CN107476162B

CN107476162B - Ultra-low modulus cement concrete pavement for highway and construction process thereof

Info

Publication number: CN107476162B
Application number: CN201710358332.0A
Authority: CN
Inventors: 李来宾
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-05-19
Filing date: 2017-05-19
Publication date: 2021-02-23
Anticipated expiration: 2037-05-19
Also published as: CN107476162A

Abstract

The invention provides a highway ultralow-modulus cement concrete pavement and a construction process thereof, belonging to the field of highway construction, wherein the adopted technical scheme is that the highway ultralow-modulus cement concrete pavement comprises the following components in parts by weight in a mixture: 60-80 parts of stone, 12-20 parts of cement, 5-10 parts of waste rubber powder and 2-6 parts of modified asphalt emulsion. By adopting stone and cement as main materials and matching with the waste rubber powder and the modified asphalt emulsion, the compression elastic modulus of the cement pavement is effectively reduced, the cement concrete pavement is rigid and flexible, no shrinkage or expansion joint is left, the cement concrete pavement is not softened or deformed in an extremely high-temperature environment, is not brittle or cracked at negative temperature, is strong in water resistance and does not move, and the driving comfort is high; the waste is utilized, the ecological environment is protected, the engineering cost is greatly reduced, and the economic benefit is high; the construction process is simple, the construction cost is low, the process is quick, and the method is suitable for large-scale popularization and application.

Description

Ultra-low modulus cement concrete pavement for highway and construction process thereof

Technical Field

The invention relates to the field of highway construction, in particular to a highway ultralow-modulus cement concrete pavement and a construction process thereof.

Background

Along with the rapid development of social economy, a highway as one of infrastructure is also rapidly developed, along with the increasing requirements of people on highways with high quality and high service performance, the requirements on safety and comfort of driving are also increased, at present, asphalt pavements are mostly adopted as main structural types of high-grade highway pavements in China, however, the pavement construction cost is high, the vehicle speed is limited to be increased due to poor hardness, and bad smell is easily generated under high-temperature sunlight, so that the construction cost is high and the experience feeling is poor. As a more classical cement concrete road surface is once widely used in China, and a part of provincial and urban expressway road surfaces also adopt cement concrete road surfaces, the cement concrete road surfaces are gradually eliminated in the construction of high-grade highways due to the defects of high rigidity, high hardness, high driving noise, poor driving comfort, serious broken plates, difficult maintenance, high maintenance cost and the like, but the cement concrete road surfaces have good water bubble resistance, are stable at high temperature, have small volatilization amount of harmful substances under the direct irradiation of high-temperature sun, have relatively small air pollution, low construction cost, good durability of materials and the like, are deeply favored by professionals, and the excellent essential attributes and social requirements promote the further research and development of high-quality cement concrete road surfaces and have great significance for constructing economic and environment-friendly high-grade highways.

Disclosure of Invention

The invention provides a highway ultra-low modulus cement concrete pavement and a construction process thereof, aiming at solving the technical problems of high rigidity, easy breaking plates, water damage, high hardness, high driving noise and poor driving comfort of the cement concrete pavement.

The invention adopts the technical scheme that:

the mixture of the cement concrete pavement comprises the following components in parts by weight: 60-80 parts of stone, 12-20 parts of cement, 5-10 parts of waste rubber powder and 2-6 parts of modified asphalt emulsion.

Preferably, the mixture of the cement concrete pavement also comprises 0.3-6 parts by mass of waste plastic emulsion or acrylic acid and 0.1-0.3 part by mass of inorganic fiber, wherein the solid content in the waste plastic emulsion is not lower than 45 wt.%.

Preferably, the waste rubber powder is redispersible water-based rubber powder which is subjected to surface activation, softening and emulsification sequentially.

Preferably, the modified asphalt emulsion has a solid content of not less than 45 wt.%.

Preferably, the inorganic fibers are chopped steel fibers, glass fibers or basalt fibers, and the glass fibers or the basalt fibers have an alkaline interface.

The compression elastic modulus of the cement concrete pavement is 1000 Mpa-2500 Mpa.

The invention also provides a construction process of the ultra-low modulus cement concrete pavement of the highway, which comprises the following steps:

(1) preparing materials according to the following parts by mass: 60-80 parts of stone, 12-20 parts of cement, 5-10 parts of waste rubber powder and 2-6 parts of modified asphalt emulsion;

(2) construction: and (3) uniformly mixing the prepared materials in the step (1), paving by using a paver, compacting by using a road roller, and maintaining for more than 7 days.

Preferably, the raw materials also comprise 0.3-6 parts by mass of waste plastic emulsion or acrylic acid and 0.1-0.3 part by mass of inorganic fiber, and the solid content in the waste plastic emulsion and the modified asphalt emulsion is not lower than 45 wt.%.

Preferably, the mass ratio of each component during stock preparation is controlled according to the following principle: firstly, determining the controlled compression elastic modulus of a cement concrete pavement to be constructed according to the deformation of a roadbed, and controlling the compression elastic modulus of the cement concrete pavement to be 1500-2500MPa when the designed roadbed deflection value is less than 100 (0.01 mm); when the roadbed deflection value is 100-; and then carrying out laboratory mix proportion trial preparation, wherein the mix proportion trial preparation method comprises the steps of uniformly mixing the prepared materials, forming by adopting a heavy compaction instrument, preserving for seven days, measuring the actual compression elastic modulus, controlling the compression elastic modulus according to the actual compression elastic modulus, increasing or decreasing the amount of the waste rubber powder by 5-15%, and carrying out mix proportion trial preparation again until the actual compression elastic modulus is within the range of controlling the compression elastic modulus, wherein the proportion of the prepared materials is the proportion of the prepared materials during construction.

Preferably, the waste rubber powder is subjected to surface activation, softening and emulsification treatment sequentially during material preparation in the step (1) to obtain the redispersible water-based rubber powder.

In the technical scheme, measures and approaches for reducing the brittleness, hardness and rigidity of the pavement by reducing the compression elastic modulus of the pavement material are firstly provided. In the pavement materials, the stone is a framework material of the pavement, is a main stressed material in a compact structure and plays a supporting role in the structure; the waste rubber powder replaces sand in the conventional common cement concrete, fills gaps among the broken stones, and the surface adhesive property of the waste rubber powder is adhered to stone and cured cement stone, so that broken stone particles in the structure are in flexible and elastic contact, the compression elastic modulus of the cement concrete is reduced, and the elasticity of a pavement is improved; the modified asphalt emulsion is aqueous emulsion, the solid content in the emulsion is generally not lower than 45wt.%, and the mixture is aqueous material, so the mixture can be easily and uniformly mixed during mixing. Water in the modified asphalt emulsion is utilized to hydrate cement, the cement absorbs the water after the emulsion is broken in the mixture, the asphalt and rubber powder particles are reduced to be in an oily state, and the formed pavement has oiliness and does not absorb water; meanwhile, the adhesion strength of asphalt is utilized to form adhesion strength on material particles, and the adhesion strength and the cement colloid in the structure form two kinds of adhesive materials which are coordinated and matched, so that the strength of the pavement is adjusted, and the modulus of the mixture is further reduced. By adjusting the blending of the components and cooperating with each other in a scientific proportion, the rigidity, brittleness and hardness of the pavement are reduced, the compression elastic modulus of the cement pavement is reduced, and a rigid and flexible tough pavement which is neither hard nor brittle nor soft is formed, so that the cement pavement is a new product with remarkable social and economic values and benefits.

In the construction process, besides the advantages of scientific matching of the raw materials, the cement concrete is paved by a paver in the asphalt pavement process for the first time so as to form the non-kerf pavement.

The invention has the beneficial effects that: (1) the compression elastic modulus of the ultra-low modulus cement concrete pavement of the highway provided by the invention is greatly lower than that of the conventional common cement concrete pavement and is also greatly higher than that of an asphalt pavement, the ultra-low modulus cement concrete pavement of the highway is lower in rigidity than the common cement concrete pavement and harder than the asphalt pavement, and the ultra-low modulus cement concrete pavement of the highway is a novel toughness pavement which is neither hard and brittle nor soft and is both hard and soft; (2) the pavement does not have shrinkage or expansion joints, does not soften or deform under an extremely high-temperature environment, is not brittle or cracked under a negative temperature, has strong water resistance, is not pushed, and has high driving comfort; (3) the raw materials are made of a large amount of waste rubber, plastic and other materials, so that the waste is utilized, the ecological environment is protected, the engineering cost is greatly reduced, and the economic benefit is high; (4) in the improved technical scheme, the waste plastic emulsion or acrylic acid is added to further reduce the modulus of the cement concrete pavement and improve the toughness of the cement concrete pavement, and the chopped fiber is added to be matched with stone and cement to enhance the crack resistance of the cement concrete pavement; (5) the construction process provided by the invention is simple, the construction cost is low, the process is quick, the method is suitable for large-scale popularization and application, and the economic benefit and the social benefit are obvious.

Detailed Description

The following detailed description of the ultra-low modulus cement concrete pavement for road and the construction process thereof according to the present invention is provided by way of specific examples to facilitate understanding, but the present invention is not limited in any way, and the raw materials and construction equipment used in the examples are commercially available without specific reference.

Example 1

In this embodiment, the mixing ratio of the ultra-low modulus cement concrete pavement mixture and the construction method thereof are described by taking the construction of a section of highway as an example.

First, a site survey is conducted. The roadbed of the highway at the construction section has better treatment effect, better overall strength, more uniform and smaller deflection value control, the designed deflection value of the roadbed is less than 100 (0.01 mm), and the compression-resistant elastic modulus of the cement concrete pavement to be constructed is determined to be controlled between 1500MPa and 2500 MPa.

Secondly, preparing materials: according to the construction amount, purchasing cement, broken stone, waste rubber powder, modified asphalt emulsion, waste plastic emulsion or acrylic acid and inorganic fiber, wherein the quality standard of the cement, broken stone, waste rubber powder, modified asphalt emulsion and waste plastic emulsion meet the national standard or standard requirement.

Wherein, the particle size of the crushed stone is controlled to be 10-20mm, and the crushed stone with the particle size is used as a framework material, so that the supporting effect is good, and the hardness property is more excellent; the waste rubber powder has the granularity of 60-150 meshes preferably, and on the performance requirement, rubber powder emulsion or paste which is subjected to surface activation and softening and then emulsification is preferably used, the rubber powder emulsion can be obtained by purchase or can be customized by manufacturers, the waste rubber powder emulsion is treated by using a common environment-friendly activating agent, a softening agent and an emulsifying agent, and the used rubber powder emulsion is water-based and can enable the waste rubber powder to be mixed and dissolved in water so as to be well combined with other water-based materials, such as modified emulsified asphalt and cement concrete. The selection of the emulsified modified asphalt follows the following two points: firstly, determining according to extreme high and low air temperature values appearing in 50 years of a construction project site, selecting modified asphalt with a brittle point lower than the lowest temperature of the project site, controlling the technical index of the emulsified modified asphalt at negative temperature, and ensuring that the asphalt in a pavement slab body is still a soft film at the negative temperature, thereby ensuring the soft connection among structural material particles, resisting the brittleness of a cement concrete pavement at the negative temperature, and ensuring that the pavement still can keep the elastic toughness at low modulus at the negative temperature and is not brittle and not hard; and secondly, controlling the amount of the emulsified modified asphalt by calculating according to the cement amount in the pavement mixture, and controlling the total water content in the emulsion to be equal to the total water demand in the cement hydration process by combining other selected materials such as waste plastic emulsion according to the cement amount in the pavement mixture so that the formed structure does not generate bubbles and water, wherein the solid content in the selected emulsified modified asphalt is generally controlled to be not less than 45% (recorded as the concentration of 45 wt.%). The waste plastic emulsion is obtained by crushing and dispersing waste plastic bags and plastic cloth to form uniform dispersion liquid, adding an emulsifier, stirring and dispersing uniformly to form water-based plastic emulsion, wherein the emulsifier can adopt a conventional emulsifier, preferably adopts the same emulsifier as that in emulsified modified asphalt, and is mixed with cement, water in the emulsifier participates in hydration and solidification of the cement, solid components in the emulsion are reacted and bonded with the cement into a whole by virtue of surface active groups, the inviscibility of the plastic at normal temperature in conventional use is broken, the performance of cement concrete is reduced by independent particles in the cement, and the plastic components in the waste plastic emulsion and the cement form a uniform and integrated structure, so that the elastic modulus of a mixture is reduced, the shear resistance is enhanced, and the defects of pavement cracking and the like are effectively prevented. The inorganic fiber is preferably 2-5cm chopped steel fiber, glass fiber or basalt fiber, more preferably glass fiber or basalt fiber with an alkaline interface formed by surface treatment, and can be obtained by purchasing, and the addition of the chopped steel fiber, the glass fiber or the basalt fiber can effectively improve the compressive strength of the pavement mixture and also has the performances of cracking resistance, freezing resistance and impermeability.

Specifically, in this embodiment, 260kg of 425-labeled cement is prepared for each low-modulus cement concrete pavement mixture, 160kg of crushed stone and 80-mesh waste rubber powder are planted in a manner of 1m, and 110 kg of 50wt.% emulsified modified asphalt with a brittle point of-30 ℃ or lower is planted in a manner of 110-130kg (in this embodiment, extreme high and low air temperature values occurring in 50 years are 35 ℃ and-25 ℃, respectively, and 55-65kg of water is required for cement hydration).

Thirdly, carrying out laboratory mix proportion trial assembly on the prepared materials in the second step, specifically, molding by adopting a heavy compaction instrument after uniformly mixing, maintaining for seven days, measuring the actual compression elastic modulus of the trial assembly sample mixture, comparing the actual compression elastic modulus with the control compression elastic modulus determined in the first step, if the actual compression elastic modulus is less than 1500Mpa, reducing the addition of the waste rubber powder by 8 percent, and carrying out laboratory mix proportion trial assembly again until the actual compression elastic modulus is in the range of 1500-2500 Mpa; if the actual compression elastic modulus is larger than 2500Mpa, increasing 8% of the addition of the waste rubber powder, carrying out laboratory mix proportion trial run again until the actual compression elastic modulus is in the range of 180-240Mpa, finding out the optimal mix proportion through tests, and fixing the use amounts of various materials as follows: 260kg of No. 425 cement, 1m of 10-20mm crushed stone, 160kg of waste rubber powder and 120kg of 50wt.% emulsified modified asphalt.

And fourthly, on-site construction, inputting the use amounts of various materials determined according to the tests into a computer, mixing by an automatic control mixing plant, specifically adopting an asphalt mixing plant or a water-stable macadam continuous mixing station, further transporting by a dump truck, paving by a paver, compacting by a road roller, and finally curing for more than 7 days, thereby forming the ultra-low modulus cement concrete pavement.

Example 2

The cement concrete pavement of the invention is found to have excellent properties through the trial preparation of a plurality of laboratory mix proportions, and the mix proportions are exemplarily listed in the following table 1.

TABLE 1 ultra-low modulus cement concrete pavement mixture composition and proportioning example

The mixture of the cement concrete pavement comprises the following components in parts by weight: 60-80 parts of stone, 12-20 parts of cement, 5-10 parts of waste rubber powder, 2-6 parts of modified asphalt emulsion, 0.3-6 parts of waste plastic emulsion and/or acrylic acid and 0.1-0.3 part of inorganic fiber, wherein in the proportion, 70-80 parts of stone, 12-15 parts of cement, 4-6 parts of modified asphalt emulsion and 3-4 parts of waste plastic emulsion and/or acrylic acid are preferred. The elastic modulus of the road pavement can be adjusted within a certain range by adjusting the proportion of each component, the proportion is widely suitable for roads in various places, the road pavement can generally meet bearing work, does not crack or deform, is not easy to rut, is comfortable to form, and can be popularized in a large range.

At present, common cement concrete pavements take cement, broken stones and sand as main materials, the elasticity modulus of the common cement concrete pavements is generally more than 30000, the common cement concrete pavements have high hardness but also high brittleness and are easy to crack; the elastic modulus of the asphalt mixture is generally 300-600, and the road surface is soft due to the excessively low elastic modulus, so that rutting is easy to occur, and the driving speed is influenced. The mixture formed by the mixing proportion controls the elastic modulus of the cement concrete pavement between 1000Mpa and 2500Mpa, compared with the common cement concrete pavement, the elastic modulus is greatly reduced by about 90 percent, and simultaneously, the compressive strength is greatly higher than that of an asphalt pavement, so that the flexibility degree of the pavement can meet the working requirement of a roadbed forever, the lower bearing layer can work, the slab cannot be broken, and the structure safety is ensured. The mixing proportion contains a large amount of fibers, so that the road surface is further ensured not to be brittle at negative temperature, large cracks are not generated, the base layer is prevented from being damaged by water leakage, and the integrity and the performance of the road surface are ensured to be well maintained.

The road surface batch mixture of the invention adopts skillfully selected materials and scientifically proportioned dosage, and the test of the compression elastic modulus test method and the instrument of the asphalt mixture shows that the invention firstly reduces the compression elastic modulus of the cement concrete road surface to below 2500Mpa, meanwhile, the compressive strength of the pavement is ensured, the layer bottom of the pavement can not generate tensile stress, the pavement thickness required by meeting performance requirements is reduced, the thickness is generally enough to 12-15 cm, the material consumption is greatly reduced, the pavement integrates the advantages of a cement concrete pavement and an asphalt pavement, overcomes the defects of the two pavements, maintains the excellent properties of the cement concrete pavement, effectively solves the defects of high rigidity, high hardness and high driving noise of a common cement concrete pavement, meanwhile, the asphalt pavement has the comfort level for running vehicles, the structure is safe and guaranteed, and the asphalt pavement is a brand-new pavement structure layer! It is worth pointing out that the raw material source in the road surface is wide, the cost is low, the engineering construction cost is greatly reduced, and the quality guarantees the quality of the cement concrete road surface. The cost is low, and huge economic benefits and social benefits are certainly generated.

Claims

1. The ultra-low modulus cement concrete pavement for the highway is characterized in that a mixture of the cement concrete pavement is composed of the following components in parts by weight: 60-80 parts of stone, 12-20 parts of cement, 5-10 parts of waste rubber powder, 2-6 parts of modified asphalt emulsion, 0.3-6 parts of waste plastic emulsion and 0.1-0.3 part of inorganic fiber; the solid content in the waste plastic emulsion is not lower than 45 wt.%; the compression elastic modulus of the cement concrete pavement is 1000-2500 Mpa; the waste rubber powder is redispersible water-based rubber powder which is subjected to surface activation, softening and emulsification sequentially, and the granularity of the waste rubber powder is 60-150 meshes.

2. The ultra-low modulus cement concrete pavement for roads of claim 1, wherein the modified asphalt emulsion has a solids content of no less than 45 wt.%.

3. The ultra-low modulus cement concrete pavement for a road of claim 1, wherein said inorganic fibers are chopped steel fibers, glass fibers or basalt fibers, said glass fibers or basalt fibers having an alkaline interface.

4. A construction process for a highway ultralow-modulus cement concrete pavement is characterized by comprising the following steps:

(1) preparing materials according to the following parts by mass: 60-80 parts of stone, 12-20 parts of cement, 5-10 parts of waste rubber powder, 2-6 parts of modified asphalt emulsion, 0.3-6 parts of waste plastic emulsion and 0.1-0.3 part of inorganic fiber, wherein the solid content of the waste plastic emulsion and the modified asphalt emulsion is not lower than 45wt.%, the waste rubber powder is subjected to surface activation, softening and emulsification treatment in sequence to obtain redispersible water-based rubber powder, and the granularity of the waste rubber powder is 60-150 meshes;

(2) construction: uniformly mixing the prepared materials in the step (1), paving by using a paver, compacting by using a road roller, and maintaining for more than 7 days; the mass ratio of each component is controlled according to the following principle during material preparation: firstly, determining the controlled compression elastic modulus of a cement concrete pavement to be constructed according to the deformation of a roadbed, and controlling the compression elastic modulus of the cement concrete pavement to be 1500-2500MPa when the designed roadbed deflection value is less than 100 (0.01 mm); when the roadbed deflection value is 100-; and then carrying out laboratory mix proportion trial preparation, wherein the mix proportion trial preparation method comprises the steps of uniformly mixing the prepared materials, forming by adopting a heavy compaction instrument, preserving for seven days, measuring the actual compression elastic modulus, controlling the compression elastic modulus according to the actual compression elastic modulus, increasing or decreasing the amount of the waste rubber powder by 5-15%, and carrying out mix proportion trial preparation again until the actual compression elastic modulus is within the range of controlling the compression elastic modulus, wherein the proportion of the prepared materials is the proportion of the prepared materials during construction.