MX2012001594A - Flexible paving structure for streets and roads, comprised of a stabilized inferior base and an upper laying pavement of reduced thickness. - Google Patents

Abstract

A paving structure designed preferably for the use in heavy traffic roads where said structure comprises at least two layers. One first inferior layer or base which makes the entire or almost the entire paving structure by means of a CBR > 100% and compressive strength > 20 Kg/cm2 which corresponds to a layer formed from the original existing soil treated by means of a physiochemical stabilization process; and one second upper layer corresponding to asphalt pavement or the like, having flexible performance and reduced thickness which provides none, or little, structure.

Description

FLEXIBLE PAVEMENT STRUCTURE FOR STREETS AND ROADS, COMPOSED OF A STABILIZED BOTTOM BASE AND A SUPERIOR ROLLER FOLDER REDUCED THICKNESS DESCRIPTIVE MEMORY FIELD OF THE INVENTION The present invention refers to a pavement structure with characteristics of stability, strength and improved impermeability, where said structure is composed of two layers: a lower one or base, which, given its physical-chemical structure, supports the most important stresses of transit; and by a superior or folder, of little thickness, destined to support the abrasive action of the traffic.

The main use of the pavement structure of the invention is in roads of high solicitation, both public and private, as well as in patios and industrial warehouses. Due to its advantages in cost and environmental sustainability, it is effective in mining, forestry, and electrical projects, whose paving was not available today at reasonable prices.

BACKGROUND The traditional asphalt roads are designed to withstand traffic stresses in each of the layers that make it up and, particularly, in the upper layers, a situation that implies having thick asphalt road folders, with the corresponding consequences in paving costs.

The present invention has its foundation in the increase of the supporting capacity of the grade of the road, using the actual material existing in the soil, to which solid and liquid elements are added so that due to the effect of chemical reactions, a soil relatively weak, improves its characteristics of stability, resistance and impermeability.

The base of the road or grade stabilized in this way, can take an important part of the traffic solicitations, so that the requirements of asphalt rolling folder are reduced exclusively to thin layers to support mainly the abrasive action of traffic.

The relevant load resisted by the floors is mainly shear or cut (t). The equation that governs this type of solicitations is: t = C + s Tg f where C, is the component of the shear strength given by the cohesion capacity of soil particles; Y where olg < > , is the component of the resistance to the cut given by the physical characteristics of the soil, that is, coefficient of friction between particles, granulometry and density.

Therefore, to produce an adequate stabilization of a certain soil, it must be treated through physical-chemical reactions, by incorporating solid and liquid additives that modify physical characteristics of the soil, such as granulometry, electric charges and others, so to increase its capacity to withstand shear stresses.

The available floors by themselves do not usually meet the quality requirements to be used as bases or flush. The process by which the soil is improved to meet the established requirements is called "Stabilization". In general terms, stabilization has been restricted to only one aspect of soil improvement: the replacement of poor quality material with other specially prepared material.

Mechanical stabilization consists of improving the properties of a soil by changing its graduation, which can be obtained by mixing two or more soils, adding a certain fraction or partial or total removal of some size by screening. This form of stabilization is the one traditionally used in a flexible pavement design. The disadvantages of this type of stabilization are related to the quality of aggregates and their availability. Many times the good quality aggregates are very far from the place of the work and this greatly increases the cost of this item.

Multiple publications of prior art patents have raised the possibility of stabilizing soils through chemical additives, for example, the Japanese patent JP2001 187885 addresses the problem of providing a cement base for the stabilization of soil that uses small separations of solid and liquid, which is strongly dispersed and cures them in a short time, even when it is injected inside the water, producing a cured product with great resistance and generating a consolidated body of large volume; performing a stabilization of the soil using the chemical. The solution provides a base of chemical liquid cement for stabilization of soils with a viscosity higher than 900 cP, which is obtained by adding a water-soluble polymer and a stabilizing foam to each content of hydraulic cement mostly liquid, with a hardened content of liquid hardener adjusting its viscosity greater than or equal to 900 cP and mixing those.

Also, the patent application US 2002152933, describes a composition for the treatment and stabilization of soils, its method of preparation and a use of said preparation, wherein the composition comprises a solid in powder form of particle size less than 2mm in base to calcium. The composition further includes a fluid agent that increases particle agglomeration.

On the other hand, patent application CL 2590-2005, describes a process of chemical stabilization of existing soils in the grade or surface of a determined road or terrain which in one of its stages comprises adding to a volume of soil a solid additive. , and perform a pre-mix simultaneously or later with a liquid additive, which is composed of hydrocarbons and sulfates that are previously diluted in water with acidic pH to be applied later. When the mixture of additives and soils is carried out, the latter increases its support capacity and impermeability and thus improves its structural capacity.

The fundamental difference of the cited documents of the prior art, as well as others that can be found in the literature, is given by the fact that the invention reveals a pavement structure composed of two layers, in which, the lower layer has been designed to have optimal conditions of stability, resistance and impermeability, in order to resist the most important demands of the road, with which, the upper layer, It transforms into a low-thickness rolled folder, easily repairable at a low cost, mainly to withstand the demands related to abrasion.

DESCRIPTION OF THE FIGURES Figure 1 . It shows a cut of a prior art pavement structure.

Figure 2. Shows a section of the pavement structure of the invention DETAILED DESCRIPTION OF THE INVENTION With reference to figure 1, in which a pavement structure of the traditional type of the prior art is observed, it is observed that it is composed of a granular base (2) generally prepared by means of a change of graduation of the existing floor, which can be obtain by means of soil mixtures and / or the change of its size of granulation by sieving. This type of granular bases, in general, have a support capacity (CBR) greater than or equal to 80%. In this type of flooring, in order to improve the supporting capacity of the structure as a whole, it is necessary to use a superficial asphalt layer of considerable thickness (l), which in turn, considerably increases the manufacturing costs.

On the other hand, Figure 2 shows the pavement structure of the invention, preferably used on all-purpose roads and streets exposed to high traffic demands and industrial use. It is noted that said structure comprises at least two layers. The first one is the lower layer or base (4), which has a support capacity greater than or equal to 100% (CBR = 100%) and / or a Resistance to Understanding > 20 Kg / cm2, corresponding to a layer formed from the originally existing soil, treated by a physical-chemical stabilization process. This first layer or base, supports virtually all of the stresses to which the road is subjected and to be chemically stabilized, has a thickness less than the equivalent layer in a road of traditional type. The second one is an upper layer (3), corresponding to an asphalt roll, notoriously inferior to the upper asphalt layer of a traditional prior art road, which provides a support capacity for the pavement structure practically nil.

In figure 1, it is clearly observed that the loads or loads of the road are absorbed in a comparable manner by both the upper layer and the lower layer, diametric situation opposite to that observed in Figure 2, in which the upper layer does not absorb load and the stresses are completely assumed by the lower layer.

In the present invention, the first lower layer or base is composed of the soil originally existing in the ground in which the road will be built, a portion of solid additives; and a portion of liquid additives. Said portion of solid additives corresponds to hydroxides, silicates, carbonates, clays and / or chlorides, which are added together or separately to the originally existing soil. Likewise, the portion of liquid additives is composed of hydrocarbons and sulphates diluted in water, which are added to the original existing soil and to said portion of solid additives.

To determine the appropriate volumes and portions of solid and liquid additives, which must be incorporated into the existing soil in the terrain where the road will be built, a physical analysis of it is necessary, which allows establishing the characteristics of size, shape, limits of consistency , density, specific weight and volume of the fine portion of the soil. Likewise, the mineralogical structure of the fine part (under 40 mesh) of the soil is analyzed through X-ray diffraction tests, which determine the electrical constitution of the existing soil and, particularly, the polarity of the fine portion thereof, through the analysis of the minerals that compose it. Then, keeping in mind the objective of achieving high levels of CBR support and compressive strength in the base layer, the quantities and compositions of said additives to be added to the soil are determined. In particular, the solid additive is present in a volume and composition such that it allows the neutralization of the electrical charges of the existing soil and the liquid additive, is added in an amount determined by the granulometry and the maximum dry density of the mixture, which favors the ionization process of fine components.

Considering the structure of the lower or base layer and the support capacity achieved with the incorporation of solid and liquid additives, it is possible to design the road in such a way that the top or asphalt layer is of a minimum thickness to withstand the required stresses to abrasion.

Additionally, the constructive process incorporates a third intermediate layer consisting of a primer or irrigation of the ligament, preferably in an emulsion of the anionic type of slow break diluted in water, which only allows the union between said first lower layer or base and said second upper layer or binder and, usually, it is an asphalt composition highly diluted in a certain solvent.

The design of the pavement structure of the present invention considers that the first lower layer or base has a thickness which is in a range of 150 to 450 mm. On the other hand, the second top layer or asphalt roll has a thickness in the range of 3 to 50 mm.

In some cases, such as when there are significant static load stresses or when the asphalt is scarce or very expensive or for specific industrial uses, the asphalt layer can be replaced by solutions in adocretos, special polyurethane paints or other elements of flexible behavior .

Various experiences developed in the field, have generated preferred embodiments of the present invention, which exemplify embodiments, even when they do not represent limitations for the scope of protection. In this way, the present invention has been experienced where the soil receiving the physical-chemical stabilization treatment for the implementation of the first layer of the pavement structure of the invention, corresponded to the existing soil in the ground (or mixtures of the existing soil). with some other material), having a maximum size of 2", medium plasticity (IP greater than 1% and less than 12%, LL <40%), the intern by mesh No. 200 must be higher than 10% and lower to 22%, and CBR> 20% In floors of these characteristics a pavement structure has been obtained where the base layer has a thickness in the range of 150 to 300 mm and the top layer asphalt, a maximum thickness of 40 mm .

On the other hand, Table 1 below shows the results of the application of the invention in different soils with different support capacity.

Claims (1)

1. CLAIMS A flexible pavement structure of preferential use on all-purpose roads and streets exposed to high traffic loads and, more preferably, on roads and streets of industrial type, CHARACTERIZED because said structure comprises at least two layers; a first lower layer or base that provides essentially all of the support capacity, said support capacity being given by a parameter CBR = 100% and / or Compression Strength > 20 Kg / cm2, where said base corresponds to a layer formed from the originally existing soil, treated by a physical-chemical stabilization process; and a second upper layer, corresponding to a folder of asphalt roll of reduced thickness that provides essentially no support capacity. A pavement structure according to claim 1, CHARACTERIZED because it comprises a third intermediate layer primer or irrigation garter, which allows only the connection between said first lower layer or base and said second upper layer or rolling folder. A pavement structure according to the preceding claims, CHARACTERIZED in that said first lower layer or base is composed of the originally existing floor, plus a portion of solid additives and a portion of liquid additives. A pavement structure according to the preceding claims, optionally CHARACTERIZED, the floor originally existing includes other floors to obtain a mixture that meets a maximum size of 2", medium plasticity (IP greater than 1% and lower than 12%; LL < 40%), and the intern by mesh No. 200, greater than 10% and less than 22%, and CBR> 20% A pavement structure according to claim 3 and 4, CHARACTERIZED in that said portion of solid additives corresponds to hydroxides, silicates, carbonates, clays and / or chlorides, which are added together or separately to the originally existing soil and are present in a volume and composition determined to neutralize the electrical charge of the fine portion of said existing soil. A pavement structure according to claims 3, 4 and 5, CHARACTERIZED in that said portion of liquid additives are composed of hydrocarbons and sulfates diluted in water, which are added to the originally existing soil and said portion of solid additives, and are present in a quantity, generally, constant. A pavement structure according to the preceding claims, CHARACTERIZED in that said first lower layer or base has a thickness in the range of 150-450 mm A pavement structure according to the preceding claims, CHARACTERIZED in that said second top layer or asphalt roll folder has a thickness in the range of 3-50 mm.