1. Types of Field Compaction Equipment

Let's start with smooth wheeled steel drum rollers. These rollers have a capacity ranging from 20 kN to 200 kN. Can anyone tell me what this capacity means in practical terms?

Does it refer to how much weight they can compact?

Exactly! A higher capacity indicates they can compact more material efficiently. They are self-propelled or towed. However, they are unsuitable for uniform sand, silty sand, and soft clay. Remember the acronym ‘GWS’ for Good with Sand – they work best with well-graded materials like sand and gravel.

Is there a specific type of soil they aren't good at?

Correct! They should not be used on loose sands or soft clays. Understanding the terrain is crucial for effective compaction.

So, if I want to compact a parking lot ground, would this be a good choice?

Yes, as long as the soil conditions are suitable. Remember to assess the soil type first!

In summary, smooth wheeled steel drum rollers are effective for compacting well-graded soils but not suitable for loose or soft soils.

Next, let's explore pneumatic tyred rollers. These rollers usually have two axles and carry rubber tyres. What might be the benefit of using tyres instead of solid drums?

I think they might provide better flexibility and adaptability over uneven surfaces.

Good point! They do provide better adaptability and can compact a range of soils, from coarse to fine. They require additional dead load, usually water, to reach between 100 to 400 kN in weight. This makes them effective across many soil types.

But what about when they're not effective? What kind of soils are they unsuited for?

They aren't effective on very soft clay and highly variable soils. Remember this – ‘CVS’ stands for Coarse, Variability and Soft clay.

Could you give an example of where to use these rollers?

Certainly! They would be ideal for compacting the base of a road before paving.

So, to recap, pneumatic tyred rollers are versatile and suitable for a variety of soils, but avoid using them on very soft clay.

Let's look at sheepsfoot rollers. What distinguishes these from the other types we’ve discussed?

They have those club-shaped feet, right?

Correct! The feet provide a kneading action, making them particularly effective for fine-grained soils. They can weigh between 50 to 80 kN. Do you recall which soils are best for them?

I think they are better for fine-grained and sandy materials with fines.

Exactly! They work well with fine-grained soil, sand, and gravel. However, specifics on their limitations are under revision. Always check the soil type before use.

When would I use a sheepsfoot roller in a project?

For applications such as road building where dense, fine soils are common. Just remember the term ‘FGB’ for Fine-Grained Benefits!

To summarize, sheepsfoot rollers are designed for kneading fine-grained soils and are very effective when compacting sand and gravel that contains fines.