[0001] Road Mat

FIELD

[0002] There is described a road mat used to permit vehicular travel over environmentally sensitive areas, such as muskeg, permafrost or soft ground or other areas which would otherwise be damaged by vehicular travel, such as agricultural land.

BACKGROUND

[0003] There are four types of road mats that are currently being used. A first and most commonly used form of road "mat" made by bolting together three las ers of 2 inch X 8 inch oak or fir lumber to form a mat that is approximately 6 inches thick. This first mat contains between one hundred and two hundred vertically aligned 6 inch bolts. A second road "mat" is made by bolting together sixteen 6 inches X 6 inches X 14 foot pine timbers. This second mat uses horizontally aligned four 8 foot long steel bolts. A third road "mat" places the wood timbers within a steel frame. A fourth, and least common form of road "mat" is made by extruding various "plastics" to form a mat.

[0004] Typically all of these types of mats are 8 feet wide and 14 feet long and the}' may or ma}' not be somewhat interlocking. All of these mats are most commonly used in the same way - the}' are laid end to end and two mats wide on the surface of the ground after minimal disturbance (clearing and/or levelling). The}' are occasional!}' laid in side by side relation, instead of end to end. [0005] When road access is no longer require, the mats are removed because of the metals, plastics or other environmental!}' objectionable components. Most of these mats are intended to be used several times. Removal can cause more environmental damage than placing the mats, because the road mats tend to "sink" into the soft soil. The}' ma}- also become frozen in, thus requiring considerable force to extract them. What is required is a road mat for which environmental damage during removal is not an issue.

SUMMARY

[0006] There is provided a road mat having a bod}' formed entire!}' of multiple las ers of thin wood fibre compressed and bonded together by resins.

[0007] This road mat provides a number of advantages, as will hereinafter be further described. The road mat can be ground up and scattered on site. In some situations, the road mat can be left in place to decompose naturalh' at the end of its use, thereby eliminating the environmental disturbance associated with removal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in an ' way limiting, wherein:

[0009] FIG. 1 is a perspective view of a road mat made of cross-oriented las ers of thin wood fibre compressed and bonded together by resins.

[0010] FIG. 2 is a side elevation view of the road mat illustrated in FIG. 1.

[0011] FIG. 3 is an exploded perspective view of the road mat illustrated in FIG. 1, made by using resin to glue together multiple las ers of wood fibre.

[0012] FIG. 4 is an exploded perspective view of the road mat illustrated in FIG. 1, made by using resin to glue together multiple las ers of sheeting formed by the process illustrated in FIG. 3.

DETAILED DESCRIPTION

[0013] A road mat generally identified by reference numeral 10, will now be described with reference to FIG. 1 through FIG. 4. Structure and Relationship of Parts:

[0014] Referring to FIG. 1, road mat 10 has a bod}' 12 which is preferably the size of all standard road mats which is six inches thick, eight feet wide and fourteen feet long. However, it will be appreciated that road mat 10 will remain functional in smaller sizes as long as body 12 is at least three inches thick, at least four feet wide and at least twelve feet long. It is preferred that road mat 10 be at least three inches thick in order to provide sufficient strength to support a motor vehicle. It is preferred that road mat 10 be at least four feet wide, so two road mats placed side by side can readily handle the wheel base of a motor vehicle. It is preferred that road mat 10 be at least twelve feet long, so as to accommodate the distance between a front axle and a rear axle on a motor vehicle. It will be understood that road mat 10 ma ' also be made thicker, wider or longer than a standard road mat. For example, a road mat which was seven inches thick, twelve feet wide and twenty feet long would still be viable. An upper size limit is dictated by shipping, handling and manufacturing considerations. Referring to FIG. 2, optionally road mat 10 ma ' have a textured upper travel surface 16. One way of texturing upper travel surface 16 is to embed sand 18, gravel 20 or both in with wood fibre 14 in upper travel surface 16. There are alternative ways of texturing upper travel surface 16, such as through the use of a series of corrugations.

[0015] Referring to FIG. 3, in this example road mat 10 is formed entirely of multiple layers of thin wood fibre 14. The cross-oriented las ers preferably include axial las ers 22 which are oriented parallel to longitudinal axis 21 of road mat 10 and transverse layers 24 which are oriented transverse to longitudinal axis 21 . It will be appreciated that there are other las er orientations which could be utilized. Axial layers 22 and transverse layers 24 are compressed and bonded together by resins 26. Wood fibre 14 can take various forms, such as elongated strips or shorter wafers. [0016] Referring to FIG. 2, in this example bod}' 12 has a first engagement 28 at a first end 30 and a second engagement 32 at a second end 34. First engagement 28 is capable of engaging with a second engagement 32 on a bod}' of a like road mat.

[0017] In broad terms, the process of making road mat 10 is the same process used for making oriented strand board and other strand based products. As this process is well known, it will not be further described. However, strand based products do not come in thicknesses that approach three to seven inches. Current strand based product fabrication uses heat to cure the resin. This involves the use of heat plates, often using steam injection. The thickness of strand based products is limited by the ability to apply heat to cure the resin. At best, heat plate technology is only effective within a range of two inches. There are two alternative approaches that are currently being considered to achieve the greater thicknesses. One approach is to continue the deposit of wood fibre 14 until the required thickness is attained, but use alternative means for curing the resin, such as microwaves or a radio frequency technology. Referring to FIG. 4, another approach is to form the thickest strand based products possible, bodies 12a, 12b, 12c and 12d, with existing heat plate technology and then use resin 26 to bond multiple oriented strand based products, bodies 12a, 12b, 12c and 12d, together to achieve the required thicloiess in a cold pressing process that will not adversely affect the integrity of the stand based products, bodies 12a, 12b, 12c and 12d. It is important to note, that no metal fasteners are used in fabrication of the road mats. It is also preferred that a resin 26 be selected that is viewed as being "environmentally friendly". Advantages:

[0018] There are a number of advantages that road mats 10 provide:

1. Wooden mats are sometimes inconsistent in quality, depending upon the quality of the wood that is available at time of manufacture. It is increasingly difficult to obtain good quality wood at a reasonable price or at all. Road mats 10 will be of uniform quality. Furthermore, the}' can be tailored to meet the specific needs of the user regarding durability, strength, and other characteristics such as surface characteristics. Surface characteristics can be important to avoid slippage or surface damage. In order to avoid slippage the surface can be corrugated or sand can be embedded in the surface. In order to reduce surface damage by tracked vehicles, gravel can be embedded in the surface.

2. As Road mats 10 are made entirely of wood fibres and resins with no metals, plastics or other materials, the}' can be left in place to decompose naturally at the end of their use, thereby eliminating the environmental disturbance associated with removal.

3. The resins can be made to suit the durability requirements of the particular application. As a result the road mat can be engineered to disintegrate and start to decompose according to a schedule timed to coincide with the end of its projected use.

4. Road mats are used to protect the permafrost in the far north. In permafrost situations, losing the frost has very significant environmental implications. 3

Removing the road mats when a project is over leaves the soil underneath exposed to sunlight and hastens thawing. As road mats 10 are left in place, the}' will act as an insulator, and protect the permafrost.

3. There are some areas that are only accessible in winter, when soft and otherwise impassable ground becomes frozen. In such areas winter "roads' ^" of ice and snow are created. When road mats are used, they tend to "insulate" the ground surface, so that the hauling season can often be extended by several weeks. This has huge economic implications.

6. There is an ability to customize the thicloiess and strength of the road mat to suit different applications.

Field Testing:

[0019] Thirty mats as described in the above disclosure underwent field testing. The mats had varied thicknesses of either four inches, five inches or seven inches and were created as four foot by eight foot mats. Three mats of the same thicloiess were fastened together to create eight foot by twelve foot mats.

[0020] There is not currently an - commercially available equipment capable of making a road mat of the thicloiess required through the standard process of compressing loose wood fibre using a resin. For that reason the road mats for testing were prepared by purchasing commercially available stand based sheeting and using resins to from multiple las ers of the desired thicloiess through a cold bonding and pressure treating process.

[0021] It was expected that the five inch thicloiess would be adequate and provide a mat with sufficient resistance to wear. It was also expected that the four inch thick mats would fail as the}' would be too easily worn. The four inch thick mats held up well under use and it is now believed that a smaller thicloiess, such as three inches, is sufficient to provide adequate wear resistance. [0022] It was expected that there would be significant damage to the road mats by tracked vehicles which could pull chunks from the mat. It was believed that a restriction to tracked vehicle traffic would be required. It was discovered that the mats withstood the tracked vehicles damaging effects. Indentations were seen in the mats, however there appears to be some resilience of the mats as these indentations were recovered to a degree. [0023] It was expected that there would be slippage concerns when using the mats but it was discovered that this does not appear to be a factor. It would appear that man}- of the surfacing options to increase traction will not be necessary. That being said, to date there has been no heavy winter use and so the effects of snow and freezing temperatures have not been studied.

[0024] It was also expected that the mats would be too fragile to move and would, therefore, be useful for only a single use. It was discovered that the mats are very robust and can be used multiple times. In addition, the mats ma ' be pressure washed to eliminate contamination between work stations. Contamination is also less of an issue as there are no cavities in which mud and weed seeds ma ' become lodged. The mats ma}- be moved using a fork lift and only minimal damage in the form of chipping to the edges was seen when handling the mats with a forklift.

[0025] In the event that the mats are not to be reused the}' ma}' be run through a chipper and distributed or left on site to decompose naturally. It was originally believed that the road mats would be sufficiently deteriorated through use, that rapid deterioration would occur on site. However, the road mats are holding up better than expected and for that reaons the preferred option is now grinding the road mats up and scattering the wood chips to accelerate decomposition.

[0026] The mats were driven over in all directions; length wise and width- ise. There appears to be no difference in the performance of the mat regardless of the direction of traffic. It has been believed that there would be a difference in wear depending upon the orientation. [0027] In all areas of strength, durability and the ability to use multiple times and move from location to location, the mats performed beyond expectations. Additional testing still needs to be done to determine how the mats perform in wet conditions. If excessive swelling of the mats were to occur due to wet conditions, then increased resin content could be used to maintain mat integrity.

[0028] In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items not specificalh' mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearh' requires that there be one and only one of the elements.

[0029] The following claims are to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention ma}' be practiced other than as specificalh' illustrated and described.