AU8841898A - Apparatus and method for the manufacture of lightweight concrete blocks - Google Patents

Description

Regulation 3,.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFI.CATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant~ Actual wnecafor.

Address for service in Australia: LAWNSON EXCAVATIONS PTY LTD Robert La--vson CARTER SMITH BEADLE 2 Railway Parade Cambenvell Victoria 3124 ASustralia -APP-ARAkTUS 'METHOD FOR TIHE MLANUFACTURE OF LIGHTWETIGHT CONCRETE BLOCKS Invention Title: Details of.Associated ProvisionaleAplicaion:- P0 9740 filed 10 October 1997 he f'orov, ing smene is a H1l descriptio of this invatim n cluding th.e begt n-ethd of pcfo =9n it kna~m to us APPARATUS METHOD FOR THE MANUFACTURE

OF

LIGHTWEIGHT CONCRETE

BLOCKS

Field of the Invention This invention relaes to an apparatus and method for the manufacture of lightweight concrete or similar moulded constructional material blocks.

Backaround of the Invention Foamed lightweight concrete or similar moulded constructional material blocks have been used in the construction industry for many years, but the use of such blocks has not achieved wide acceptance due to costs and inconsistencies associated with the manufacturing process. One commercially available product is known as Lite Crete, and the company which manufactures this product also markets a chemical foaming agent for use in the manufacture of lightweight concrete.

Advantages of lightweight concrete or similar moulded constructional material products include significantly reduced weight, reduced costs, reduced construction costs and the ability of the product to be shaped without the use of specialised tools.

Lightweight concrete blocks are currently made by casting large slabs of -lghtweight concrete and cutting the slabs into blocks before the concrete has completely cured. This is a labor intensive process which increases the cost of each block significantly.

Summary of the Invention and Object It is an object of the present invention to provide an apparatus and method for forming lightweight concrete or similar moulded constructional material blocks which reduces the cost of manufacture of such blocks.

In one form, the invention provides an apparatus for moulding lightweight concrete blocks, comprising one or more moulds each having sides, ends and a base defining the desired block form, the base being separate from the sides and the ends, means for pushing a moulded block from the mould using the base while the lii ltweight concrete is still green, and means for curing the moulded block after removal from the mould.

TRS A 9 stICA 1991 In one preferred form, the base(s) comprise a plate having external dimensions slightly smaller than the internal dimensions of the sides and ends of the mould, seal means provided on the lower face of the base and adapted to co-operate with supporting lips extending inwardly from the sides and ends to sealingly support the base during the moulding process.

The base may be formed with an upstanding mould member which forms a "frog" on the lower face of the block.

The means for pushing the moulded block from the mould can comprise a ram member which engages the base and pushes it vertically to eject the moulded block from the mould whereupon the moulded block is removed to a curing oven or the like where the block(s) are completely cured.

The ram means is preferably carried by a frame for supporting an array of S. moulds, along which frame the array may be advanced to sequentially remove the moulded blocks from each mould.

In another aspect, the invention provides a method of forming constructional blocks comprising the steps of pouring a free flowing constructional material into a mould, allowing the constructional material to partially cure, pushing the partially -o cured block from the mould, and fully curing the block.

The method is preferably conducted using the apparatus defined above with ;i 20 the partially cured block being pushed from the mould by means of a separate base i plate which co-operates with the sides and ends of the mould to complete the mould Sstructure.

In a preferred form of the invention, the material is allowed to cure to a green state for a period of approximately 18 to 24 hours, following which the green blocks are filly cured by means of a steam heating process. The steam heating process is preferably controlled to increase the temperature of the block over a period of time to ensure that the block does not crack, the curing temperature being held for another period of time, following which the temperature is gradually lowered, again in a manner which prevents cracking of the blocks. In a particularly preferred form, the blocks are heated to their curing temperature of about 60"C over a period of SOc-to 9.t -4about two hours, the blocks being held at curing temperature of about 60 C for about two hours and then gradually lowered in temperature over a period of about two hours.

The lightweight concrete mixture is preferably prepared in accordance with instructions supplied by the manufacture of the foaming agent, such as Lite Crete.

In this way, the moulded mixture is substantially uniformly aerated to produce a product having substantially consistent strength.

Brief Descriotion of the Drawines In order that the invention may be more readily understood, one presently preferred embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view from above of two of the moulds embodying S"the invention; .Figure 2 is a perspective view from above of the mould with the base plate 15 removed; Figure 3 is a perspective view from above of the mould base plate; Figure 4 is a perspective view from end of an apparatus for ejecting moulded products from the mould, and Figure 5 is a sectional end elevation of the mould and the ejecting apparatus.

20 Description of Preferred Embodiment "Referring firstly to Figures 1 to 3 and 5 of the drawings, each mould comprises sides 1 and 2. ends 3 and 4 and a moveable base plate 5, which in the present embodiment incorporates an upstanding mould element 6 shaped to form a suitable "frog" in the bottom of the moulded block. It will be noted from Figures 1 and 2 that an array of moulds is formed into a single unit divided into individual moulds.

Referring particularly to Figures 3 and 5 of the drawings, the base plate includes rubber sealing strips I which engage inwardly directed lips 7, 8, 9 and extending from the sides 1 and 2 and ends 3 and 4 of the mould as shown in Figure 2. The base plate 5 is inserted into the mould and seals against the lips 7 to 10 so T\3 C4- _I 006 lWj that it can be filled with foamed lightweight concrete mixture without signiticant leaking.

When the moulds have been filled, and the lightweight concrete cured to a green state over a period of about 1S to 24 hours, the moulds are advanced along rails 12 and 13 of a supporting apparatus shown in Figure 4 of the drawings until each mould is aligned with the ejecting ram 14, arranged so that its pusher plate engages the base plate 5 of the mould to push the partially .ured lightweight concrete block from the mould. if necessary, means (not shown) are provided to hold the moulds on the rails 12. 13 as the blocks are ejected from the moulds.

Following removal of the green blocks from the moulds, the blocks are placed in a steam heated curing oven (not shown) where the temperature is increased to the .:curing temperature of about 60'C over a period of about two hours, held at that temperature for about two hours and the temperature reduced gradually over a period of about two hours. This method of curing reduces the likelihood that the blocks will crack as they are cured and produces a block having uniform strength characteristics.

As mentioned above, the foamed concrete material can be prepared in accordance with the instructions provided by the manufacturers of the foaming agent, but the components of the concrete mixture and the amount of foaming agent used S. 20 must be carefully controlled to ensure the required uniformity of aeration in the final product. In particular, the apparatus which mixes the concrete mixture and the foaming agent must be carefully controlled to ensure uniform mixing and resultant foam production within the concrete mixture.

CA C~ V\

Claims (12)

1. An apparatus for moulding lightweight concrete blocks, comprising one or more moulds each having sides, ends and a base defining the desired block form, the base being separate from the sides and the ends, means for pushing a moulded block from the mould using the base while the lightweight concrete is still green, and means for curing the moulded block after removal from the mould.

2. The apparatus of claim 1 wherein the base(s) comprise a plate having external dimensions slightly smaller than the internal dimensions of the sides and ends of the mould, seal means provided on the lower face of the base and adapted to co-operate with supporting lips extending inwardly from the sides and ends to sealingly support the base during the moulding process.

3. The apparatus of claim 1 or 2, wherein the base is formed with an upstanding mould member which forms a "frog" on the lower face of the moulded block.

4. The apparatus ofclaim 1, 2 or 3 wherein the means for pushing the moulded block from the mould comprises a ram member which engages the base and pushes it vertically to eject the moulded block from the mould whereupon the moulded block is removed to a curing oven or the like where the block(s) are completely cured.

The apparatus of claim 4, wherein the ram means is carried by a frame for supporting an array of moulds, along which frame the array may be advanced to sequentially remove the moulded blocks from each mould.

6. An apparatus for moulding lightweight concrete blocks, substantially as hereinbefore described with reference to the accompanying drawings.

7. A method of forming constructional blocks comprising the steps of pouring L a free flowing constructional material into a mould, allowing the constructional material to partially cure, pushing the partially cured block from the mould, and filly curing the block-

8. The method claim 7, wherein the method is conducted using the apparatus defined in any one of claims 1 to 6 with the partially cured block being pushed from 9Ocxcbt i9 the mould by means of a separate base plate which cooperates with the sides and ends of the moulds to complete the mould structure.

9. The method of claim 7 or S. wherein the constructional material is allowed to cure to a green state for approximately IS to 24 hours, following which the green blocks are fully cured by means of a heating process. The method of claim 9 wherein the heating process is controlled to increase the temperature of the block over a period of time to ensure that the block does not crack, the curing temperature being held for another period of time. following which the temperature is gradually lowered, again in a manner which prevents cracking of the block.

I

11. The method of claim 10. wherein the blocks are heated to their curing temperature at about 60'C over a period of about 2 hours, the blocks being held at the curing temperature of about 60'C for about 2 hours, and then gradually lowered in temperature over a period of about 2 hours.

12. The method of any one of claims 7 to 11, wherein the free flowing constructional material is a lightweight concrete mixture prepared in accordance with the instructions supplied by the manufacturer of the foaming agent, such as Light Crete, to ensure that the mixture is substantially uniformly aerated to produce a product having substantially consistent strength. S13. The method of any one of claims 7 to 12. substantially as hereinbefore described. DATED: 9 October 1998 CARTER SMITH BEADLE Patent Attorneys for the Applicant: LAWSON EXCAVATIONS PTY LTD