Basics in Building Construction

Building Components And Types

Lesson 20 : Ground Floors

Common Flooring And Their Construction

Mosaic Or Terrazzo Flooring

This is a most commonly used type of flooring, but costs high when compared to plain cement concrete flooring. It is elegant in appearance, possesses smooth and glossy finish and easy to clean. The mosaic floor consists of two layers; The bottom layer is of cement concrete 1:2:4 laid to a thickness of 20 to 25 mm and the wearing layer is of cement and marble chips ' mixture of proportion 1: 5/or 1 1/2 (Cement: marble chips) laid to a thickness of 6mm.

Method of Construction

1. The sequence of operations of preparation of sub base, and laying of base concrete are carried out in the same manner as in the case of cement concrete flooring.
2. Similar to cement concrete flooring the entire floor area is divided into suitable panels by using aluminium or glass strips. The main intention behind, providing these panels are not to allow the 'floor to crack due to shrinkage. Alternate panels should be cast in alternate days.
3. The surface of lean cement concrete base should be cleaned of all dirt, dust, mortar droppings etc. and should be wetted with water. Then the surface is given a wash of neat cement slurry.
4. The bottom layer of cement concrete 1:2:4 is laid to a thickness of 20 to 25 mm, consolidated, levelled and finished to/ a slightly rough surface. When, this surface is sufficiently hardened,/the wearing layer of cement, marble chips mix. Is laid' to a thickness slightly greater than the specified and the, surface is floated and trowelled.
5. The surface should be covered with wet gunny bags and left undistur­bed for 2 days. The surface shall then be ground with sand stone and all loose scales of cement is removed. A neat coat of cement slurry is applied and left for 6 days, duly curing by water ponding.
6. After 6 days, the surface should be ground with carborandum stones of different grades starting from coarse one and successively with finer ones, and the rubbing is continued until the entire surface shows a. uniformly granular appearance. The surface should be kept wet ' during all these days.

Finally the surface is rubbed with oxalic acid powder to get a glossy finish