GB2030618A - Soil Stabilisation - Google Patents

Abstract

Low moisture content soil, sand, dirt etc., is stabilised in situ by injecting a two pack polyurethane system to produce a load bearing building material. Moisture may be removed from the soil etc. by heating. The invention thus makes possible through use of the existing site materials, the construction of continuous load-bearing slabs, underground drains, pipes, ducts etc. <IMAGE>

Description

SPECIFICATION Improvements In or Relating to DirtlSoil/Sand Stabilization Much prior art exists in relation to dirttsoil/sand stabilization, all of which predominantly involve the use of water, powder chemicals, andtor cements, with no built in capability, with the possible exception of aerated concrete, of expansion after the initial mix. Only limited types of soil are suitable for this purpose and even they have to be exhaustively tested before use. Sand containing only a small proportion of dirt or soil is quite unsuitable for mixing with cement and in all cases setting and hardening times are relatively slow compared with the following innovation.

This invention enables practically all type of dirt, soil, sand or mixtures of same to be stabilised without the use of water, powdered chemicals or cements and by adjustment of the ingredients various degrees of initial expansion, aeration and hardness can be achieved, e.g. the original volume of dirttsoil/sand will increase three to six times and be hard enough for use in minutes The unique material resulting from this invention is achieved by intimately mixing, preferably by whisking or spraying, ordinary dirt, soil and sand with one of the established polyurethane two component chemical systems (or similar).I have discovered that, provided there is very little or no water present in the dirt/soil/sand, the latter can readily be mixed with the chemicals without impairment of even, natural foaming and dispersal throughout the mix, each grain being coated so that the resultant product achieves water repellent, high insulation and tensile characteristics still capable of being sawn, nailed, screwed and sanded. The presence of water in the original dirt/soil/sand produces poor almost negative results.

In order to determine the proportion of chemical required, a given volume of dirt/soil/sand is heated in order to drive off excess moisture, passed through a sieve and whisksaturated with one of the two chemicals, a process which causes no reaction at this state.

The proportions will vary from three to six parts of D/S/S to one of chemical. The second chemical is then added and the whole mixture whisked again.

Foaming starts quickly and the whole mixture rises evenly, expanding its volume by up to six times and setting within minutes.

For commercial use I envisage large whisking machines, on site, close to moulds or shuttering, using site material to manufacture walls, floors, roofs, pre-cast or in situ. These would automatically contain the desired elements of insulation water impermiability, fire-resistance and self-finish.

Given a suitably designed machine which, from the front, would suck up, through sieves, via warm air, a proportion of loose dirt, soil or sand of one inch average thickness and sprayed simultaneously at the rear with the other two chemical ingredients, then such a machine would convert any loose material over which it passed into a four inch deep (approx.) slab, which, if required, could be reinforced with steel (as per concrete), because the D/S/S slab would be more waterproof than concrete. The action of sucking up the fine material automatically leaves a rough, clean surface to which the foamed slab will adhere.

Thustennis courts, hard standings, parking lots etc. would be created out of the ground itself without importation of any materials other than the chemicals which in their raw state are approx.

One twentieth of the volume of the finished slab.

The whole operation is achieved in a fraction of the time required by any other soii stabilisation method and is ideal for the levelling out of potholes in roads, and runways thus avoiding interruption in traffic, and the material can be used instead of sprayed cement on defatable balloons to produce instant, highly insulated, waterproof shelters in areas which have been subject to natural disasters.

!n desert areas the sand would be quickly converted into a substantial base for subsequent road construction and with further experimentation it is possibie that the former could be the road surface itself.

In the creation of D/S/S stabilization over sandy, desert areas it is essential to confine the sand under the slab so that sand can not be blown from under the edges of the slab by wind erosion.

This being achieved as foílows:Fig. 1 b Fig. 2.

The laying machine's horizontal spraying arm (a) is equipped at its extremities with two vertical (or angled) probes (c) which penetrate the subsand or sub-soil to the depth required and as the machine drags them forward liquid D/S/S is forced out under pressure through numerous outlets in the back of the probes.

The D/S/S partly combines with surrounding sand, foams, expands and sets within seconds thus creating a continuous, vertical or angled skirt (b) some four to six inches thick contiguous with the D/S/S slab.

The same principle can be applied to the construction of insitu underground pipes, ducts etc, laid separately or at the time as the siab and skirt, literally extruded under ground via a tool which I shall call the mole. Fig. 3Fig. 4.

In order to achieve the above the probe and the mole must be designed to suit the chemical action of the materials used, Urethane, Phenolic, Styreene etc. The probe and the mole have to be sharp edged or pointed to cut through the sand/soil and the spray holes (d) are protected by an outer sleeve (e) so that an air pocket (f) is created between (e) and the inner mole sleeve (9).

The length of (g} being determined by the speed at which the laying machine is travelling and the time it takes for the D/S/S to set at point (h)* The inner sleeve is preferably tapered to ease withdrawal. Supply pipes (m) in a sharp edged housing (n) connect to a suitable mixing machine.

Thus as the probe or mole moves forward the liquid D/S/S starts to foam and expand into the surrounding sand/soil at about point (j) and is sufficiently set at point (h) to withstand pressure from outside. Under pressure D/S/S developes a tough skin SQ a clean even surface is automatically imparted to the interior of the pipe or duct (k).

Although the cost of the raw chemicals is far greater than the cement in an equivalent volume of concrete, I have proved that the resultant product because of the vast expansion of the original dirt/soil/sand and lighter shuttering is a cheaper construction material.

Chicken-wire, expanded metal, fibreglass strands, coconut fibre, animal hair etc may be incorporated in the D/S/S mix when additionai tensile strength is required in relatively thin sheets, slabs and slim sections.

Claims (10)

Claims

1. A method and apparatus which converts dry dirt, dust, soil, sand, powdered and granulated mateslals ancl mixtures of same (hereinafter called the filler) into a greatly expanded, stabilised, load- bearing product for use in the production and repair of roads, hardstandings etc., walls, floors and roofs, pipes and drains etc.

2. A method and apparatus in accordance with claim 1 whereby the mix, for optimum expansion and cornpressive strength is six parts of filler to one of each part of a commercialty available two pack polyurethane system.

3. A method and apparatus ín accordance with claims 1 Et 2 whereby fibreglass strands, coconut fibre, animal hair etc., may be incorporated in the filler.

4. A method and apparatus in accordance with claims 1 to 3 whereby the loose material liying in pot-holes can be used as filler to level off the hole.

5. A method and apparatus in accordance with claims 1 to 4 whereby water and moisture is dried off from the filler before mixing.

6. A method and apparatus in accordance with claims 1 to 5 which eliminates the conventional use of water, cement, bitumen and resins as binding and foaming agents and eliminates conventional on site in-situ mixing or agitation.

7. A method in accordance with claims 1 to 6 which can make use of commercially available mixing, whisking and spraying machines presently used for other purposes.

8. A method and apparatus in accordance with claims 1 to 6 whereby the construction of continuous, in-situ slabs, underground drains, ducts, skirts etc., can be produced from any filler vying on the surface.

9. Method and apparatus in accordance with claim 8 whereby the filler is sucked and sieved from the surface, dried and ejected simultaniously via separate jets into the jet-streams of the two chemical components as the apparatus moves slowly away.

10. Apparatus in accordance with claim 9 whereby the three jet streams impinge on the exterior surface of a siowly moving mole to form underground pipes, drains, ducts etc.