1.1.3. Suitable for well graded sand, gravel, silt of low plasticity

Today, we will start by discussing smooth wheeled steel drum rollers. They have capacities ranging from 20 kN to 200 kN. Can anyone tell me what types of soil they can effectively compact?

Are they good for well graded sand and gravel?

Exactly, Student_1! They are suitable for well graded sand, gravel, and silt of low plasticity. Remember the acronym WGS for Well Graded Soils!

What about uniform sand or soft clay?

Great question, Student_2. These rollers are actually unsuitable for uniform sand, silty sand, and soft clay. Why do you think that is?

Maybe because they can’t penetrate those types effectively?

Right! Their weight and action are not designed for penetrating softer soils. Let's remember, WGS for smooth wheel applications but not for soft soils!

What’s the main purpose of using these rollers?

The main purpose is to create a denser soil structure that is essential for construction stability. Nice engagement today! Recapping: Smooth wheeled steel drum rollers are WGS suitable, ineffective on soft soils.

Next, we move on to pneumatic tyred rollers. Can someone describe their common features?

They have two axles with rubber wheels, right?

Exactly! They usually have two axles and can carry weights up to 400 kN by adding water. What types of soils can they compact?

They can compact most coarse and fine soils.

Correct, Student_2! But they are ineffective on very soft clay. Remember, PWTS: Pneumatic for all soils excluding soft clay.

So, why do they need water?

Good question, Student_3. Water increases their dead load, allowing for better compaction. Heavy loads compress the soil better.

What would you recommend for soft clay, then?

In that case, sheepsfoot rollers would be a better option! Always consider soil properties before selecting equipment.

Finally, let's discuss sheepsfoot rollers. What do you know about how they operate?

They have drum fitted with feet that kneads the soil, right?

Exactly! This kneading action is excellent for compacting fine-grained soil. They typically weigh between 50 to 80 kN. What’s their suitability?

They work well with fine-grained soil and gravel with fines.

Yes! Remember FS for Fine Soils with Sheepsfoot rollers. However, they are also unsuited for certain soil types. Can anyone guess which?

Is it coarse gravel?

They might handle some coarse gravel, but they struggle with uniform sand and very coarse soils. Their kneading action supports heavy compaction effectively on fine materials.

So for varying soil textures, we need to carefully choose the compactor?

Precisely! Always assess the soil and compaction needs before selecting equipment. Well done today! Let's recap: Sheepsfoot rollers are FS suitable for fine materials but tricky with coarse.