________ are used to press mortar and spread it uniformly.
Correct Answer: C. Floats
📚 Detailed Explanation: Floats — Surface Finishing Tool
Why C (Floats) is correct: A float is a flat, smooth surface tool used after screeding in the concrete finishing sequence. It is pressed down on the surface and moved in a circular or sweeping motion to embed aggregate, remove minor surface irregularities, and consolidate the surface layer, preparing it for the final troweling stage.
Concrete Surface Finishing Sequence
| Step | Operation | Tool | Purpose |
|---|---|---|---|
| 1 | Screeding | Screed board / darby | Strike off excess concrete; establish level surface |
| 2 | Floating | Floats (wood/bull float) | Press mortar, close surface, remove roughness from screeding |
| 3 | Troweling | Steel trowel | Final dense, smooth surface finish |
Types of Floats
| Type | Material | Size / Use |
|---|---|---|
| Hand float | Wood or magnesium | 60–90 cm; for small areas |
| Bull float | Aluminium or magnesium | 1.2–1.5 m wide; for large slabs from the edge |
| Fresno float | Steel | Long-handled; combines floating and light troweling |
Why the Other Options Are Wrong
| Option | Actual Use |
|---|---|
| Trowel | Final steel troweling for a hard, dense surface — step 3, not step 2 |
| Aluminium rod | Not a standard finishing tool for spreading mortar |
| Brush | Used for brooming texture on road surfaces; not for spreading |
- Floats press mortar and spread it uniformly — the second step in floor finishing after screeding.
- Floating is done while concrete is still soft but no longer plastic.
- Final step is troweling, which produces a hard, dense, smooth surface.