RU2791626C2 - The composition of the mixture to create a sub-ballast protective layer of the roadbed - Google Patents

Abstract

FIELD: railway track superstructure.

SUBSTANCE: invention relates to the railway track superstructure, in particular, to the compositions of mixtures for creating a sub-ballast protective layer of the roadbed. The mixture contains components at the following ratio by weight%: ballast weed - 80-90, crushed crushed stone from ballast - 1-10, cement-based hydraulic binder - 3-5, cement modifier - 0.3-0.5, water - 6-8.

EFFECT: invention enables to increase the modulus of deformation of the sub-ballast protective layer increases.

2 cl

Description

The invention relates to the field of railway transport and can be used to create a protective layer under the ballast during the renewal and cleaning of the ballast layer of the rail track.

It is known that one of the effective methods of strengthening the main area of the subgrade of the railway track in case of its deformation in the form of ballast splashes and ballast recesses, leading to rail track disorders, is the filling of under-ballast protective layers (Journal "Railway Transport", No. 6, 2013, pp. 55-56). At the same time, as a material for creating such a protective layer under ballast, a mixture of crushed stone, gravel and sand, artificially prepared at crushed stone plants, is used, a strictly specified ratio between fractions of different particles (Instruction for the installation of under-ballast protective layers during the reconstruction (modernization) of the railway track, approved by order of JSC Russian Railways dated December 12, 2012 No. 2544r). This mixture is delivered in large volumes to the place where the under-ballast protective layer is laid over considerable distances by rail in trains of specialized wagons, which causes significant financial costs, leads to a long time for the delivery of material and the need to maintain rolling stock from specialized wagons, which seriously reduces work efficiency.

Known, adopted as a prototype, a patent for the invention RU No. 2776165 class. E01B 27/10, publ. 07/14/2022, the plan of which is aimed at the maximum use of the materials available in the composition of the railway track when backfilling the sub-ballast layer. The composition of the mixture for creating a sub-ballast protective layer of the subgrade of the prototype includes weed, crushed crushed stone from the ballast prism of the track and water. The entire cut top layer of ballast is divided into cleaned crushed stone and weed, part of the cleaned crushed stone is fed to the crushing plant for recycling, and the material for the protective layer is prepared by mixing the weed with crushed crushed stone, which is moistened and laid on the cut surface of the subgrade.

Thus, with such formation of the under-ballast protective layer, a reduction in the cost of work is achieved by reducing the volume of material removed and laid. However, the disadvantages of this composition of the mixture for creating a sub-ballast protective layer include the fact that its required deformation parameters depend on the initial grain composition of the crushed stone being cleaned, the presence of fine particles and moisture in it, which are different for different areas and therefore each time it is required to determine the necessary ratio between the weed crushed stone and their moisture to obtain the required quality of the material with a high modulus of deformation, and in some cases this cannot be achieved.

The objective of the proposed technical solution is to ensure the required quality of the under-ballast protective layer prepared on the track machine during the cleaning of crushed stone with a high deformation modulus, regardless of the initial parameters of the cleaned crushed stone.

This technical result is achieved due to the fact that in the inventive composition of the mixture to create a sub-ballast protective layer of subgrade containing weed, crushed gravel and water, in contrast to the prototype, it additionally contains a hydraulic binder based on cement and a cement modifier based on polymer-mineral additives at the following ratio wt.%:

ballast weed - 80-90,

crushed crushed stone from ballast - 1-10,

hydraulic binder based on cement - 3-5,

cement modifier - 0.3-0.5,

water - 6-8.

In addition, the cement modifier consists of a mineral part and a polymer part in wt.%:

mineral part based on products of amorphous silicon dioxide, calcium and sodium salts - 90-95,

a complex of redispersible polymers based on polysaccharides - the rest.

The content of the ballast weed is the basis of the mixture, it has a granulometric composition that has developed during the operation of the track. If this composition is optimal, that is, its composition contains the minimum number of pores, then it is taken as a basis. If the number of pores in the composition of the weed ballast increases, then crushed crushed stone is used to control the optimal composition, thereby reducing the number of pores. The amount of crushed gravel is selected in an amount from 1% to 10%. With a larger amount of crushed stone, the consumption of binder and modifier increases, increasing the cost of the mixture.

Hydraulic binder based on cement in the amount of 3-5% is also due to the porosity of the mixture of ballast weed and crushed stone. The use of a cement-based hydraulic binder less than 3% leads to a decrease in the physical and mechanical characteristics of the mixture being strengthened, reduces frost resistance and resistance to cyclic loads. Increasing the flow of hydraulic binder above 5% increases the stiffness of the mixture and creates the risk of cracking.

The cement modifier (polymer-mineral additive) is included in the composition of the mixture in an amount of 0.3-0.5% and is used to correct the properties of cement, increasing its physical and mechanical characteristics, reducing indicators such as brittleness and cracking, adjusting the start time and end of setting of the mixture. The amount of modifier less than 0.3% does not affect the change in the characteristics of the cement and the mixture as a whole. The amount of modifier more than 0.5% stops the growth of indicators and the characteristics remain the same as with the amount of modifier in the mixture equal to 0.5%.

The modifier consists of 90-95% products based on amorphous silicon dioxide, calcium and sodium salts, which reduces the number of contracting (technological) pores of the mixture; as well as a polymer part based on surfactants and redispersible polymers, which are regulators of water content, adhesive properties and the formation of gel pores, providing mobility and hydrophobicity.

Thus, the rational use of the ballast material for laying the sub-ballast layer is ensured and at the same time its optimal quality is maintained in terms of a number of indicators.

The composition of the mixture can be prepared using existing materials, which confirms its compliance with the criterion of the invention of industrial applicability.

Claims (9)

1. The composition of the mixture for creating a sub-ballast protective layer of the subgrade, containing a weed, crushed gravel and water, characterized in that it additionally contains a cement-based hydraulic binder and a cement modifier based on polymer-mineral additives in the following wt% ratio: ballast weed - 80-90, crushed crushed stone from ballast - 1-10, hydraulic binder based on cement - 3-5, cement modifier - 0.3-0.5, water - 6-8. 2. The composition of the mixture according to claim 1, characterized in that the cement modifier consists of a mineral part and a polymer part in wt.%: mineral part based on products of amorphous silicon dioxide, calcium and sodium salts - 90-95, a complex of redispersible polymers based on polysaccharides - the rest.