Which floor with a concrete base is spread and levelled with 5 to 8 cm thick lime-surkhi mortar?
🔬 Understanding Floor Bedding Mortars
The type of mortar used as a bedding layer beneath the final flooring surface is crucial to the floor's construction and final properties. Lime-surkhi mortar is a traditional, breathable, and flexible mortar made from lime and finely powdered burnt brick (surkhi). Its specific thickness is characteristic of certain traditional flooring methods.
Mosaic flooring is a decorative type made from pre-cast concrete tiles with marble chips on the top surface. The construction process for this type of flooring specifically involves laying a thick, 5 to 8 cm layer of lime-surkhi mortar over a concrete base, into which the tiles are set.
⚖️ Detailed Analysis of Different Floor Types
Let's examine the construction methods for each type of flooring.
(a) Terrazzo floor
Why it's incorrect: Terrazzo is a poured-in-place floor. It consists of marble, quartz, or granite chips mixed with a cement or polymer binder. This mixture is applied over a concrete base, but it does not use a thick lime-surkhi mortar bed. The final surface is ground and polished to expose the aggregate.
(b) Granolithic floor
Why it's incorrect: Granolithic flooring is a heavy-duty topping made from rich concrete with hard, specially selected aggregates. It is applied directly over a concrete base and is designed for industrial environments like factories and warehouses. It does not involve a lime-surkhi bedding layer.
(c) Mosaic floor
Why it IS the correct answer: The defining construction method for a traditional mosaic floor is the use of a thick 5 to 8 cm lime-surkhi mortar bed over the concrete base. The pre-cast mosaic tiles are then pressed into this mortar bed, which is allowed to set before the surface is ground and polished. This specific detail matches the question perfectly.
(d) Flagstone
Why it's incorrect: Flagstone flooring uses large, flat stones (laminated sandstone). These are typically laid over a 10 to 15 cm layer of lime concrete, and the stones themselves are set on a thinner 20 to 25 mm (2 to 2.5 cm) layer of bed mortar, not a thick 5 to 8 cm lime-surkhi base.
📋 Summary of Floor Construction
- Mosaic Floor: Uses pre-cast tiles set into a thick 5-8 cm lime-surkhi mortar bed.
- Terrazzo Floor: Poured-in-place mixture of cement and decorative chips; does not use a lime-surkhi bed.
- Granolithic Floor: A hard concrete topping for industrial use; applied directly to the base.
- Flagstone Floor: Natural stones laid on a thin layer of bed mortar over a lime concrete sub-grade.