MATERIAL

Invention Field

[001] The present invention refers to a railway sleeper for construction of railroad lines which is produced with a new thermoset composite material comprising basically a mixture in a specific combination of sand, fine powder, one or more resins and synthetic, metallic, natural fibers, or mixtures among them.

[002] More specifically, the present invention refers to a railway sleeper produced in thermoset composite material to be used as support and fixation of rail tracks in the railways, as well as for other types of vehicles circulating on rails. Nevertheless, the same thermoset composite material of the railway sleeper according to the present invention may be used in other applications, such as, but not limited to them, the construction and furniture industry, among others.

[003] In the context of the present invention, composite means any type of material that employs in its composition at least two or more known materials and formulated in a proper, specific and suitable manner, aiming a certain application.

State of the art

[004] As well-known, presently there is a great technology advance aimed at meeting human needs and seeking the creation of new materials, as well as the combination of existing materials to meet the new feasibility requirements for the execution of modern projects in various areas, mainly in industries and in civil construction. This technological growth justifies fully the creation and existence of new composite materials.

[005] As a rule, the manufacture of a composite requires in its composition a agglomerating element that enables the mixing of the components, in general through a chemical reaction or through heat, between them or only one of them, originating the merger or union of the components of the mixture forming an unique compound, of rigid characteristics, or malleable, or flexible. In general, the binder can be thermoplastic or thermoset.

[006] When using the thermoplastic binder, the application of heat tends to change its shape and characteristics, melting or draining. When using the thermoset binder, its form and characteristics are maintained after curing, even at elevated temperatures.

[007] The current state of the art allows us to perceive the existence of thermoplastic and thermoset composites with differentiated composition and processes of production.

[008] The vast majority of the composites of the state of the art are produced by the process of pultrusion. This process produces continuous composite profiles consisting of a matrix of thermoset resins and reinforcement components, in general fibers. The process consists of pulling the fibers impregnating them in the matrix of resins through a spinneret or mold. Then, the spinneret or mold is subjected to a heating causing the hardening or curing of the resin in the polymerization process. The process requires accurate temperature control, as this is essential for obtaining uniform properties in the final product. The characteristics of the mold allow obtaining a certain profile geometry, as well as the desired surface finish. Despite the widespread use, the pultrusion process reveals quite sophisticated and slow production, placing the cost of the product at a high level.

[009] Thus, there is a need for a new thermoset composite material notably for the manufacture of railway sleepers for the construction of railway lines, which can efficiently meet all new technological requirements of the market, without limitations and efficiently.

[0010]Therefore, it is an objective of the present invention to provide a railway sleeper produced from a new composition of composite material that allows, for their new and perfected features of mechanical resistance, enormous gains regarding the increase of conditions to cope with technical solutions and performance in the current requirements, which even considering the similar materials of state of the previous technique was not possible, notably with the railway sleepers.

[0011] Further, it is an objective of the present invention to produce a railway sleeper or other industrial products of thermoset composite material provided by a mixing process of all the elements in a suitable mixer, being that, after prepared, said mix is discharged into a mold previously prepared for the operations of press and rapid curing of the mixture. Thus, according to the present invention, pre-molded pieces are produced comprising composite material with high productivity and involving simple and automated operations.

Description of the Invention

[0012]The railway sleeper of reinforced thermoset composite material according to the present invention is defined as being a composition comprising sand, fine powder, thermoset resin and fibers.

[0013] More specifically, the reinforced composite material according to the present invention comprises a mixture of, in percentage weight, about 30-50% of sand, about 15-30% of inert fine powder, about 20-30% of resin of thermoset resin, about 4-10% of fibers.

[0014]Typically, one or more thermoset resins can be used, but when only one is used, preferably is rigid or flexible polyester type.

[0015]The fibers used in the reinforced composite material according to the present invention may be metallic, carbon, glass or natural fibers, or mixtures among them, and the like that are compatible with other components of the reinforced composite material according to the present invention.

[0016] Preferably, glass fiber is used and, when utilized, preferably it is in yarn segments shape.

[0017] A preferential example of the formulation of reinforced composite material according to the present invention comprises a mixture of, in percentage weight, about 50% of dry sand, about 20% of coal ash of mineral coal, about 25% of thermoset resin, about 5% fibers. [0018] A percentage of about 5% by weight of fibers seems to be little but as generally said fibers have low specific weight, their volume is significant in the final product.

[0019] In the mixture comprising the reinforced composite material components according to the present invention a suitable mixer should be used, since the fibers will be in small length yarn shape, usually varying from 2 to 10 cm, and the mass with the gradual adding of said glass fibers becomes fairly consistent. One can consider that this is a "heavy mass" that should be properly blended. Typically, a Sigma-type mixer is employed, not excluding others.

[0020]A thermoset resin is preferably pre-accelerated and will start its catalyzation, that is, hardening reaction, at the time of mixing the components in the mixer and, further, for a period of time sufficient to prepare the mixture and, then transferring it to the mold for subsequent pressing.

[0021] Alternatively, the mixing of components may be subjected to injection molding processes.

[0022] Further, with the use of fibers in the composite material becomes possible to obtain higher mechanical resistances, not only in the compression, but mainly the traction of the molded product. In the event there are no said fibers, the agglutination resistance between the composition materials would be exclusively borne by the resin in anchorage with the sand. Differently, with the employment of fibers according to the present invention, the anchorage becomes a trinomial based on sand, resin and fibers, allowing greater resistances, especially the traction resistance, since the fibers will also be scattered in the horizontal direction along the body of the workpiece produced.

Tests and essays

[0023]The thermoset composite material according to the present invention was tested by mechanical tests of railway sleeper specimens, carried out by Laede - Laboratory of Acoustics and Dynamic and Static Tests, Sao Paulo, Brazil

(www.laede.com.br).

[0024]The materials tested were the railway sleeper monobloc of composite 10 and 1 1 , of wide gauge (1 ,600 mm), composed of elastic fixings with clamp. The sleepers were tested in tests to measure positive and negative moments in supports A and B, in the center of the railway sleeper, repeated loading (fatigue) and yanking of inserts. Table 1 summarizes the results of the tests carried out.

Table 1

[0025] In addition, tests were carried out in traction and compression assays with samples of the railway sleeper 1 1 and 12 (test specimens-CPs). Tables 2a- 2c below summarize the tests and the results obtained in the tests.

Table 2a-Essavs

Table 2B - Compressive strength

Table 2b- Tensile strength by diametral compression

[0026]The tests were performed according to the Standard Arema: 2015, Chapter 30, Part 4. In tests of positive and negative moments in the support and center of the sleeper, the approval was effectuated by the non-disruption of the material, since there is no cracking as in the concrete. In all tests the sleeper bore the applied loads. In the yanking test, all inserts supported the tensile load of 53.4 KN without any damage to the material and the insert. In the torque test, the inserts supported the torque of 339 N. m without the appearance of cracks, breaks or excessive deformation of the material.

[0027] In the trials performed, servo-hydraulic tutors were used, with a capacity of 250 kN, controlled by a system of its own; charge cell with equal capacity, calibrated according to ABNT NBR 8197:2012 Standard, respecting class I of ISO 7500-1 :2015; and displacement transducers, precision 10 ³ mm; rectifier for flattening the test specimens; hydraulic compression machine with digital display, from Solotest.

[0028]Thus, the tests described above demonstrate that the railway sleeper according to the present invention is suitable for a wide range of customers, considering that said railway sleeper exceeded, in much, the minimum values required by the aforementioned standard Arema: 2015 (Chapter 30, table 30-5- 1 ) ·

[0029]Thus, it can be affirmed that the composite material of the sleeper according to the present invention is apt to be employed in all railways for passenger trains, railways of light and medium loads (27.5 t/axle). In geographic terms, except for the railways for ore and heavy loads, all the others can be met, namely, the entire railway network of Europe and much of the rail network of Brazil, USA, Canada and Australia.

[0030] Furthermore, the reinforced composite material according to the present invention is environmentally friendly because it does not employ water in its composition, but important industrial waste, such as the ashes arising from the burning of the mineral coal or residue of powder ore, such as gravel powder, among others. Additionally, it is sustainable, since instead of being discarded after some kind of use, if applicable, it can be crushed and reused in the process of production of new pieces.

[0031]Thus considering, it becomes apparent to the technicians who are well- versed in the subject that the precast products manufactured with the reinforced composite material object of the present invention will be much more resilient and the designers may gain advantages in reducing dimensions, weight and costs in their projects, unreachable by other existing or proposed products on the market. It is especially suitable for various applications, and can be useful in replacing cement concrete in buildings, wooden sleepers on railroad, wood and glass in furniture and utensils, among other numerous applications, since it is totally waterproof, has low specific weight, high compressive and tensile strength, does not oxide with iron and steel and has high durability exposed to time.