WO1981003676A1 - A method in connection with formwork/casting and a means and arrangement for carrying out said method - Google Patents

Abstract

In connection with formwork for concrete walls form ties are protected by a hollow plastic cone having a through boring. After setting of the concrete said plastic cone is knocked out of said concrete and the remaining hole is sealed by a cone made from lightweight concrete and provided with a glue. For the production of said lightweight cones an expanded plastic mould provided with a number of long conical cavities is used.

Description

AMETHOD INCONNECTIONWITHFORMWORK/CASTINGAND

AMEANSANDARRANGEMENTFORCARRYINGOUTSAIDMETHOD

In connection with formwork for concrete walls by large sheet forms ties are used to maintain the spacing of forms. To prevent adhesion between the concrete and said ties, the ties are protected by plastic tubes or bushings which may have a circular or rectangular shape.

When the concrete mix has set, the forms are removed and said ties are pulled out of said protective plastic tubes, which are, however, left in the concrete. The holes formed by said plastic tubes are grouted from both sides with a suitable cement grout, which is quite a time consuming operation. Also, it is often difficult to fill said holes completely, which may inter alia result in sound transmission. In some steel forms steel cones are used in stead of plastic tubes for tie protection. When the concrete mix has set, said cones are knocked out of the wall and the remaining holes are filled with concrete grout or concrete cones. The above mentioned methods are either too expensive or not satisfactory.

A new method has now been developed, whereby the mentioned disadvantages are avoided and which is considerably less expensive and more labour saving than the known methods. The new method also results in walls that satisfy the requirements as regards decibel transmission. These objects are achieved in the following mannert In stead of plastic tubes and steel cones a plastic cone is used, which is reusable and considerably more lightweight than a corresponding steel cone. Plastic cones may be used with all kinds of forms, in contrast with steel cones which deform plywood forms when used in connection with them. By using a suitable plastic material for the cones it is possible to obtain cones that are easily extracted from the set concrete, that are sufficiently soft not to destroy the form, and at the same time strong enough to withstand the stresses they are subjected to during casting.

In stead of a concrete cone a cone of set aeroconcrete is used Aeroconcrete is a fluid, foaming cement mix requiring water tight moulds.

For the production of said concrete cones a non-cracking aeroconcrete mix is used with water tight insulating moulds.

For the water tight and heat insulating mould for said aeroconcrete an expanded plastic mould is used. Due to the excellent insulating properties of expanded plastic the temperature is easily controlled during setting, which results in a more uniform quality of the set and finished cones. A preferred embodiment may comprise an expanded plastic block having a number of holes of the desired diameter and shape drilled out or otherwise prepared, so as to enable moulding of several cones in one block. Such an expanded plastic block being comparatively inexpensive, it may also serve as a transport packing for the set cone blanks. Another advantage of moulding said lightweight concrete cones in a mould as mentioned is that the length of the finished cones is easily obtained by cutting or sawing the entire combination of set or substantially set cone blanks and their mould to correct size. Since said cone blanks lie partly restricted in their mould, a large number of cones may be cut sawed through to the desired length in one single operation. In this manner it is possible to produce cones having lengths that are exactly adapted to the actual wall thickness. According to the novel method and with said novel cones the plastic cones having longitudinal holes are inserted into the form before casting and the ties are run through said cones and are secured to the form in a manner known per se. After setting of the concrete, said forms and ties are removed and said plastic cone is knocked out by the aid of a suitable tool. Aeroconcrete cones of an adapted length are provided with a suitable glue and are inserted into the holes where plastic cones have been removed. Aeroconcrete being relatively soft, it can optionally be secured by nails, cut to size or prepared otherwiese.

Claims

Claims:

1. A method in connection with formwork/casting of concrete walls, wherein form ties are protected by prearranged hollow plastic elements, and wherein the forms and ties are removed when the cast has set and the remaining holes are sealed, c h a r a c t e r i z e d i n that a plastic cone having a through boring is used for a protective plastic element, said plastic cone being removed after setting og the concrete and the remaining hole being sealed by a cone of aeroconcrete provided with a glue.

2. A method for the production of an aeroconcrete cone for use in the method as stated in claim 1, c h a r a c t e r i z e d i n that the liquid lightweight concrete comprises usual adjuvants, is cast in an expanded plastic mould provided with a number of elongated conical cavities the size and shape of which substantially correspond to those of the used plastic cones.

3. A method as stated in claim 2, c h a r a c t e r i z e d i n that the mould containing set or substantially set lightweight concrete cone blanks is cut across the longitudinal axis of said cones for adjusting the length of said cones.

4. The utilization of an expanded plastic block provided with a number of conical cavities both for a casting mould for lightweight concrete cones and for a transport packing for said cones.