1964-03-04

Abstract of GB951035 951,035. Moulding porous concrete. YTONG INTERNATIONAL A.B. Sept. 12, 1962, No. 34844/62. Heading B5A. Lightweight concrete is cast in stages, each stage being made porous and allowed to set before a further amount of concrete is cast on top of it. After a casting has set the surface of it is roughened, and is wetted before the next casting is applied or has a concrete mixture containing excess water cast on to its surface.

4

1964-03-04

B28B1/16 ; B28B1/50 ; B28B1/16 ; B28B1/50

B28B1/16 ; B28B1/50

GB19620034844 19620912

GB19620034844 19620912 ; FR19630942290 19630723

BE625023 (A)

1	A method for the casting of lightweight concrete blocks
	Inventor:	Applicant:
	EC:B28B1/16; B28B1/50	IPC: B28B1/16; B28B1/50;B28B1/16(+1)
	Publication info: BE625023 A - 0000-00-00
2	Procédé pour couler des blocs de béton léger
	Inventor:	Applicant: YTONG INTERNAT AKTIEBOLAG
	EC:B28B1/16; B28B1/50	IPC: B28B1/16; B28B1/50;B28B1/16(+1)
	Publication info: FR1373715 A - 1964-10-02
3	A method for the casting of lightweight concrete blocks
	Inventor: ANDERSSON GORDON	Applicant: YTONG INTERNAT AKTIEBOLAG
	EC:B28B1/16; B28B1/50	IPC: B28B1/16; B28B1/50;B28B1/16(+1)
	Publication info: GB951035 A - 1964-03-04

WHAT WE CLAIM IS:-

1. A method for casting lightweight concrete, characterised in that such a quantity of lightweight concrete mass is first cast into a mould of predetermined size that after being made porous the mass has an almost even porosity, the mass then being permitted to set 40 for so long a time as to withstand a subsequent casting of an additional layer on top of it, and as a second step, such a new quantity of lightweight concrete mass is cast on the previously cast and set one, that it is 45 made substantially evenly porous and is left to set, this procedure being repeated until the desired height of the cast lightweight concrete is reached.

2. A method according to Claim 1, characterised in that the surface of the cast, already porous and stiff layer is made rough before the next layer is cast thereon.

3. A method according to Claim 1 or 2, characterised in that water is poured on the 55 surface of the cast, already porous and stiff layer before the bginning of the next casting.

4. Lighweight concrete when produced by the method claimed in any preceding claim. 60 For the Applicants, F. J. CLEVELAND & COMPANY; Chartered Patent Agents, 29 Southampton Buildings, Chancery Lane, London, W:C.2.

Berwick-upon-Tweed: Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd.-1964 Published at The Patent Office, 25 Southampton Buildings, London, W.C.2. from which copies may be obtained.

PATENT SPECIFICATION

4'; Inventor: GORDON ANDERSSON.

: '> F 1Date of Application and filing Complete Specification: September 12, 1962.

mI) it.Complete Specification Published: March 4, 1964.

- ) Crown Copyright 1964.

Index at Acceptance:-B5 AIRSD.

International Classification:-B 28 b.

COMPLETE SPECIFICATION

NO DRAWINGS A Method for the Casting of Lightweight Concrete Blocks We, YTONG INTERNATIONAL AKTIEBOLAG, a Swedish Body Corporate of Lagerlofsgatan 8, Stockholm K, Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:In the lightweight concrete manufacture distinction is made between such lightweight concrete as is made porous before being cast and such lightweight concrete which is made porous after casting. For the latter type, it has been possible to attain only a limited height to which the mass has been allowed to rise during the forming of the pores and which never surpassed a maximum figure of about cm, otherwise the mass became too great to be evenly aerated or to retain even porosity.

Up to now, however, the products made and asked for on the building sites have been of such sizes that this limitation of the rising height has not created any limitation of the production. But there seems to be a tendency towards asking for ever larger building units.

The limitation of rising height thus possibly means that in the future some great sizes will be impossible to procure by the present procedures if an homogeneous quality is to be maintained.

According to the present invention there is provided a method for casting lightweight concrete, characterised in that such a quantity of lightweight concrete mass is first cast into a mould of predetermined size that after being made porous the mass has an almost even porosity, the mass then being permitted to set for so long a time as to withstand a subsequent casting of an additional layer on top of it, and as a second step, such a new quantity of lightweight concrete mass is cast on the previously cast and set one, that it is made [Price 4s. 6d.] 951,035 No. 34844/62 substantially evenly porous and is left to set, this procedure being repeated until the desired height of the cast lightweight concrete is reached.

Before undertaking this subsequent casting it is, however, advisable to water the surface layer of the cast mass. Otherwise there is the 5G risk that this surface layer, which is relatively dry, will absorb water from the mass cast on top of it thus disturbing the setting of the last mass cast and causing the appearance of an unhomogeneous product. Sometimes it has 55 proved advisable to make the surface of the cast layer rough before watering it.

It is possible to avoid the watering of the surface layer of the cast mass by adding water in excess to the mass to be cast. The water 60 quantity should then be adapted to the waterabsorbing ability of the cast layer.

Through the method of the present invention, consequently, when producing such lightweight concrete as is made porous after 65 casting, it is possible to obtain any sizes of the products without a deterioration of the quality. On the contrary it has been observed that the units cast in steps have got a better distribution of their strength than those cast 71.

in one step. This means that they obtain about the same strength at the top as at the bottom, which advantage is not obtained by the one-step units.

The method of the invention is advan- 7 f tageous not only when making unreinforced products but possibly even more so for the reinforced products.

As is well known the reinforced products are made by fixation of reinforcing irons or 8, units into the casting moulds, after which the mass is cast around them, made porous and left to set. The subsequent dividing of the cast mass blocks is done in such a way as to give each building unit at least one reinforcing unit.

951,035 During the forming of the pores in the mass, i.e. when it rises within the mould and envelopes the reinforcing irons, the pores nearest to the irons coalesce and cavities are formed. This phenomenon is generally termed "shadow formation". Its cause is not only the breaking asunder of the mass during rising but also its increasing viscosity which makes it impossible for the mass totally to surround the irons when rising around them. This means in practice that the farther the reinforcing irons are situated from the bottom of the mould the greater the shadow formation becomes.

As the shadow formation causes a deterioration of the quality of the units and must be counterbalanced in some way, for example through an oversizing of the reinforcements the producers have always tried to eliminate the shadow formation. Attempts have been w4ade to use oval reinforcing:irons in order thereby to-weaken the resistance that occurs when the mass is rising around the irons.

But, so far no satisfactory results have.been gained.from- these experiments.

Using the casting method described above, it has. proved possible to eliminate. the shadQw fojmation totally or partly, as desired.

The thickness.of-:the layers will then have:to be adapted to the. size of the irons, their orientation with respeot to the rising- direction, the viscosity of the mass, the. rapidity of-therising and the setting.