The object of the invention is a method for adding liquid material into a wooden pole as defined in the preamble of claim 1, and a wooden pole treated with liquid material as defined in the preamble of claim 6, and also use of the wooden pole treated with liquid material as defined in claim 11.

The term liquid material in the context of this description refers to a fluid solution, mixture or mass in which one or more fine-grained powdery and/or granular substances, such as e.g. cement and, if necessary, various other additives, are mixed into a liquid, such as into water. The wooden poles according to the invention are well suited to applications in which good resistance to decay is needed. In this case the wooden poles according to the invention are well suited to be e.g. electricity poles, telephone poles and lighting poles as well as e.g. the wooden support poles of bridges or other structures, and also to be outdoor fittings and garden furniture.

Various wooden poles, such as electricity poles, telephone poles and lighting poles as well as e.g. the wooden support poles of bridges, and also outdoor fittings and garden furniture, are generally impregnated with some impregnating agent so that the pole would not decay so quickly. These types of poles are prone to decay because they are in continuous contact with the ground and/or water. It is known in the art that e.g. C, CC and CCA impregnating agents are used, which contain poisonous substances that are harmful to the environment, such as chrome, copper and arsenic. Over time the impregnating agent leaks into the ground and the soil is polluted. For example, arsenic, chrome and copper dissolve from CCA-impregnated wood into the soil and water during use, and copper dissolves from C-impregnated wood. These elements are extremely poisonous to many organ- isms after they are released into the environment. They do not decompose but instead accumulate in the environment and in organisms. A user of longlife wood can e.g. be subjected to substances harmful to the health contained in impreg- nated wood when handling and working with wood that has been, in particular freshly, impregnated in this way. Correspondingly, children might be subjected to possible skin contact with impregnated wood in built playgrounds and/or via impregnating agents rinsed into sand.

The European Union, among others, has in fact nowadays prohibited the use of these impregnating agents for impregnating wooden poles. In addition, these impregnating agents do not protect a pole from decay for long enough, owing to which wooden poles must be replaced for new ones e.g. at intervals of approx. 25-35 years. If the poles were to last longer, they would not need to be replaced so often, in which case the replacement costs would be saved. One impregnating agent used in wooden poles is creosote, which contains e.g. coal and tar and also possibly many other substances. Creosote is also a substance that is harmful to the environment and when it leaks from a pole over time it pollutes the soil. Creosote is hazardous to the health in particular because of the carcinogenic and mutagenic PAH compounds it contains. When it comes into contact with the skin it might cause stinging and redness and might also irritate breathing. Creosote protects wood from decay for slightly longer than the other aforementioned impregnating agents, but poles impregnated with creosote also must always be replaced with new ones at certain intervals. When wood is impregnated with creosote, it must first be dried for about one year and after impregnation it must be allowed to dry again for about a year. A problem resulting from this long preparation time is that the poles must be in storage for about two years for a possible need. Another problem is that poles impregnated with creosote smell unpleasant, owing to which it is preferable not to use them near residential areas.

Another problem is also that climbing on poles impregnated with the aforementioned poisonous substances requires appropriate protective equipment, which increases the costs e.g. in servicing situations. These types of impregnating agents do not either prevent the intrusion of different insects and pests into the pole. In certain parts of the world e.g. termites might destroy these types of wooden poles. Also woodpeckers can make cavities in these types of wooden poles when they are searching the poles for small animals that have penetrated them.

A further problem is that the aforementioned impregnating agents leak over time downwards in the pole, in which case the concentration of impregnating agent in the top part of the pole decreases and the top part is more easily susceptible to decay. Downward leaking of the impregnating agent also pollutes the soil, as already mentioned.

Also e.g. composite poles or steel poles are used instead of wooden poles. A problem with these types of poles, however, is that they are considerably more expensive than wooden poles. In addition, they cannot be climbed with the same tools as with wooden poles, in which case in a servicing situation special tools are needed, which increases costs. One drawback is that steel poles weigh a lot, in which case large and efficient machines, which cannot be used in all locations, are needed to handle them.

The aim of this invention is to eliminate the aforemen- tioned drawbacks and to achieve an inexpensive, simple and also fast method for treating a wooden pole with a liquid impregnating agent, such as with a cement-based concrete mixture for e.g. concreting and impregnating the wooden pole. Additionally the purpose of the invention is to achieve a wooden pole treated with a liquid impregnating agent, e.g. concreted, which is not detrimental to the en- vironment, to people or to animals and which lasts a long time without decaying. Yet another aim of this invention is to achieve a wooden pole treated with a liquid impregnating agent, e.g. concreted, which has a long service life and is well suited to different applications. The method according to the invention is characterized by what is disclosed in the characterization part of claim 1. Correspondingly, the wooden pole treated with liquid impregnating agent, e.g. concreted, according to the invention is characterized by what is disclosed in the characterization part of claim 6, and use of the aforementioned wooden pole is characterized by what is disclosed in the characterization part of claim 11. Other embodiments of the invention are characterized by what is disclosed in the other claims. One advantage of the solution according to the invention is that the concreted wooden poles according to the invention, e.g. impregnated with fresh concrete containing cement, do not contain poisonous substances and are not therefore detrimental or dangerous to the environment, to people or to animals. Another advantage is that wooden poles according to the invention last a very long time without decaying. Another advantage also is that the poles do not ignite and burn easily. Another advantage is also that the poles do not need to dry for long after impregnation, so they can be taken into use quickly, in which case large and expensive warehouses are not needed either. A further advantage is that different insects and pests are not able to penetrate to inside the concreted pole. Another consequence of the structure is that birds, mainly woodpeckers, are not able to make holes in the poles when they try to find nutrition in them. A further advantage is that in servicing situations protective gear is not needed to protect against poi- sonous impregnating agents and in addition prior-art tools can be used for e.g. climbing a pole, in which case there are savings in costs. A further advantage is that the poles according to the invention do not discolor the objects with which they are in contact. One advantage is also that the concrete hardened from fresh concrete containing cement does not leak downwards in the tissue of the wood, in which case no foreign substances get into the earth from the wood .

In the following, the invention will be described in more detail by the aid of an example of its embodiment with reference to the attached drawings, wherein Fig. 1 presents a side view of a truncated wooden pole to be concreted with the method according to the invention,

Fig. 2 presents a part of a truncated wooden pole to be concreted with the method according to the inven- tion, as a magnified transverse section of the wood

Fig. 3 presents a part of a truncated wooden pole to be concreted with the method according to the invention, as a magnified longitudinal section of the wood, and

Fig. 4 presents a side view of a truncated wooden pole to be concreted with the method according to the invention and covered with a thin concrete layer on its bottom end. The basic idea of the invention is to replace the impregnating agents used before with a very fine-grained material that raises the pH value of wood. According to the embodiment, one such material is very fine-grained cement, either on its own or with various additives suitably mixed into it. A wooden pole is impregnated by injecting, by capillary action or with some other suitable method with a so-called liquid microcement mixture, the pH value of which is ex- tremely high. The mixture can also be called a fine concrete mixture. The mixture is compressed or absorbed into the tissue of the wood and inside the pores of the wood and when the additives of the mixture react with each other the liquid mixture hardens as it dries into concrete or into a material corresponding to concrete, in which case the wooden pole becomes stronger and harder than pure wood and is difficult to decay and burn.

In the method according to the embodiment, a wooden pole is impregnated with a cement-based mixture, for which procedure the term "concreting a wooden pole" is used in the description of the example hereinafter. For the same reason, in this example the terms "concreted wooden pole" or "wooden pole to be concreted" are used hereinafter to refer to a wooden pole thus treated.

Fig. 1 presents a side view of a wooden pole 1 to be concreted with the method according to the invention, cut shorter for the sake of illustration. In this embodiment the wooden pole 1 is concreted with just cement mixed into water, which forms weak running fresh concrete, i.e. a concrete solution, or with a concrete solution mixed from water, with cement and with suitable additives, by injecting the solution under pressure from the end of the wooden pole 1 to inside the wooden pole in the direction of the arrow A and by letting the solution harden into fine-grained concrete inside the wooden pole 1.

Fig. 2 presents a small part of a truncated wooden pole 1 to be concreted with the method according to the invention, as a magnified transverse section of the wood. Fig. 2 presents an example of the tracheids 2 of a conifer tree, which tracheids are separated from each other by cell walls 3. The tissue of the trunk of the tree, including the tracheids 2, take care of the intake of the liquid and nutrition of the tree from the soil to the treetop, so the tis- sue in a wooden pole 1 can also be filled with liquid fresh concrete, or with mixtures of it, if the grain size of the fresh concrete is small enough. Fig. 3 presents a small part of a wooden pole 1 to be concreted with the method according to the invention, as a magnified longitudinal section of the wood. In conifer trees most of the tissue of the wood is long fibers, tra- cheids, i.e. elongated cells 2, the length of which in e.g. a spruce tree ranges between 1-4 mm. Correspondingly, the diameter of the tracheids 2 of conifer trees, such as of a spruce tree, ranges between 20-40 m.

Fig. 4 presents a side view of one truncated wooden pole 1 to be concreted with the method according to the invention and covered with a thin concrete layer 6 on its bottom end, which concrete layer 6 is cross-sectioned for the sake of illustration. In addition to the filling of the wood tissue of the pole, the durability of the wooden pole 1 can be improved by coating the bottom part of the wooden pole 1 up to a certain necessary height with suitably mixed liquid fresh concrete, which can be e.g. so-called waterproofing plaster with a pH value of greater than 9. The coating 6 can be made e.g. by dipping the bottom part of the wooden pole 1 one or more times in the aforementioned liquid concrete mixture such that the thickness of the coating 6 is finally e.g. approx. 1-3 mm, suitably e.g. approx. 2 mm, on both the cylindrical surface of the wooden pole 1 and on the butt end of the wooden pole 1. The pore structure of the coating layer 6 is preferably such that water outside the wooden pole 1 is not able to penetrate through the coating 6 into the wooden pole 1, but moisture already in the wooden pole 1 is able to get out of the pole through the coating 6 and the. wooden pole 1 dries under the coating. The fresh concrete to be used in the method according to the invention, as a liquid material and suitably mixed, i.e. freshly mixed concrete, is comprised of a material having a grain size that is preferably smaller than approx. one-third of the diameter of the tracheids 2 of the wooden pole. In this case the fresh concrete fills the tissue and the pores of the wooden pole 1 to be concreted well before it hardens inside the wood. The grain size of the cement granules 4 to be used in the concreting and of the additive granules 5 to be used as agents is in this case typically e.g. between approx. 4-12 μπι, suitably e.g. between approx. 5-10 μπι and preferably e.g. between approx. 6-8 μιη.

Most of the mixture used for concreting is e.g. cement granules 4 dissolved in water, the grain size of which granules is very small, as mentioned above. In this case the cement is so-called microcement, the particles 4 of which penetrate well into the tissue of the wooden pole 1 to be concreted and between the grains and the pores. In addition, in the concreting mixture there can be different additives comprised of small grains 5, which make it possible e.g. for the concreting mixture not to harden too fast and also speed up the penetration of the concreting mixture into the wood. In addition the additives improve the strength of the wooden pole. In this case it can be said that the concreting mixture used, i.e. fresh concrete, is so-called fine concrete.

One essential feature is that the pH value of the concret- ing mixture is extremely high and the aforementioned pH value stays extremely high in the wooden pole 1 for a long time, because at least the mass composed of cement particles 4 has hardened into concrete or into a substance like concrete in the tissue of the wood, in which case the ce- ment particles 4 remain in the tissue in their position well without leaking downwards. In this case decaying of the wooden pole 1 is prevented. The pH value of the con- creting mixture is e.g. greater than 9, preferably between 10-14 and suitably e.g. 11, 12 or 13.

In addition to cement 4, e.g. one or more than one together of the following materials are used in the concreting mixture as a blend component and as an additive 5: coal ash, granulated blast furnace slag or other suitable slag, silica gel, crushed glass, crushed stone, lime and pulverized charcoal .

According to one preferred embodiment the wooden pole 1 to be concreted with liquid fresh concrete is heat-treated before the concreting phase. In this case the tissue of the wood swells, in which case the liquid concreting mixture is made to be absorbed into the wood better.

The concreted wooden pole 1 according to the invention comprises at least a tissue structure with pores, in which tissue and pores is at least hardened concreting mixture, i.e. fresh concrete, the grain size of which is smaller than approx. one-third of the diameter of the cells 2 and the pH value of which is e.g. greater than 9, preferably between 10-14 and suitably e.g. 11, 12 or 13. In addition to a concreting mixture implemented with just cement 4, in the tissue and pores of the wood there can also be a concreting mixture, i.e. fresh concrete, blended with an additive 5.

The concreted wooden pole 1 according to the invention is used in various applications, in which wood protected according to prior art against decay is used. In this case the concreted wooden poles 1 according to the invention are used e.g. as electricity poles, telephone poles and lighting poles and also as the wooden support poles of e.g. bridges or other structures, and also as outdoor fittings and garden furniture. It is obvious to the person skilled in the art that the invention is not limited solely to the embodiments described above, but that it may be varied within the scope of the claims presented below. Thus, for example, other alkaline substances than cement, e.g. silica gel, can be used to fill the tissue of a wooden pole.

Likewise it is obvious to the person skilled in the art that, in addition to the aforementioned grain sizes, also smaller or larger grain sizes of the basic material, i.e. of the cement or silica gel, as well as of the additives, than what is presented above can be used.

Likewise, it is also obvious to the person skilled in the art that the fresh concrete, or the hardening mass essentially corresponding in its pH value, does not necessarily need to contain cement as a binding agent, but instead some other suitable material can be a binding agent.