Understanding how plastic shrinkage cracks form in new concrete and how proper curing prevents them

Outline

• Opening: Why cracks show up in concrete work, especially in hot, dry climates like Nevada.

• What plastic shrinkage is: moisture loss from the surface while the mix is still fresh and plastic.

• Why Nevada landscapes are a perfect storm: sun, wind, low humidity, and timing challenges.

• How to manage and prevent plastic shrinkage on site:

• Use curing compounds or moisture-retaining coverings

• Control evaporation: shade, wind breaks, misting, and proper scheduling

• Temperature control and proper curing duration

• Finishing considerations and curing practices

• Quick note on other processes: rapid cooling, excess moisture, and poor mixing—why they’re less likely to cause plastic shrinkage cracking but still important to know.

• Real-world tips for successful Nevada projects

• Wrap-up: keep moisture steady, plan ahead, and watch the weather

Plastic shrinkage cracks: the subtle enemy of fresh concrete

Let me explain the core idea in plain terms. When you pour concrete, the surface dries out quickly if the air is hot, the wind is brisk, or the humidity is low. The outer layer stiffens and starts to set while the inner portion is still in a plastic, workable state. That mismatch—outer surface shrinking faster than the still-plastic interior—pulls the surface in and can crack it. In our line of work, that’s not just a cosmetic headache; it can lead to water intrusion and uneven surfaces that complicate later landscaping steps.

Why this becomes a bigger issue in Nevada

If you’ve spent time on a Nevada job site, you know the weather can feel like a pressure cooker. Summer temperatures soar, the air is dry, and there can be a sharp breeze across paved areas. Even a slight gust can suck moisture from the surface in minutes. The result? Cracks appear sooner than you’d think, sometimes just hours after the pour. It’s not that the concrete is weak—it's that the moisture balance at the surface isn’t holding up as the rest of the mix still cures. And in heat-bleached landscapes, those cracks stand out like a sore thumb against pavers, gravel, or turf.

The science you need without the nerd voice

Here’s the essence: plastic shrinkage cracks form when the surface loses moisture too fast while the concrete is still plastic. The remedy is simple in idea, a bit trickier in practice: keep moisture at the surface while curing, and slow down evaporation. It’s about controlling the environment around the pour as much as it is about the mix.

Practical steps to keep plastic shrinkage at bay on a Nevada site

Think of curing as a protective blanket for the first 24 to 72 hours after pouring. You want that blanket to stay in place and keep the surface from drying out too quickly.

• Use curing compounds or moisture-retaining coverings

• A curing compound creates a translucent film that seals in moisture. It’s quick, it’s practical, and it travels well from job to job. If you’re in a hurry, you can also use moisture-retaining covers like plastic sheets or water-keeping fabrics. The key is to minimize evaporation from the top surface so the cement can hydrate evenly.

• In hot, windy conditions, you might layer: apply a curing compound first, then add a light covering if wind is ripping across the slab. It might feel like overkill, but it pays off in fewer cracks and a nicer finish.

• Control evaporation with shade and wind management

• Shield the pour from direct sun for the first 24 hours when possible. If you’re pouring in the heat of day, set up shade canopies or temporary windbreaks to slow down evaporation.

• Wind is sneaky. A breeze can pull moisture from the surface faster than you expect. A simple net or mesh barrier can make a big difference, especially on exposed driveways or pool decks.

• Evaporation retarders and careful curing timing

• Evaporation-retarding agents can be sprayed on the surface to reduce rapid moisture loss. They’re particularly useful on hot, dry days when the glassy crust forms quickly.

• Don’t rush the curing process. Keep the surface damp (or covered) for at least the initial 24 hours; extend that window in hot weather. If you’re unsure, err on the side of longer curing rather than shorter.

• Temperature management and finishing considerations

• Water used for mixing and curing should be cool, but not freezing cold. Sudden temperature shifts can shock the surface. In the desert sun, you’ll want to avoid placing a hot slab onto a cool ground layer that can increase stress at the top.

• When finishing, avoid aggressive troweling or finishing early in the cure window. A light, steady hand that doesn’t yank moisture to the surface will help keep the surface closer to the interior’s moisture level.

• If you’re using decorative finishes or exposed aggregate, plan for an extended curing period to let everything set evenly. A cracked surface will ruin the uniform look you’re trying to achieve.

• Scheduling and weather awareness

• In Nevada, forecast the day ahead. If possible, pour when the temperature is expected to be moderate and humidity relatively stable. Early morning pours can help, with cooling temperatures and lower evaporation rates. If you must pour mid-day, have a plan for rapid curing in place and be ready to cover as soon as the initial bleed water subsides.

• Surface design considerations that help

• Joint spacing, control joints, and proper slab thickness play a role in cracking overall, including plastic shrinkage cracks. Designing for a few extra joints in larger slabs can reduce stress concentrations.

• Textured finishes or light broom textures can mask small surface cracks if they do appear, giving you a more forgiving look while you address moisture control.

What about the other processes? They matter, but not as the primary driver for plastic shrinkage cracks

Sometimes other factors creep into the conversation, but for the specific issue of cracks caused by moisture loss in the plastic state, plastic shrinkage is the main culprit. Here’s a quick contrast:

• Rapid cooling of the concrete

• This can cause thermal cracking later in the curing process, especially if there’s a big temperature swing between day and night or if you place very cold water onto a hot surface. It’s a separate risk from surface moisture loss and tends to show up as cracks after the concrete has set more completely.

• Excessive moisture content

• If the mix is too wet, you’ll see other issues like color bleeding, segregation, or a weaker surface, but the immediate driver of plastic shrinkage cracks is surface moisture loss, not an overly wet mix.

• Poor mixing technique

• Without uniform mix, you can end up with inconsistent strength and finish, but crack causation in the plastic state is more about moisture balance than mixing quality. That said, a well-mixed, properly proportioned mix reduces other crack risks down the line.

Real-world tips from Nevada landscapes

• Always have a plan for summer pours. When the forecast calls for triple-digit heat, have an evaporation-control plan ready—shade tents, misting, curing compounds, and moisture-retaining covers staged and accessible.

• Keep a simple weather log on site. Note wind speed, humidity, and temperature at pour time. If conditions are changing rapidly, be prepared to pause or adjust your curing strategy.

• Train crew members to recognize signs of rapid surface drying: a glassy sheen, surface hairline cracking, or the first dry wisps along the edge. Early detection means you can apply coverage or re-wet the surface to slow evaporation.

• Use appropriate curing products for different projects. For driveways and patios that will be walked on or driven on soon after, curing compounds can be a fast safeguard. For decorative or high-visibility slabs, extra attention to shading and longer curing duration keeps the finish looking even.

• Include moisture management in your coordinate plan with other trades. If you’re pouring near irrigation lines or planting areas, consider how moisture from those activities might affect the surface during curing.

A quick on-site checklist you can print and keep handy

• Temperature and humidity check for the day

• Surface moisture level: is there a dry film or sheen forming?

• Curing method selected (compound, cover, or both)

• Shade plan in place (canopy, screen, or windbreak)

• Evaporation retardant applied (if hot and windy)

• Control joints and slab thickness reviewed

• Timeline for re-wetting or covering during the first 24 hours

Why mastering this matters for landscape professionals

Concrete that cracks in the early stage is not just a cosmetic blemish. It can complicate subsequent landscaping steps—installing pavers, laying sod, or setting grout lines for decorative concrete features. When you control plastic shrinkage, you’re protecting the surface integrity, reducing callbacks, and ensuring a durable base for the features your clients care about most.

A few words on approach and tone

If you’re reading this between boss calls and blueprint reviews, you’ll notice the message is practical: a plan, a few tools, and a watchful eye on the weather. It’s the kind of know-how that separates a good concrete job from a great landscape installation. You’ll get cleaner finishes, fewer surprises, and happier clients who notice the difference in the long run.

Final reminder: stay curious and keep the surface hydrated

Plastic shrinkage cracking is a predictable risk in dry, hot environments like parts of Nevada. The fix is straightforward: slow down evaporation, keep moisture on the surface during the critical early hours, and use curing strategies that fit the project and the climate. When you combine shade, proper curing, and sensible scheduling, you’ll reduce cracking and set a solid foundation for the rest of your landscape design.

If you’re on a job site and your crews are finishing a concrete slab under a blazing sun, remember this: it’s not just about pouring concrete. It’s about guarding moisture, guiding the cure, and letting the interior cure along with the surface. Do that, and the crack won’t stand a chance.