How to Lay In-situ Granolithic Concrete Flooring? [PDF]

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The granolithic concrete flooring is laid using rich concrete made with specially selected aggregate of high hardness, surface texture, and particle shape, which is adapted for heavy engineering factories, workshops, garages, warehouses, etc.

The granolithic concrete is chosen because of its high abrasion resistance and used for floor toppings wherever abrasion combined with impact is likely to be severe.

The granolithic concrete flooring can be laid in two different method-

1. Monolithically- The topping layer shall be laid within 3 hours of the laying of the base concrete.
2. Non Monolithically- The topping layer shall be laid after the base concrete is set.

Material for Granolithic Concrete Flooring

1. Aggregate

The aggregates used in the laying of concrete flooring shall consist of one or more of the following groups of aggregate-

1. Granite
2. Basalt
3. Trap
4. Quartzite.

The aggregates shall conform to respective country requirements, and the crushing value shall not exceed 30 percent.

2. Abrasives

Metallic or non-metallic materials of high abrasion resistance may be incorporated in the floor topping mix to increase the abrasive resistance of floor topping.

3. Surface Hardening Solutions

The surface hardening solutions recommended for use in the concrete flooring are sodium silicate, magnesium silico-fluoride, or zinc silico-fluoride or proprietary materials consisting mainly of one or more of these compounds.

Procedure for Laying of Granolithic Concrete Flooring

The laying of granolithic concrete flooring consists of mainly three parts, Sand Cushion, Base Concrete, and Topping Layer as shown in figure 2. The sand cushion and base concrete shall be laid as per the general laying procedure of conventional flooring methods. The laying of the topping layer for the granolithic concrete flooring is discussed below.

1. Laying of Granolithic Flooring over Base Concrete

1. The base concrete shall be laid in accordance with the specification.
2. While the newly laid base concrete is still green, the topping shall be placed in position as soon as possible but not later than 2 to 3 h of laying base concrete, depending upon the temperature and atmospheric conditions.
3. The base concrete at the time of laying the topping shall be still green but sufficiently firm to enable the workmen to walk over it by placing planks on its surface.
4. The granolithic mix (1:1:2) shall be deposited on the base concrete in the screed strips already laid and thoroughly compacted to the finished thickness.
5. The surface shall be tested to detect any undulation in the surface, if any, and shall be made good immediately.
6. The topping layer shall be floated with a wooden float to render the surface even, and after the surface is slightly hardened, it shall be finished smooth.
7. For flooring laid separately on hardened base concrete, the surface of the base concrete shall be thoroughly cleaned of all dirt, loose particles, laitance, etc. by scrubbing with coir or steel wire brush.
8. The surface shall be wetted with water for several hours, and surplus water shall be removed immediately before the topping is laid. 
9. A neat cement slurry shall be thoroughly brushed into the prepared surface of base concrete before laying the granolithic topping. 

2. Laying of Granolithic Flooring on Suspended Slab

1. The structural concrete shall be deposited in the forms thoroughly consolidated, and the surface shall be finished below the top edge of the desired floor level to accommodate the required thickness of the topping layer.
2. Any slope required in the floor finish to drain off water shall be given the structural concrete itself when it is still green.
3. The surface shall be finished smooth but rough enough to provide an adequate bond for the topping.
4. The granolithic concrete (1:1:2) shall be placed in position while the concrete is still green and immediately after the structural concrete has stiffened enough (but is still plastic) to allow the mason to tread over it by placing planks. 
5. The topping layer shall be thoroughly compacted and screeded to the finished grade with a float to render the surface even. 
6. For flooring laid over the hardened suspended slab, the surface of the base concrete shall be thoroughly brushed with a coir or steel wire brush to remove any scum or laitance before the topping is laid.
7. The surface shall be wetted with water for several hours and surplus removed by mopping immediately before the topping is laid.
8. A neat cement slurry shall be thoroughly brushed into the surface before depositing the topping. 

Sl No	Type of topping	Thickness of granolithic concrete floor topping in mm, min	Remarks
A	Floor topping laid over base concrete on ground
i)	Floor topping laid monolithically	20	Granolithic concrete floor topping shall be laid monolithic with base concrete.
	With base concrete
ii)	Floor topping laid separately on	40	Granolithic concrete floor topping shall be laid over separately prepared surface of set and hardened base concrete.
B	Floor topping laid over suspended slabs
iii)	Floor topping laid monolithic	20	Granolithic concrete topping shall be laid and finished monolithic with the suspended slab
iv)	Floor topping laid over hardened suspended slab	40	The granolithic topping shall be laid separately over the specially prepared surface of set and hardened concrete
v)	Floor topping laid over cushioning layer	40	Cushioning layer of lime concrete of 40 to 50 mm thickness shall be spread over the prepared surface of suspended slab. Topping shall be laid as in Sl.No. (iv)

Curing and Maintenance

The flooring surface shall be kept moist at least for ten days, and no traffic shall be permitted on the surface during this period.

For proper maintenance of granolithic flooring, frequent washing of the surface with water may be sufficient to keep the floor finish in a clean condition. Any grease stains may be removed using sodium metasilicate, caustic soda, some phosphates, or other proprietary materials.

FAQs on Granolithic Flooring

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2. How to Pour Concrete Over-Existing Concrete Slab?