Cold Weather Concreting

Cold temperatures present unique challenges, but concrete can still be placed successfully in winter. With the right planning—like heated enclosures, warm mix water, and accelerating admixtures—cold-weather pours can be done reliably. Speak to our team about best practices and product options for your winter pours.

Air Loss During Pumping

Air content can drop during pumping, especially through long booms or vertical lines. To reduce this:

• Keep discharge lines horizontal where possible

• Use flow-control devices on the pump hose

• Incorporate 90° elbows near the end of the line

• Loop rubber hoses when possible to minimize free-fall

• Check air content both at the truck and at the discharge point

Blistering

Blisters are often caused by early finishing, cold subgrades, or rapid surface drying. Reduce the risk by:

• Placing concrete on warmer subgrades

• Avoiding finishing too soon

• Using accelerators or heated environments in cool weather

• Keeping trowel blades flat during finishing

• Preventing premature surface sealing

Bugholes (Surface Voids)

Air pockets near formwork can be minimized by:

• Uniform vibration and spacing

• Placing concrete in lower lifts

• Keeping vibrators close to form edges

• Proper form release application

• Using self-consolidating concrete where possible

Crazing

Crazing is a network of fine surface cracks and is often due to poor curing. To avoid it:

• Begin curing immediately and keep surfaces moist

• Use continuous curing methods, not stop-start cycles

• Avoid adding cement dust to absorb bleed water

• Prevent surface drying during finishing with fog misting or retardants

Surface Crusting

Wavy or cracked surfaces often result from temperature differences or poor timing. Reduce this by:

• Keeping subgrade and concrete temperatures close

• Avoiding hot, windy placements

• Using retardants or fog sprays during finishing

• Delaying troweling until bleed water dissipates

• Using admixtures to control set times and consistency

Curling

Curling is the upward warping of slab edges. Prevent it by:

• Using proper curing methods and extending cure time

• Reducing water content and avoiding retempering

• Placing smaller slabs with closer joint spacing

• Increasing slab thickness or adding reinforcement

• Selecting shrinkage-reducing admixtures

Discolouration

Uneven colour is usually due to inconsistent finishing or curing. To minimize this:

• Time all finishing uniformly

• Avoid direct contact between plastic sheeting and the slab

• Use proper form-release agents and consistent curing techniques

Dusting

Dusting occurs when weak surface paste breaks down. Prevent it by:

• Never finishing while bleed water is present

• Starting curing promptly

• Avoiding extra surface water

• Venting heating units to avoid CO₂ contamination

Honeycombing

Voids inside walls or columns (honeycombing) result from poor vibration or rebar congestion. Prevent it by:

• Ensuring proper vibration depth and spacing

• Reducing congested reinforcement areas

• Using mixes with good flow and appropriate slump

• Considering SCC (self-consolidating concrete) for tight forms

Low Strength Results

Unexpectedly low compressive strength can result from improper field sampling or curing. To ensure reliable test results:

• Use certified technicians

• Maintain sample temperatures (15–25°C) onsite

• Store test cylinders in curing boxes

• Review each delivery ticket and follow water addition protocols

Plastic Shrinkage Cracking

These cracks occur early from rapid surface drying. Prevent them by:

• Erecting windbreaks and sunshades

• Fog misting to maintain surface humidity

• Dampening the subgrade

• Placing during cooler times of day

• Using synthetic fibres and evaporation retardants

Scaling

Surface flaking due to freeze-thaw cycles can be prevented by:

• Using air-entrained, 32 MPa concrete with proper water-cement ratio

• Curing concrete for at least 7 days

• Avoiding de-icers in the first winter

• Sealing concrete surfaces after 30 days of air drying

• Using wet curing during hot or dry conditions

Shrinkage Cracking

Uncontrolled cracking from drying shrinkage can be reduced by:

• Proper subgrade prep and drainage

• Choosing the right concrete mix for the job

• Planning joint spacing and reinforcement

• Initiating curing quickly after finishing

Mortar Flaking

Surface mortar flaking is linked to poor curing and drying. Avoid it by:

• Applying evaporation retardants between finishing steps

• Using wet curing methods during hot or dry periods

• Protecting the surface until curing begins

Popouts

Popouts happen when moisture enters the concrete and freezes around weak aggregate. Prevent them by:

• Using high-quality aggregates like limestone or hardstone

• Ensuring good surface drainage

• Curing properly and applying surface sealers

Want to avoid these issues on your next project?
Our team is here to help. Contact us to discuss mix options, admixtures, curing techniques, and custom solutions tailored to your job.