WO1996026819A1

WO1996026819A1 - Procedure for making a pallet for grouting concrete products using blockmaking machinery

Info

Publication number: WO1996026819A1
Application number: PCT/DK1995/000090
Authority: WO
Inventors: Niels Jørgen JACOBSEN
Original assignee: Jacobsen Niels Joergen
Priority date: 1995-02-27
Filing date: 1995-02-27
Publication date: 1996-09-06
Also published as: DE19581927C2; AU1807195A; DE19581927T1; AU715141B2; DK97797A

Abstract

Using plywood pallets from quick-growing species, mainly birch or tropical hardwood, or pallets from extruded thermoplastic profiles, is familiar method. The present invention relates to using pallets made from a polymer concrete compound as underlay for grouting concrete products on blockmaking machinery. Polymer concrete pallets (20) form part of the concrete grouting process in the following way: from a stockpile the pallet is placed in the feeder of the blockmaking-machine (10). A feeding device takes the pallet to a conveyor roller (14), from where the pallet is fed into the blockmaking machine. The mould (11) is charged, using the pallet as underlay, and is pressurized and vibrated (12, 13) for less than 10 secs. From here the conveyor roller takes the wet concrete products to a stacker, and then on a truck to a drying (curing) plant. After drying overnight the concrete products are de-moulded, and the pallets are taken back to the pallet stockpile.

Description

Procedure for making a pallet for grouting concrete products using blockmaking machinery

Description

This invention relates to the procedure of producing a pallet to be used as an underlay when manufacturing concrete products on blockmaking machinery with a particle size of up to 1/3 of the wall thickness machinery, such as foundation bricks, flags, paving blocks, and kerbs. The pallet is shaped as a rectangular slab, e.g. with the following dimensions: thickness 24 mm, length 1100 mm, width 650 mm.

Current technology uses wood or thermoplastics used for making pallets, for instance the German patent DE 40 905 A 1. Two types use wood, either as plywood with a coating film of phenolic resin, or as boards held together by traverse pins and two C-shaped end profiles.

Besides mould release agent, the process exposes the pallet to hard wear, caused by vibrations combined with pressure, moisure, heat, and static load. The combined effect of pressure, vibrations, alkaline leaching, varying temperature and moisture causes the thin coating to deteriorate quickly, and subsequently the wood becomes soft and spongy. The wood has now lost its capacity for transferring compression to the concrete product. This in turn produces a lower product density, that is, an open-textured product with reduced mechanical strenght and increased water-absorption capacity. Eventually this may cause product deterioration by frost erosion.

In thermoplastic pallets exposed to the aforementioned conditions, swelling is caused by fluctuating humidity and surface degradation which make the pallet surface soft and spongy, thus leading to the problems already mentioned.

This invention applies a mixture of hydrophobic materials to prevent cavities, so as to achieve a water absorption capacity close to zero. By using this procedure the inventor obtains a product that remains unaffected by process technology and environment during its entire lifetime. Furthermore, 50% percent of its volume consists of inexpensive raw-materials, available in nature in large quantities. This is obtained using the procedure, according to the invention, which is unique as stated in the specifying section of Claim 1. According to the invention, the procedure applies a reaction resin combined with a crystalline aggregate, and fibre-glass reinforcements, and the resin polymerises immediately upon mixing and moulding. The crystalline component is selected according to the grade providing a minimal surface area : cubic content ratio.

Max. grade is approx. 1/3 of the wall-thickness. Using the procedure according to the invention, two different methods are applied to enhance the mechanical properties: either by adding fibre-glass reinforcements, be they chopped or continuous strand, woven, knitted, pressed or adhesive (to improve wear resistance), or by adding hollow fillers (tubular or globular) which may be filled with biomass, plastic, foam plastic, glass or fibrous material.

According to the invention the procedure increases product life and enhances the mechanical properties of the pallet, by providing the surface and/or the neutral zone with (a) reinforcement(s) made of chopped strand or continuous strand fibre-glass sheet. In a particular embodiment the pallet is provided with a C-shaped metal profile, with the purpose of enhancing the mechanical properties with regard to the influences arising from deflection as well as from mechanical handling.

All embodiments of the pallet feature recesses for the positioning of piling feet.

The invention is accounted for with reference to drawings, in which Figure 1 shows different embodiments of the pallet; Figure 2 shows the same, however in connection with blockmaking machinery. Figure 1 shows crystalline aggregate or fibre reinforcements (20a); Fibre reinforcements in marginal and neutral zone (20b); C-profile and piling feet

(20c); and globular or tubular openings (20d).

Figure 2 shows pallet (20) according to invention, in a blockmaking machine with a feeding mechanism (14 and 15). In the moulder (10) the concrete is poured into the mould (11), the concrete is compressed by vibration (12) and (13), and the product is left to cure as required.

Specimen embodiments of the pallet: - 15 percent by weight: reaction resin

- 84 percent by weight: silica

- 1 percent by weight: fibre-glass reinforcements

- 30 percent by volume: with fillers, hollow or filled grouted in mould, etc.

Claims

Claims:

1) The procedure of manufacturing a pallet, used when grouting concrete characterized by the fact that the pallet is composed of polymer concrete from aggregate and reinforcements bonded by polyaddition, polymerisation or polycondensation of one or more reaction resins in closed moulds with or without overpressure or vacuum, or in open moulds, and that the resin : aggregate ratio is less than 50 percent by volume.

2) The procedure of manufacturing a pallet according to Claim 1 characterized by the fact that the aggregate component is silica, fly ash and/or calcium carbonate with, each with a max. particle size of 1/3 of the wall thickness.

3) The procedure of manufacturing a pallet according to Claim 1 characterized by the fact that the fibre reinforcements may be filled with fibre materials, be they chopped or continuous strand, from glass, wood, textile, and plastic.

4) The procudre of manufacturing a pallet according to Claim 1 characterized by the fact that the pallet is reinforced with tubular or globular hollows, placed randomly or forming a pattern.

5) The procedure of manufacturing a pallet according to Claim 4 characterized by the fact that the hollows are left open or filled with biomass, glass, wood or plastic, which is foamed, woven, pressed, bonded, knittet or crocheted.

6) The procedure of manufacturing a pallet according to Claim 1 characterized by the fact that the surface layer and the neutral zone are provided with chopped or continuous fibre-glass reinforcements. 7) The procedure of manufacturing a pallet according to Claim 1 characterized by the fact that the pallet is reinforced with a metal profile.

8) The procedure of manufacturing a pallet according to Claim 7 characterized by the fact that the metal profile is C-shaped.

9) The procedure of manufacturing a pallet according to Claim 1 characterized by the fact that underside and upper side have recesses for piling feet.