How Weather Impacts Compaction Efficiency

If so, you’re certainly not alone. Compaction efficiency isn’t just about the machine or material — weather plays a critical role too. Temperature, humidity and precipitation can all impact how well soil, asphalt or aggregate compacts, which means you as an operator may need to adjust your approach this spring to maintain performance and quality.

Key Takeaways

• Weather conditions like temperature, humidity and rain significantly influence how effectively soil and asphalt can be compacted.
• Adapting compaction techniques — including machine settings, timing of work and moisture control — is crucial for achieving optimal results in varying weather.
• Utilizing intelligent compaction technology allows for real-time monitoring and adjustments, leading to improved quality and longer-lasting stability.

If you operate asphalt rollers or soil compactors, here are some top tips to help you out.

How Weather Affects Soil and Asphalt Compaction Efficiency

A lot of us here at Volvo — including personnel at our North American Volvo dealers — get questions throughout the year about how weather affects compaction results. This is especially true during the wilder spring weather season. Below are a few of the top questions we get with answers that might help you out as well.

How does temperature affect asphalt compaction?

Extreme temperatures affect material behavior significantly:

• Cold temperatures can cause asphalt to cool and stiffen quickly, reducing your compaction time before they become unworkable. When this happens, it can prevent proper density.
• Hot temperatures can lead to excessive material softness, making it prone to over-compaction, rutting or instability.

What is the ideal moisture content for soil compaction?

First, it’s important to understand the concept of optimum moisture content (OMC), which is the ideal amount of water a soil must contain so that it can be compacted into a strong, safe and load-bearing surface. A good analogy here is making bread — there’s an ideal ratio of flour to liquid. If you have too much flour, the ingredients won’t bond together. If you have too much liquid, the mixture runs all over and has no structure. Soil compaction performs best at the OMC for the specific soil type, which for most soil types is generally between 8 and 18%.

Humidity can also play a factor in soil compaction, but more indirectly by impacting the moisture content of the soil:

• High humidity can increase moisture retention in materials, improving compaction for some soils but potentially making others too soft.
• Low humidity can dry out the material too quickly, reducing the binding effect needed for proper compaction.

Does rain affect soil compaction?
Rain can be a compaction killer:

• Light rain can be manageable for some granular materials but often reduces compaction effectiveness.
• Heavy rain saturates the material, preventing proper density and increasing the risk of material displacement or instability once compacted.

Best Practices for Adapting Compaction Techniques to Weather Conditions

Adjust Machine Settings and Passes
In cold weather, increase the number of passes and consider higher vibration frequencies to compensate for material stiffening. In hot weather, reduce vibration intensity to avoid over-compaction.

Timing Matters
Work during optimal weather windows when possible. Early mornings can be too cold, while midday heat can over-soften materials. Target moderate temperatures when you can for best results.

Control Moisture Content
For soil, aim for the optimum moisture content (again, generally between 8 and 18%). If conditions are too dry, a light water application can improve density. If it’s too wet, delaying compaction might be necessary to avoid poor results.

Choose the Right Compaction Equipment

• Drum selection: Smooth drums work best for hot mix asphalt in warmer conditions, while padfoot rollers are ideal for cohesive soils with higher moisture content.
• Vibration settings: Use lower frequencies for hot, soft materials — higher frequencies for cooler, stiffer ones.

Monitor and Adjust in Real Time with Intelligent Compaction Technology
Using onboard sensors with technologies like Volvo Compact Assist can provide real-time compaction data, helping you adjust speed, passes and vibration settings as conditions change.

Why It’s Important to Adapt

Failing to adjust for weather can lead to under-compaction (risking settling and instability) or over-compaction (causing material breakdown and structural issues). When you make the right adjustments, you help ensure:

• Longer pavement and soil stability lifespans
• Reduced material waste
• Fewer rework costs

Weather isn't just a challenge — it's a variable you can master. By staying aware of how temperature, humidity and precipitation affect compaction and then adjusting your techniques accordingly, you can achieve higher quality results, no matter the forecast.

If you’re looking for additional tips on asphalt and soil compaction, our 10 Fundamentals of Soil and Asphalt Compaction blog is a great start.