FORM WORK

INTRODUCTION

When the concrete mixture is mixed with water it is at the liquid composition. At that time it is not a dense solid, before initials setting of cement. There for it is necessary to provide supports to held and gain the required shape. These temporary constructions, which are provided to keep the required shape of concrete, are called formwork.

When constructing formwork following things must be considered,

1.     The formwork should be strong enough to bear the load of reinforcement and wet concrete.

2.     It should not be curved because of the movement of working people and equipment’s.

3.     It should be erected correctly to get the required shape safely.

4.     The joints should be welled fixed avoiding grout leakages.

5.     Formwork should be constructed as to be easily dismantled and removed in sections in the desired sequence from the cast concrete, without shock, disturbance or damage.

Timber is the most widely used material for formwork. But steel formwork is also used and the finish is pleasing.

 MATERIAL USED FOR FORMWORK.

·        TIMBER

This is the most common material used for formwork construction. It is easy to work with and is also cheap. The moisture content of timber should be between 15%- 20%. So if the timber is dry, it will absorb moisture from the wet concrete that could weaken the resultant concrete member.

·        PLYWOOD

Strong thin board made by gloving layers with the direction of grain alternative. Plywood is widely used to construct formwork because it is strong; light weighted and supplied in easy handling sizes. The plywood sheet sizes available at site are 900mm x 2400mm and 1200mm x 2400mm. The thicknesses of plywood sheets are 12mm,10mm or 18mm.

·        STEEL

Steel also widely used material for constructing formwork nowadays. The smooth surface of steel is helpful to remove formwork easily and the concrete surface is pleasing and finished smooth. Steel formwork is strong enough to bare the load of the concrete & it is no doubt about the strength. Although the strength and finishing surface is much more it is somewhat difficult to handle the steel shutters. This is because of the weight of the large steel formwork. In our site we use steel plates to construct coloumns. They are called Docka plates and the procedure of that system is called Docka system.

DOCKA SYSTEM

It is a modern formwork system extreamly durable and robust made with hot dip galvanization. It is very strong and takes heavy loads. Docka specially easy and manufactured by experienced specialists. There are variable hights of  Docka plates. There is a Docka factory in Europe. Tabelforms load towers and even stairs towers can be constructed with it and for upper construction and supporting structure for every  height.There are 0.9, 1.2, 1.8m, heights. Concrete walls can be constructed easily.