4+ per square foot to concrete cost, depending on color and project size. Actual costs vary.

Method 2: Surface Hardeners

Surface hardeners with color are applied to the surface of wet concrete during finishing.

How They Work

Colored surface hardeners:

• Applied to wet concrete: Sprinkled or broadcast onto surface during finishing
• Worked into surface: Troweled or floated into the top layer
• Create surface color: Color is in the top 1/8 to 1/4 inch
• Permanent: Become part of the surface layer

Application Process

1. After screeding: Apply when concrete is ready for finishing
2. Broadcast material: Sprinkle evenly across surface
3. Work into surface: Float or trowel to work it into the top layer
4. Finish normally: Continue with normal finishing process

Advantages

• Permanent surface color: Becomes part of the surface
• Increases surface hardness: Hardeners also strengthen the surface
• Dust-proof: Reduces surface dusting
• Many colors available: Various color options

Limitations

• Surface color only: Color is only in the top layer
• Can wear: If surface wears significantly, color may fade
• Requires skilled application: Needs proper technique

Method 3: Stains (After Concrete Cures)

Concrete stains can be applied to cured concrete to change its color.

How They Work

• Penetrate concrete: Go into surface pores
• Chemical reaction: Create permanent color
• Applied after curing: Can be done on existing concrete

Color Options Available

You can achieve many colors:

• Browns and tans: Earth tones, popular for natural look
• Reds and terracotta: Warm, vibrant colors
• Greens and blues: Less common but available
• Blacks and charcoal: Modern, dramatic look
• Custom colors: Many suppliers can create custom colors

Which Method to Choose

Integral pigments: Best for new construction, permanent color throughout, most durable

Surface hardeners: Best when you also want increased surface hardness and dust-proofing

Stains: Best for changing color of existing concrete

The Bottom Line

Concrete is grey because cement is naturally grey. But you can definitely have colored concrete. Use integral pigments (mixed in the truck) for permanent color throughout the concrete, or surface hardeners for surface color that also increases hardness. Both methods create permanent color that won't fade. For existing concrete, use stains to change the color after it cures.

Colored concrete adds visual interest and can complement your design. Choose the method that works best for your project and timeline.

Interested in colored concrete? Contact Local Concrete Contractor. We can help you choose colors and methods that work for your project.