The invention relates to a mat of a liquid- tight, flexible material for the collection of treat¬ ment fluid when operating on objects pulling in on the mat, in particular for the collection of deicing fluid during the deicing of an aircraft, the mat comprising at least one discharge opening.

The disclosure of WO 79/00331 and US 3,533,395 deals with systems for deicing aircrafts. The perimeter dyke is covered with fluid-impermeable concrete or asphalt. According to WO 79/00331 the deicing fluid is drained off through wells and subsurface pipelines, and according to US patent No. 3,533,395 through a trench along part of the circumference of the perimeter dyke.

Said systemts suffer from the inconvenience that they cannot be moved to another site, and that an occurring leakage in the concrete or asphaltic covering is very troublesome to repair and that they necessitate a long establishing phase requiring the strip to be closed. DE 3,834,357 relates to a mat of the above men¬ tioned type for use in connection with car washing. The mat has upright detachable or inflatable side walls for salvaging the washwater. Upon driving-in and driving- out the side wall is either removed or it is being run over. Such side walls dyking the fluid are unsuitable with respect to mats that are so large that the oper¬ ating crew of men standing on the mat when in use, firstly, because a "puddle" may form on the mat and, secondly, because the free passage is impeded by the side walls. Moreover, a mat of said material has a ten¬ dency to bulge directly downstream of the drive wheels of the craft pulling in on the mat. This bulging impedes the free movement of the wheels and it further

causes strong, local deformations to occur in the mat material, resulting in a fast deterioration thereof.

It is the object of the invention to provide a mat eliminating such bulging from forming and which does not suffer from the above inconveniences.

This is obtained according to the invention with a mat of the above mentioned type that is characterized in that the mat includes means for stiffening the mat in the direction of travel on it. It is thus obtained that the mat is rigid in the direction of travel on it, thereby preventing the men¬ tioned bulging from forming.

A preferred embodiment of the mat is character¬ ized in that the stiffening means are made from metal and that they are embedded in the mat material. The metallic stiffeners may preferably be steel wires.

A mat manufactured in this manner is stiff in the direction of travel but is flexible in the direc¬ tion perpendicular to the direction of travel, and it may be rolled with the view of conveyance from one site to another. In view of the fact that the stiffener means are encompassed by the mat material they are not subjected to any corroding impact from the treatment fluid or from any general decomposition process caused by weather conditions.

An embodiment of the mat is characterized in that it comprises grooves for flowing the treatment fluid to at least one discharge opening. Said grooves extend preferably transversely to the direction of tra- vel . In a further embodiment the grooves discharge into collecting trenches extending along the edges and discharging into at least one discharge opening. In yet an embodiment some of the grooves discharge at the edges of the mat and the outlets of the grooves consti- tute the discharge openings.

Said embodiments provide for flowing the fluid through the grooves to a discharge opening that may be

connected with a collecting well in the subjacent layer or the grooves may be extended to the edges of the mat from which the fluid is drained down into for instance a digged, prefabricated or cast trench extending along the circumference of the mat. Collected fluid may be flown from this trench further on to a plant in which it is for instance pumped up and purified for reuse. It has further turned out that the grooves ensure the fluid on the mat not to be blown away by the jet stream from the aircraft engines.

A further preferred embodiment of the mat according to the invention is characterized in that it is composed of mutually parallel webs extending trans¬ versely to the direction of travel. Along their edges the webs may further be provided with engaging means for engagement with fixtures for affixing, on one hand, the webs to each other and to the subjacent layer on which the mat is placed and, on the other hand, for sealing the joints between the webs. It has thus been made possible to construct very large mats that are necessary e.g. with respect to the deicing of air- crafts.

On its surface the mat may between the grooves have upright friction promoting members between which the treatment fluid may be drained to the grooves. This offers a safe footing on the mat to the vehicles as well as to the staff, even when using greasy treatment fluids.

The invention will now be explained in detail by means of an example with reference to the drawings, in which

Fig. 1 is a sectional view along the stiffeners of a mat, according to the invention, with grooves,

Fig. 2 is a section along the line II-II of the mat in Fig. 1,

Fig. 3 is a sectional view of the mat in Fig. 1, viewed from above,

Fig. 4 is a plane view of a mat consisting of several webs of mat joined together and secured by fixtures,

Fig. 5 is a sectional view along the line V-V in Fig. 4, illustrating on a larger scale two adjacent mat webs assembled and secured by means of a fixture, and

Fig. 6 is a sectional view of a trench along the edge of the mat in Fig. 4.

The mat 1 illustrated in Figs 1 and 2 is made from vulcanized rubber and includes a bottom section 2 with embedded stiffeners in the form of a large number of parallel steelwires 3 twisted together in sets of three wires, and a top section 4 containing rectili¬ near grooves 5 extending perpendicular to the stif- feners and thus to the direction of travel on the mat. Grooves 5 have by and large a plane bottom 6, and the groove sides 7 are sloping a little from each other so that the groove opens a little towards the upper side 8 of the mat. The area of the cross sec- tion 9 of the material between two adjacent grooves 5 is about twice the the cross-sectional area of a single groove. The parts 9 located between the grooves of the top section 4 of the mat are thus capable of sustaining the concentrated load originating from a wheel of a vehicle without exerting any excessive stress on the material edges at the grooves.

Fig. 2 illutrates that the twisted wires are woven with a layer of perpendicularly extending yarns 10 acting in this case as a strengthening or reinfor- cement of the rubber material of the mat. It would, however, also be possible to make use of an independent reinforcement, e.g. consisting of an embedded canvas fabric.

As it appears from Figs 1 to 3 the upper side of the mat is designed with a pattern consisting of a large number of closely spaced, upright bodies 11.

This design ensures that the mat is non-slip, even when using greasy or lubricating treatment fluids, the fluid being capable of flowing between bodies 11 to grooves 5, thereby preventing large coherent fluid surfaces from forming on the mat surface.

Fig. 4 illustrates a mat composed of a large number of parallel webs that are laid out transversely to the travelling direction on the mat. The mat is laid on a taxi strip 12 for an aircraft 13 to be sprayed with deicing fluid. The webs, e.g. 14 and 15, have longitudinal grooves 5 and along the two sides of the mat formed by the ends of the webs a cement-cast col¬ lecting trench 16 is provided which is covered by a grating 17. At one end of each collecting trench 16 there is marked a well 18 from which collected treat¬ ment fluid by means of a pumping assembly, not shown, may be pumped up to a purification plant with a view to reuse. The collecting trenches 16 and wells 18 must be dimensioned so as to be capable of receiving and discharging the actually comparatively large quantities of water that might turn up due to heavy showers.

Fig. 5 illustrates how two adjacent webs of mat 14, 15 may be affixed to each other and to the subja¬ cent layer 12 by means of a fixture 19. Fixture 19 is on its underside provided with protruding sections 20 tightly fitting into corresponding grooves 21 in the surfaces of the mat webs along the longitudinal sides of the webs. Grooves 21 have the same cross- sectional shape as grooves 5 but may alternatively be designed as a dovetailed spline, if desired; the pro¬ truding sections must then have a corresponding shape. Fixture 19 is affixed to the subjacent layer by means of bolts, not shown, passed through appropriate clear¬ ance holes 22 located in the longitudinal centre line of the fixture across the adjacent edges of mat webs 14 and 15. The upper side of the fixture is provided

with raised pattern 23 ensuring that it is non-slip. On the upper side above sections 20 the fixture has grooves 24 for the drainage of treatment fluid. The longitudinal edges of the fixture are sloping in order to present the least possible resistance against rolling on the mat.

Fixture 19 does not need to extend throughout the length of the web but in dependence on the weight of the mat, the nature and the type of the treatment to be effected, it may be a composite of short rail sec¬ tions uniformly spaced apart.

In order that the mat is able to effect drainage of the treatment fluid it is required that the adjacent layer is sloping in the direction of the grooves. This is generally the case when unfolding the mat on flight taxi strips, the taxi strip having a certain inclina¬ tion in order to drain off rainwater. The arrangement of a mat on such a taxi strip merely necessitates the mat webs being unrolled and fastened to each other and to the subjacent layer by means of fixtures 19 as described. Trenches 16, e.g. with associated gratings 17, are provided along the circumference to the mat from which the treatment fluid is discharged.

Fig. 4 illustrates a cement-cast collection trench 16 but in case of a smaller mat made in one piece, it may be sufficient along the circumference of the mat to provide a trench which at a single point is for instance extended to the edge of the mat where a discharge well may be arranged.