RU2364675C2 - Method for repair of asphalt concrete coats in winter conditions and composite mixture of materials for its realisation - Google Patents

Abstract

FIELD: construction, road engineering.

SUBSTANCE: invention is related to the field of motor roads with asphalt concrete coat, in particular, to preventive repair of defects and pits on road surface. Method for repair of asphalt concrete coats in winter conditions consists in production of pothole filling repair of road surfaces at temperature of air up to -10°C with hot asphalt concrete road mixture based on viscous or liquid road bitumens, which is laid into previously heated defect area. Repair of coats at air temperature of up to -10°C is carried out in the following sequence: defect area of coat is treated with 30% aqueous solution of calcium chloride as 0.5 litre of solution per one square metre of treated surface, treated area is filled with preset amount of liquid sodium glass that additionally contains 8% of carbamide, specified amount of previously prepared dry mixture of sand and cement is poured into liquid glass filled into pit, moreover, as a result of their mixing, mixture of materials is immediately stiffened and hardened, afterwards surface of repaired coat section is treated with 30% aqueous solution of calcium chloride, is coated with liquefied bitumen and powdered with sand. Composite mixture of materials is also described, which is hardened on above-described method.

EFFECT: creation of method for repair of asphalt concrete coats in winter conditions.

2 cl

Description

The invention relates to the field of roads with asphalt concrete coating, in particular to the preventive repair of defects and pits on the surface of the road. During the operation of the road, defects on the road surface inevitably appear.

The most characteristic damage to asphalt concrete pavements are potholes, edge damage, breaks and other damage that occur in the spring, autumn and winter periods of the year at low positive air temperatures. Especially intensive is the destruction of the coating during freeze-thaw cycles of asphalt concrete.

At present, patching of road asphalt concrete pavements is recommended at air temperatures in the spring of at least + 5 ° C and in autumn at + 10 ° C. And with the onset of lowered air temperature to -10 ° C, asphalt concrete pavements are recommended to be repaired with mixtures based on viscous or liquid road bitumen grade BND-200/300 or SG-130/200, see "Guidelines for the repair and maintenance of public roads" , M., Rosavtodor, 2004 [1].

In accordance with these recommendations, when repairing asphalt concrete pavements in winter, it is necessary to warm up the defective place, and then place the hot asphalt mixture in this place.

However, this method of repair in winter conditions has the following disadvantages:

1) there are no necessary small-sized installations for preparing on-site repair of hot asphalt mixtures in the winter;

2) pre-prepared asphalt mixes in the warm season with the onset of negative temperature cannot be warmed up due to the lack of special plants, and if the mixture is warmed up, it is done in a makeshift way and in minimal quantities;

3) the delivery of the hot mixture to the place of repair is carried out, as a rule, in vehicles not adapted for heat preservation, as a result of which the mixture cools quite quickly by the time of its compaction (in the best case, the compaction coefficient is 0.95-0, 96);

4) as a result of the above factors, poor repair quality is observed and, as a result, short service life of repaired defective places, associated, as a rule, primarily with strong dependence on weather conditions and poor preparation of such places for repair, namely:

- laying the mixture without heating the defective place due to the lack of heating installations;

- laying the mixture on snow, a damp surface or in water without priming and other violations of the rules;

- insufficient compaction of the asphalt mix due to the difficulty in delivering compaction agents and work in winter conditions.

The aim in the development of the invention is to create a method (technology) for repairing asphalt concrete coatings in winter conditions and to create a composite mixture of materials for implementing this method.

The specified goal and technical result are implemented as follows. In the present invention, patching of asphalt concrete pavements under winter conditions at an air temperature of -10 ° C is carried out in the following sequence: the defective coating site is treated with a 30% aqueous solution of calcium chloride at the rate of 0.5 l of solution per square meter of surface to be treated; a predetermined amount of liquid sodium glass is poured into the treated area; a predetermined amount of a previously prepared dry mixture of sand and cement is poured into the liquid glass poured into the hole, and as a result of their mixing, an instant setting and hardening of the mixture of materials occurs; the surface of the repaired coating area is treated with a 30% solution of calcium chloride, and then this surface is coated with liquefied bitumen and sprinkled with sand.

Moreover, a composite mixture of materials for implementing this method of repairing asphalt concrete coatings in winter conditions contains the following materials in% by weight:

- liquid sodium glass with a density of at least 1.3 g / cm ³ containing additionally at least 8% urea - 17%;

- a pre-prepared dry mixture of sand with cement, which contains 85% sand and 15%, at least Portland cement - 83%.

As a close analogue to the proposed method, you can take "Methodological recommendations for the repair and maintenance of public roads", M., Rosavtodor, 2004 [1].

In the present invention, as a repair mixture for patching an asphalt concrete coating, instead of a hot asphalt concrete mixture, a liquid-glass mixture of materials is used, consisting of two components: liquid sodium glass in an amount of 17% by weight of the entire mixture and a previously prepared dry mixture of sand and cement in an amount of 83% of mass of the whole mixture. When they are combined and mixed in a defective coating area, instant setting and hardening of materials occurs.

And this is extremely important and effective when repairing asphalt concrete pavements in winter conditions. In this case, the preparation of a liquid-glass mixture must be done using the “back impregnation” method, that is, a dry mixture of sand and cement is poured into liquid glass, which does not even require mixing; in this case, an instant setting and hardening of the mixture of these materials takes place.

To lower the crystallization temperature of liquid glass to -10 ° C, an anti-frost additive, for example urea (urea), is introduced into liquid glass in an amount of, for example, 8% by weight.

The second component of the repair liquid glass mass - a dry, pre-prepared mixture of sand and cement - contains 85% sand and 15%, for example, Portland cement.

The proposed method for repairing asphalt pavements in winter conditions is as follows.

One of the necessary technological operations in the repair process is the treatment of the defective place with a 30% aqueous solution of calcium chloride (CaCl ₂ ). This operation allows melt ice and snow deposits and ensures good survival of the repair material to asphalt concrete. In this case, the flow rate of the solution should be at least 0.5 liters per square meter of the treated surface.

Then, in a pothole prepared for repair, based on its capacity, a predetermined and necessary amount of liquid glass is poured in an amount of 17% of the total mixture weight, into which a predetermined amount of a previously prepared dry mixture of sand and cement in an amount of 83% of the total mass is filled mixtures, and as a result of their mixing, instant setting and hardening of the mixture occurs.

After leveling the surface of the liquid-glass repair mass, the entire surface of the repaired coating area is treated with a 30% solution of calcium chloride, and then this surface is coated with liquefied bitumen and sprinkled with sand. Liquefied bitumen is prepared directly at the place of work at temperatures up to -10 ° C, for which viscous bitumen is diluted with gasoline in an amount of up to 40% by weight of bitumen.

To open the movement of automobile transport on the repaired section of the road according to the proposed method of repair was sufficient and possible only 15-20 minutes.

Almost according to the standards for opening the movement of vehicles it is necessary that the repair material gain compressive strength of at least 0.6 MPa in accordance with the requirements of the document "ODN 218.046-01. Design of non-rigid pavement" [2].

Analysis of the hardening kinetics of the repair mixture in the proposed composition of materials showed that the required strength of 0.6 MPa at an air temperature of -10 ° C is provided after 15-20 minutes. After 7 days, the strength of this repair mixture (material) reaches 2.5 MPa, and at the age of 14 days - 2.6 MPa.

Dry sand and cement mixtures in a predetermined proportion of 85% sand and 15% cement are preliminarily prepared by forced mixing of the components in a mixer. Dry mixes are stored in sealed kraft bags prior to the start of work.

It is advisable to prepare dry mixtures at lower material costs in advance before the onset of negative air temperatures, which leads to the creation of certain reserves of the mixture.

Studies of the influence of the length of time and storage conditions of dry sand and cement mixtures on their activity yielded a significant positive result. For this, batches of dry mineral mixtures with an initial moisture content of 2% were stored in hermetically sealed kraft bags at an air temperature of + 22 ° C for 28 days.

The activity of the mineral mixture after storage in kraft bags for 28 days increases the compressive strength of the prepared liquid-glass working mixture and increases from 2.1 MPa after the first day of storage to 4.1 MPa after 28 days of storage. Therefore, dry mineral mixtures prepared from the proposed components, it is desirable and necessary to withstand at least 28 days prior to their use in sealed packaging.

Thus, the proposed method for repairing asphalt pavements in winter conditions has a number of positive qualities compared to known methods, namely:

- manufacturability and ease of preparation of repair mineral mixtures at positive and negative air temperatures;

- availability in the material and technical support of the components of the mixture materials;

- a sufficiently large duration of storage prior to laying (mixing) of previously prepared repair mineral mixtures;

- transportation of repair mixtures to the place of work on any type of transport;

- laying repair mixtures in a defective place without sealing as a "cast";

- reducing the dependence of the use of this technology on weather conditions;

- a significant increase in the service life of the repaired area of asphalt concrete pavement;

- a quick set of strength in the early stages (already in the first hours) of the repair material;

- reduction of harmful effects on workers and the environment from the applied components of the repair material;

- relatively low cost of repair work.

The proposed method for repairing asphalt concrete pavements and a composite mixture of materials were tested with a positive result in the experimental sections of the Kuybyshev-Vengerovo highway - the border of the Omsk Region in the winter periods of 2006 and 2007.

Information sources

1. "Guidelines for the repair and maintenance of public roads", M., Rosavtodor, 2004

2. "ONE 218.046-01. Design of non-rigid pavement."

Claims (2)

1. A method of repairing asphalt concrete pavements in winter conditions, which consists in the patching of pavements at an air temperature of -10 ° C with hot asphalt concrete mix based on viscous or liquid bitumen paved in a preheated defective place, characterized in that the coating repair at ambient temperature to -10 ° C in the following order: place the defective coating is treated with 30% aqueous solution of calcium chloride at the rate of 0.5 liters of solution per 1 m ² obrabatyv of the surface to be washed, a predetermined amount of liquid sodium glass containing at least 8% additional urea is poured into the treated place, a predetermined amount of a previously prepared dry mixture of sand and cement is poured into the poured liquid glass, and as a result of their mixing, instant setting and hardening the mixture of materials, after which the surface of the repaired coating area is treated with a 30% aqueous solution of calcium chloride, coated with liquefied bitumen and sprinkled with sand . 2. The composite mixture of materials cured in the method according to claim 1, containing the following materials,% by weight:
liquid sodium glass with a density of at least 1.3 g / cm ³ containing additionally at least 8% urea - 17%;
a pre-prepared dry mixture of sand and cement, which contains 85% sand and 15%, at least Portland cement - 83%.