RU2117090C1 - Method for construction of road base - Google Patents

Abstract

FIELD: construction engineering. SUBSTANCE: this relates to road building technology and can be used in erection of ground bases for pavements of motor roads. According to method, needed ground is preliminarily subjected to grinding, then mixture is made of such components as ground, cement, and additive which is preliminarily passed through dies. Also included in mixture is solution of fiber-creating polymer taken in amount of 0.75-1.25% of ground mass. Realization of aforesaid method allows for reducing labour-intensity in construction of road bases with improving strength, shear-resistance, and cracking-resistance of pavement erected on thus constructed road bases. EFFECT: higher efficiency. 1 dwg

Description

 The invention relates to road construction and can be used in the device of the bases of the pavement of roads.

 A known method of erecting the foundations of pavement, including grinding the soil, the introduction of cement into the soil, mixing the soil with cement, followed by moistening the mixture to optimal humidity and its compaction [1].

 The disadvantage of this method of erecting the foundations of pavement is that the foundation of the road does not work with equal strength, since it is impossible to evenly distribute inorganic binder on the ground, which relates to the funded material. The base has low crack resistance, which is due to the shrinkage of the strengthened soil during hardening.

 A known method of erecting the base of pavement, including the preparation of a mixture of soil, cement and an organic binder with its moisture to the optimum humidity, transportation and laying of the finished mixture in the base with its compaction [2].

 In this method, the mixture is prepared in two stages, first, the soil is mixed with cement, moistened and granules are formed, after which the granules are coated with an organic binder, and the granular mixture is laid in the base and compacted before the cement sets.

 The disadvantages of this method is the high complexity of the work, due to the need to obtain granules and coating them with an organic binder. The strength of the base is reduced if the mixture is not laid and compacted before the cement sets.

 Closest to the invention in technical essence and the achieved result is a method of erecting the base of pavement containing grinding soil, preparing a mixture of soil, cement and additives with moistening it to optimal humidity, leveling the mixture and compacting it [3].

 In this method, the preparation of the mixture is carried out by a road mill in two stages: first, an additive, for example fly ash, is introduced into the soil and mixed with soil, then cement is introduced and mixed again.

 When implementing this method, to give the cement soil increased strength, a denser structure is provided by introducing an additive in the form of fly ash, which serves as a filler of intergranular voids of the soil. In the combination of fly ash and cement, it plays the role of an active hydraulic additive.

 The disadvantages of the prototype method is the high complexity of the work associated with the implementation of work on the preparation of the mixture using a road mill by mixing on the road. Fly ash is characterized by increased porosity due to the formation of the inner surface of the pores during the combustion of solid fuels. As a result of getting into the pores of water, the frost resistance of the base decreases.

 Another significant drawback is that the cement-ash binder has a slow process of structure formation. The most intensive increase in strength in the soil treated with cement with the addition of fly ash occurs in the range of 90 - 120 days.

 The task is to reduce the complexity of the work when implementing the method with improving the strength characteristics of the base, contributing to an increase in crack resistance and shear stability of the base of the pavement.

 The problem is solved in that in the known method of erecting the foundation of pavement containing crushing the soil, preparing a mixture of soil, cement and additives with moistening it to optimal humidity, leveling the mixture and compacting it, a fiber-forming polymer solution previously passed through spinnerets is introduced into the amount of 0.75 - 1.25% of the mass of soil.

 The proposed method allows to increase the strength, shear resistance and crack resistance of the base due to the introduction of a solution of fiber-forming polymer in the base material in the form of continuous elementary streams. The chemical fibers formed from them have a considerable length, while the chemical fibers have the ability to combine with each other at the points of contact and distribute in the base material, forming strength spatial structures, each of which is associated with another of the same structure. As a result of this, a single spatial strength structure (lattice) is formed in the base material, which binds a large volume of mineral materials in the unit of structure. Due to the formation of the integrated spatial strength lattice, a better load distribution and its transfer to a large base volume occurs. The optimal amount of injected solution of fiber-forming polymer is 0.75 - 1.25% by weight of the soil. The introduction of a polymer solution of less than 0.75% by weight of the soil is not sufficient for the formation of a spatial lattice of fibers. The introduction of a solution of more than 1.25% by weight of the soil leads to the formation of a spatial lattice, which has a size smaller than the grain size, while the strength properties remain unchanged. Therefore, the use of a polymer solution of more than 1.25% by weight of the soil is not economically feasible and does not increase the strength of the base.

 The drawing shows a diagram of the installation for the construction of the base of pavement on the basis of the soil mixing machine D-391B [4].

 The installation comprises a cultivator 1, a unit for supplying cement and water, a unit for supplying a solution of fiber-forming polymer, a mixing unit, a leveling unit and compaction of the mixture.

 Ripper 1 is a ripping rotor that rotates along the machine. The direction of movement of the machine is indicated by arrow 14. The cement and water supply unit includes a powder binder dispenser 2 for dispensing and supplying cement to the soil 3, a water supply tank 4 and a distribution pipe 5 for supplying water to the soil. The fiber-forming polymer solution supply unit comprises a supply container for a fiber-forming polymer solution 6, a metering pump 7 for dispensing the solution, dies 8, which serve to separate the total precisely dosed stream of the polymer solution into separate elementary streams. The mixing unit contains a milling rotor 9, which rotates against the machine in the opposite direction to the rotation of the cultivator 1. The milling rotor transfers the crushed soil to the mixing rotors 10 and 11. The mixing rotors 10 and 11 are a twin-shaft mixer, where rotor 10 is the front shaft of the mixer rotating along the machine, and the rotor 11 is the rear shaft of the mixer, rotating against the machine. The leveling and compaction unit of the mixture contains a closed common casing 12, inside of which there are working bodies for grinding the soil (cultivator 1) and mixing it with a binder (milling rotor 9, mixing rotors 10 and 11). The rear wall of the casing 12 distributes and adjusts the height of the outgoing mixture. The mixture is sealed with rear steered wheels 13, which simultaneously serve as pneumatic rollers.

 The process of building the foundation of pavement is as follows.

 The soil is transported to the finished subgrade, profiled with a grader and compacted to 0.85 - 0.9 of the maximum density to facilitate the work on grinding the soil. Cement is supplied to the batcher of powdered binders 2 through a hose from a cement truck. A pre-filtered solution of fiber-forming polymer is fed into a supply container 6, and water is supplied to a container 4. With the translational movement of the machine, the cultivator 1 crushes the soil 3. The polymer solution from the tank 6, dosed by the metering pump 7 and passed through the dies 8 is introduced with the simultaneous continuous introduction of cement from the powder binder batcher 2 in front of the rotor 1, and the water is introduced through the distribution pipe 5 in front of the rotor 10. The mixture is mixed with rotors 9, 10 and 11. The rear wall of the casing 12, the mixture is distributed with a given height and sealed with rear wheels 13.

 In the process of mixing the components with the rotors 9, 10, 11, a cement-soil mixture is formed, reinforced with trickles of polymer, from which the fibers are formed. Chemical fibers bind mineral particles not only with particles surrounding it (short-range order coupling), but also with particles distant from a given particle by several rows of other particles (long-range order bond). Fibers form a spatial lattice in the material, which covers all the mineral particles that make up the mixture, which significantly increases the strength characteristics of the mixture. All operations on the construction of the foundation of pavement are performed in one pass of the soil mixing machine, which allows to reduce the complexity of the work.

Sources of information
1. Instructions for the use of soils reinforced with cementitious materials for the construction of bases and coatings for roads and airfields, CH 25-74, M., 1975, p. 51-56.

 2. Copyright certificate N 1310467, cl. E 01 C 3/04. The method of construction of the foundation of pavement, prior. 10.21.83.

 3. Instructions for the use of soils reinforced with cementitious materials for the construction of bases and coatings for roads and airfields. CH 25-74. - M., 1975, p. 51 - 56.

 4. Machines and equipment for the construction of pavements. Gorovoy G.M., Liberman M.A. - M., Transport, 1975, p. 44 - 64.

Claims (1)

 A method of erecting a pavement foundation, comprising crushing the soil, preparing a mixture of soil, cement and additives, moistening it to optimal humidity, leveling the mixture and compacting it, characterized in that a solution of fiber-forming polymer is preliminarily passed through filters in an amount of 0, 75 - 1.25% of the mass of soil.