Data centers are among the most demanding concrete environments built today.
Unlike commercial floor slabs, data center floors must withstand:

• Concentrated rack and point loads

• Ultra-tight FF/FL tolerances for automated equipment

• Sensitive resinous and ESD flooring systems

• Strict limits on vibration and slab movement

• Zero tolerance for unexpected shutdowns

In these facilities, “normal” shrinkage or hairline cracking isn’t cosmetic—it can compromise uptime, equipment performance, and flooring integrity. The challenge is that the very mix designs used to achieve higher performance (low water-to-cement ratios, high strength, and lower permeability) are also the ones most susceptible to autogenous shrinkage, self-desiccation, and internally generated stress.

Traditional surface curing methods do not solve this issue because the problem begins inside the concrete, not at the surface.

Internal curing technologies—including nano-silica admixtures such as E5® Internal Cure—are designed to help stabilize moisture throughout the slab depth, making high-performance data center floors flatter, more stable, and more predictable long-term.

What Shrinkage Really Is—and Why Data Centers Feel It More

Concrete experiences two main forms of shrinkage:

1. Drying Shrinkage

Moisture leaves the slab and evaporates into the environment, causing the surface to contract.

2. Autogenous Shrinkage

The cement is consuming water during hydration, and internal relative humidity drops—even if the slab is sealed.

Low w/c mixes used in data centers begin with very little free water. As hydration progresses:

• Capillary pores empty

• Internal RH drops

• The cement paste contracts

• Internal tensile stress builds

This shrinkage often presents as:

• Random cracking between joints

• Joint widths widening beyond design intent

• Curling or warping at slab corners

• Loss of FF/FL

• Higher deflection under load

Data center slabs are especially vulnerable because:

• They are thicker (which makes re-wetting nearly impossible)

• They contain dense reinforcement

• They support higher, concentrated loads

• They often require precision-level flatness

That means shrinkage isn’t just undesirable—it is a direct threat to operations.

Why Surface-Only Curing Can’t Control Internal Shrinkage

Traditional curing attempts to slow evaporation at the surface:

• Water spraying

• Wet blankets

• Curing compounds

These methods help with drying shrinkage, but do little for autogenous shrinkage, which occurs deep within the paste.

Once internal water is consumed:

• Hydration slows

• The microstructure becomes stressed

• The slab shrinks from within

• Volume change becomes uneven

And because thick data center slabs cannot be effectively re-wetted from the surface, hydration remains incomplete and stress continues to build.

This leads to:

• Higher permeability

• Unhydrated cement

• Micro-cracking

• Curling and warping

• Long-term dimensional instability

Surface curing protects the top ⅛–¼ inch.
The structural behavior of the slab comes from the other 99%.

Internal Curing: A Built-In Water Reservoir for High-Performance Concrete

Internal curing addresses shrinkage at its source by storing curing water inside the concrete and releasing it only when the cement needs it.

Internal curing admixtures—such as the nano-silica system used in E5® Internal Cure—help control both:

• The water of transport (excess water needed for placement)

• The water of convenience (water needed for hydration)

By managing these internal moisture phases, internal curing supports hydration throughout the slab depth. Benefits include:

• More complete hydration

• Reduced autogenous shrinkage

• More uniform internal RH

• Less curling at joints and slab edges

• Lower permeability

• Fewer micro-cracks

According to the E5® Internal Cure technical documentation, this process can also eliminate the need for wet curing and topical curing compounds while supporting deeper hydration and reducing drying shrinkage.

For data center slabs, this micro-level moisture control is essential.

From Internal Moisture to Internal Stress Relief

Shrinkage is a function of internal stress.
Internal stress is a function of internal water availability.

When hydration consumes water faster than it can be replenished:

1. Capillary tension forms

2. Pore structure contracts

3. Autogenous shrinkage increases

4. Tensile stresses accumulate

5. Micro-cracking, warping, and curling occur

Internal curing reduces this chain reaction by maintaining internal humidity, helping the slab hydrate more uniformly with less volumetric strain.

The result?

• Reduced shrinkage

• More dimensional stability

• Less joint widening

• Better long-term FF/FL retention

Field data and independent research have shown that internal curing can significantly reduce shrinkage-related performance issues in dense, low w/c concretes commonly used in heavy-load environments.

Why This Matters So Much for Data Centers

Shrinkage isn’t just a materials-science issue.
In data centers, it directly impacts:

1. Rack Stability

Joint movement or curling can cause rocking, differential deflection, or out-of-tolerance point loading.

2. FF/FL Requirements

AGVs, dense racking systems, and laser-guided equipment demand extremely tight tolerances.

3. Specialty Floor Systems

ESD, epoxy, and resinous flooring are highly sensitive to cracks, pH, moisture migration, and surface movement.

4. Operational Uptime

Repairs often require shutting down sections of the facility—unacceptable in mission-critical environments.

Internal curing helps reduce these risks by limiting shrinkage from the inside out, stabilizing slab geometry, and supporting more predictable long-term performance.

Paired with surface-level moisture and pH control strategies (such as those provided by Catalyst-type nano-silica treatments), internal curing supports the full flooring assembly—not just the concrete substrate.

FAQs: Shrinkage, Internal Curing, and Data Center Slabs

1. What’s the difference between autogenous and drying shrinkage?

• Drying shrinkage: moisture leaves the slab to the environment.

• Autogenous shrinkage: hydration consumes internal water, lowering internal RH.
  Internal curing primarily targets the autogenous component.

2. Does internal curing replace wet curing?

Some internal curing admixtures—such as E5® Internal Cure—are designed to eliminate wet curing and traditional curing compounds while still retaining moisture for hydration.

Good placement and protection practices still apply.

3. Is internal curing backed by research?

Yes. Internal curing has been documented extensively in academic literature, including studies validating shrinkage reduction, hydration efficiency, and improved dimensional stability. E5®-related research includes independent lab verification and DOT testing programs.

4. Will this help with ESD and resinous flooring systems?

Reducing shrinkage and improving internal moisture uniformity helps stabilize flooring substrates. This supports long-term adhesion and reduces movement-related failures.

The Bottom Line

High-performance data center slabs require more than surface curing.
Low w/c mixes are inherently prone to autogenous shrinkage because the internal moisture supply is limited. The most serious stress and cracking issues begin inside the concrete, long before surface curing can help.

Internal curing provides a built-in moisture reservoir that supports hydration from within, reduces shrinkage, and stabilizes the slab for long-term performance.

Nano-silica–based systems like E5® Internal Cure are examples of how internal curing can be integrated into modern mix designs to help data center floors remain flat, stable, and reliable over decades—not just years.

Next Step for Concrete Professionals

Download the Engineering Package

Access mix design recommendations, internal curing specifications, testing data, and the complete submittal package to support high-performance data center slabs.

Inside, you’ll find:

• Internal curing requirements for low w/c, mission-critical slab designs

• Guidance for reducing autogenous shrinkage and internal stress

• Documentation on moisture management and pH stability

• Verification testing and ASTM references

• Support resources for FF/FL, shrinkage control, and slab durability

Need project-specific guidance?

Speak With a Technical Representative

If you’d like to review mix design parameters, loading criteria, or curing strategies for an upcoming data center project, connect with a technical specialist to discuss possible solutions.