The present invention relates to an insulating structure which can be used to prevent soil from freezing to an extent such as to cause so-called frost damage, and also for other insulating purposes, e.g. in roof insulations, and which comprises two sections, each including a plurality of mutually adjacent insulating slabs or sheets.

It is well known that in order for soil to freeze such as to cause damage to objects in the proximity thereof, it is necessary for water to be present in the soil and for the soil to be subjected to frost. It is also known that such frost damage can be prevented or avoided, by preventing frost from penetrating to water-containing regions of the soil by draining such regions and/or by preventing the passage of water thereto. Different drainage methods and different methods of replacing impervious mass, e.g. roY down to frost free depths are used to this end. With regard to roads, highways, etc., the road pavement structure includes a sub-base which forms the lowermost layer of the road pavement structure and which normally consists of gravel-like or sand-like material. Due inner alia to its lew capilarity, this layer ^" will prevent the transport of water from the road sub-structure to the upper layer of the pavement structure and will reduce the bearing capacity of the road and increase the risk of frost damage thereto. The thickness of the sub-base varies in dependence on just how prone the road sub-structure is to frost damage, and in unfavourable circumstances may in each case reach, one meter. Although these safety measures make it difficult for water to penetrate to the pavement structure, frost damage nevertheless often occurs, and consequently various methods have been tried to stop or to reduce frost, penetration into the road sub-structure, with the aid of various kinds of

insulating layer. One example of such known frost damage eliminating layers is found disclosed in Swedish Patent Specification 3^2 276.

In recent times ground insulation intended for preventing frost damage to walls, building foundations, courtyards, parking lots and like structures has comprised almost exclu¬ sively of cellular plastic insulating slabs or blocks which are laid out manually, edge to edge and one at a time on a smooth bed of sand. In order to prevent the slabs from sliding apart, pegs or stakes are normally driven into the ground, through the slabs in the outer rows and sand is often heaped on the slabs as they are laid out, in order to prevent the slabs from moving in relation to one another during subsequent working operations. The task of laying out the slabs by hand is both laborious and time consuming, and thus a very expensive method of providing protection against frost damage. Furthermore, it is difficult to achieve and maintain tight abutment between mutually adjacent slabs, even after applying the pavement structure material; instead the slabs as a rule, are moved apart by the pavement material as it ^: is applied, so as to form gaps through which frost can penetrate down into the sub-structure and water can penetrate from underlying ground up into the pavement structure.

Another factor which adds to the cost of this type of insu¬ lation lies in the fact that the cellular plastic used in the insulating slabs must be water ^" repellent, which means that a relatively expensive plastic must be used, e.g. an extruded styrene cellular plastic having a bulk density of O kg/m ³ .

Consequently, an object of this invention is to provide an insulating structure which will function effectively as a protection against frost and which is also .v ^τ ell suited for

other insulating purposes, e.g. as roof insulation. and which can be readily laid out and placed in position without risk¬ ing the occurrence of thermal bridges or water permeable spaces or gaps in the laid insulation. Furthermore, when required or if so desired, it should be possible to use sub¬ stantially cheaper material in the insulating structure than was hitherto possible in the construction of an effective protection against frost.

This object is achieved with the inventive insulating struc¬ ture having the characterizing features set forth in the characterizing clauses of the following claims.

The invention is described in more detail hereinafter with reference to ^.he accompanying drawings, in which Figure 1 is a perspective view of one embodiment of the inventive insu¬ lating structure; Figure 2 is a sectional view in larger scale taken essentially on the line II-II in Figure 1; Figure 3 is a perspective view of a supplementary element which is complementary to the Figure 1 embodiment and which is effective in the construction of a double layer of insu¬ lation; Figure ^' is a sectional view of an insulating struc¬ ture incorporating the supplementary element; Figure 5 is a perspective view of an alternative embodiment of the inven- tive insulating structure; Figure 6 is a perspective view of an upper or lower part of this latter embodiment; Figure 7 is a perspective view of this latter structure part when folded-up and ready to be packaged, transported and laid out; Figure 8 is a perspective view of a folded intermediate part of the embodiment illustrated in Figures 5 and 6;

Figures 9 and 10 illustrate a hinged configuration of a part of the inventive insulating structure and show the part in a flat state and in an angled state respectively; Figure 11 illustrates a hinged configuration of the upper part of the Figure 1 embodiment and shows said upper part when angled; Fiεure 12 is a longitudinal sectional view of a tapering

embodiment of the present invention; Figure 13 illustrates laying of the inventive insulating structure; and Figure 1*. illustrates the use of the hinged embodiment illustrated in Figure 11.

The inventive insulating structure, which can be used to eliminate the risk of soil freezing or for other insulating purposes, includes at least one base section 1 and a top section 2, each of which has a mat-like configuration and can be produced in any desired length. Each such section 1, 2 includes a respective carrier foil 3 and 4 made of water- impermeable plastics material, and a plurality of mutually adjacent insulating slabs 5 and 6, the numbers of which correspond to the lengths of respective carrier foils and which are bonded -to said foils, e.g. as by gluing or stap¬ ling. The foils may cover the slabs 5 and 6, either comple¬ tely or partially, and may also be made wider than the slabs, as illustrated by the chain line 7 in Figure 1.

The interspacing of the slabs 5 in the base section 1 is determined by the widths of the slabs 6 in the top section 2, such that the slabs 6 of the top section will fit into the spaces δ between respective slabs of the base section 1, and vice versa. Thus, when the top section 1 is placed on top of and fitted to the base section 2, there is formed an integratd insulating layer which exhibits no thermal bridges and which is protected against moisture and water penetra¬ tion from both beneath and above the foil coverings 3, 4 of the two sections.

When the insulating slabs of both the top and bottom sec¬ tions 1, 2 are composed of an insulating material which is water repellent in itself, e.g. extruded styrene cellulose plastic having a bulk density from 30- 0 kg/ir- , there can be used in principle, a foil material which is moisture per¬ meable. Neither need the foil cover the insulating slabs

completely, since in this case it suffices for the foil to cover said slabs solely to an extent at which said foil will function as a carrier for the slabs of respective sections and fixate the mutual positions of said slabs, in the inten- ded manner.

The slabs 4, 5 of both the top and base section of the inventive insulating structure have a trapezoidal cross-sec¬ tional shape, which is advantageous for the reason that a wedge effect is achieved between the slabs 4, 5 of said sec¬ tions and therewith a sealing interface abutment there¬ between, and also because the foil in both the top section and the base section will be stretched at the same time as the base section slabs 4 are mutually locked in a manner which is ^' so effective as to enable the slabs to take-up loads exerted both from above and from beneath, e.g. frost heave, without appreciable movement between the slabs. Natu¬ rally, the slabs 5, 6 of respective sections may have cross- sectional shapes other than that illustrated, e.g. a rec- tangular cross-section, although the illustrated cross-sec¬ tion is preferred because of the wedging and locking effect obtained between -the top and base sections 1, 2 when the insulating structure is under load.

The insulating slabs 6 of the top section 1 may have the same width as the plates 5 of the base section 2, in the case shown in Figures 5-7, or may be wider than said slabs 5. As a rule, however, the top section slabs 5 will be narrower than the base section slabs, as in the case of the Figures 1 and 2 embodiment in which the top section slabs have a bar or strip shape and which may even have -a width smaller than twice the slab thickness. VJhen the width of the slab surface remote from the foil, and therewith a spacing between the slabs 5, 6 adjacent the foils 3 and 4 respecti- vely, is at least equal to twice the slab thickness, a highly advantageous construction is obtained which enables

each insulating mat or section 1, 2 to be packaged with res¬ pective slabs 5, 6 in mutual abutment, as illustrated in Figures 7 and 8, and even vacuumed packed in an envelope (not shown) , in a moisture proof fashion when the need arises, whereby the package obtains the smallest possible volume, which is of important benefit with regard to transportation, while enabling the sections, or mats, to be withdrawn readily from their respective packages and laid directly on the intended foundation surface.

In the case of the Figure 5-7 embodiment, the base section 1 and the top section 2 correspond to one another, as is illu¬ strated in Figures 6 and 7 by the inclusion of bracketed reference numerals corresponding to the top section 2.

In accordance with the concepts fundamental to the inven¬ tion, the inventive insulating structure may include at least one interlay or complementary section 9, as illustra¬ ted in Figure 3 and Figure 4, by means of which the insula- ting thickness of the insulating structure can be doubled. Obviously, this thickness can be trippled, etc., by inclu¬ ding a further' interlay 9, or further interlays.

The interlay illustrated in Figure 3 belongs to the embodi- ment illustrated in Figures 1 and 2 and includes a carrier foil 10, which need not necessarily be moisture proof, with one side of the foil joined to insulating slabs 11 which correspond exactly to the slabs 6 of the top section 2, and with the opposite side of the foil joined to insulating slabs 12, which correspond exactly to the slabs of the base section 1, the slabs 11, 12 on both sides of the foil 10 of said interlay 9 being joined mutually with the foil 10 so that the longitudinal centre lines of said slabs mutually coincide or lie in one and the same plane at right angles to said foil 10.

Figure 4 is a sectional view showing an insulating structure according to the Figure 1 and 2 embodiment laid on a founda¬ tion surface and incorporating an interlay 9, with the bar¬ like slabs 11 of said interlay located between the base sec- tion slabs 5 and the insulating slabs 12 of said interlay located between the bar-like insulating slabs 6 of the top section. The aforesaid interlocking effect between the slabs of the various sections is also obtained in this case.

Figure 8 illustrates an interlay for the embodiment of

Figures 5 and 6 in a folded state, in order to show that such interlays can also be packaged with their respective insulating slabs in mutual abutment, when the distance between the slabs is at least equal to twice the slab thickness.

In accordance with the concept of this invention, the base section 1 and the top section 2 can be hinged with their respective foils 3 and 4 serving as hinge means (Figures 9-11), by dividing each individual slab located on a foil 3, 4 into two parts (cutting through said slabs) in one and the same longitudinally extending plane 13, or by arranging two slabs 5 and two slabs 6 in respective edge-to-edge abutment, with the mutually opposing edges of respective slabs being left free from one another and lying in said common plane 13. Such a hinged part 1, 2 can thus be swung through 180° in one direction. A hinged base section 1 can be used, for instance, for insulating both side surfaces of a corner structure, wherewith if the one corner surface is vertical, a top section associated with said base section can be nailed, stapled or glued to the base section part.which covers the vertical surface.

In the case of ground insulation in particular, it is sometimes desired to taper the insulating layer down to zero. An embodiment to this end is illustrated in Figure 12.

In ^' the case of this embodiment, the base section slabs 5 have decreased thickness in a direction towards one end of the insulating structure, as do also the slabs 6 of the top section, wherewith each such slab 6 decreases in thickness in its transverse direction, either continuously or dis- continuously, with a total reduction in thickness corres¬ ponding to the difference in thickness between two mutually adjacent slabs 5 in the base section 1. In the case of the Figure 12 embodiment the decrease in thickness of the slabs 6 in the top section is discontinuous.

Figures 13 and 14 illustrate the orientation of inventive insulating structures in forming a frost protector in a road construction. This frost protector or insulating structure is formed by first placing a plurality of base sections 1 in mutually adjacent relationship, with the plastic layer 3 towards a well smoothed, previously prepared bed 15 of sand or like material. Top sections 2 are then placed on the base sections 1, while ensuring that each top section 2 extends over two mutually adjacent base sections 1, such as to cover the join 16 between two base sections, the edge parts being covered by top' sections 2 of corresponding widths, e.g. half the normal width. In order to avoid the occurrence of an opening between two top sections 2 or between two base sεc- tions 1, the respective foils 4 and 3 of said sections can be caused to extend somewhat beyond the one end edge of the slabs, such as to form flaps 7 (see also Figure 1) which overlap the foils 5 and 6 of respective adjacent sections.

The end surfaces of the slabs can be coated with a water repelling material, so as to prevent the ingress of moisture into said edges.

Subsequent to laying out a sufficient number of top and bottom sections 1 and 2 to cover the area intended, a mate¬ rial filling 17 can be applied to the top of the resultant

Insulating structure formed by surface laid sections 1, 2, whereby the sections 1, 2 are compressed zo form an imper-

vio ^' us, coherent insulating structure, while at the same time the plastic layers 3 _. 4 on the upper and lower surfaces of the insulation prevent water from coming into contact with the insulating slabs 5, 6, both from beneath and from above, and also from penetrating through the insulation to the pavement structure of said road.

Figure 14 illustrates one aspect of use of the hinged embo¬ diment of a top section according to Figure 1, this aspect being particularly suitable in those instances when one half 18 of the road is to be traffic bound and the other half 19 is to be closed while repairs are carried out thereon. In this case, the slabs 6 in the top section 2 are divided cen¬ trally, wherewith the plastic layer 4 functions as a hinge means which enables one.half of the top section 2 to be fol¬ ded up against the edge 20 of the traffic bound road half 18, where it serves as a partition wall between the traffic bound road surface 18 and the filling 21 placed on top of the laid-out insulating structure 1,2 in the road half 19 under repair or construction. When repair to this half of the road has been completed and can again carry traffic, the other road half 18 is dug up and after laying out base sec¬ tions 1, the upstanding part of the top section 2 in Figure 14 is swung down onto the nearest adjacent base section, so as also to obtain therewith effective sealing of the insula¬ ting structure at the junction between the two road halves.

The present invention enables an insulating structure to be constructed very rapidly, without risk of the slabs included in said structure sliding apart, and also enables, when desired, the insulating plates to be protected against moisture both from beneath and from above. In such cases, the slabs may also be comprised of a substantially cheaper plastics material than was hitherto possible for ground insulating purposes.

It will be understood that the present invention is not limited to the aforedescribed and illustrated embodi¬ ments, and that various modifications and changes can be made within the scope of the invention defined in the following claims.

For example, materials other than plastic materials can be used in the layer serving to carry the insulating slabs. When the insulating structure is to be used to insulate roofs, the carrier layer 4 of the top section may comprise tar paper or some other suitable roof covering. In other words, the carrier layers can be adapted to their intended environments and to their particularly intended purposes. In those instances when the top sections, base sections and/or interlays cannot be stacked with respective slabs lying on or adjacent one another, each such section or interlay can be rolled up and packaged in a tubular wrapper, sleeve or the like.

An insulating and sub-base layer with very good and long-term acting insulating ability is obtained with the present invention and could be used as reinforce¬ ment and strengthening of different kinds of construc- tions and structures which need increased stability and bearing capacity. The invention is useful within a number of different fields and as an example of such fields can be mentioned different applications such as for instance roads, railways, planes and parking places, water conduits, wells, road culverts, roofs, foundations, foundation walls and temporary roads on areas with bad bearing capacity and this invention could also be used as ground protection in and for various fields and as reinforcement of slopes and so on.

Every such layer can include two or more insulating parts.that each includes insulating plates and a bearing layer joining these in relation to one another. When joining such insulating parts, a uniform and combined insulating layer is obtained, making it possible to fix the insulating parts of the insulating layer with one another by applying a pavement structure on the insulating layer or by glueing of the insulating parts. By the elasticity of the bearing layer laid, insulating layer could be exposed to movements without any deterioration of the insulating and bearing ability.

Are waterproof bearing layers used, the insulating ability ₍ of cellular plastics, e g of type EPS, could be improved substantially thanks to the protection to water given by such bearing layers.

So-called geotextiles and/or so-called geonets can also be used as bearing layers, preferably when insulating materials with low water absorption are used, e g extruded cellular plastic. Geotextiles used as bearing layers mean an increased stabilization and pressure distribution, resulting in the fact, that the inventive device can be used and carried out in a more cost- reducing way. By using geotextiles, which is an extremely heavy duty and strength material, under¬ grounds do not need to be intermixed with externally supplied superstructure material.

Another advantage with this invention is that all types and all thickness of cellular-plastics-based insulating plates can be used as well as other insulating material, such as for instance cork and mineral wool and the like. With the construction of the insulating parts according to this invention, a very rational handling as to package, transport and laying out is

achieved and furthermore, an extensive standardization as to manufacture of the different part components is made possible.