JPH0210109B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a concrete pavement structure made of a composite material having both rigidity and flexibility, which is a combination of the flexibility of asphalt and the rigidity of cement. (Prior Art and Problems) Conventionally, pavements made of this type of composite have been used for paving roads, yards, etc., and are commonly called semi-rigid pavements. By the way, conventional semi-rigid pavement generally uses aggregate with a particle size that has a void ratio of 20 to 30% by volume.
So-called heated aggregate heated to 170℃~180℃,
A predetermined amount of asphalt that has been separately heated to 145°C to 160°C and a predetermined amount of filler that is at room temperature are stirred and mixed in a mixer at an asphalt plant to produce what is called open-grain asphalt concrete. First, it is spread on a roadbed to a predetermined thickness and rolled to form a base. Next, cement paste or fly ash-containing cement paste is usually injected into the voids from the surface of the laid base made of open-grained asphalt concrete for paving. In this case, additives such as synthetic rubber latex are generally mixed into the cement paste or cement paste containing fly ash in order to improve its penetration performance and increase its adhesion. In addition, during the pouring process, the cement paste is filled into the voids while applying vibrations using a vibrating roller, and the cement paste is completed through surface shaping and curing. However, in this construction method, the penetration depth of the cement paste must be controlled based on the empty state of the open-grained asphalt concrete that serves as the base and the fluidity of the cement paste. However, the upper limit of the porosity of open-grained asphalt concrete is set at around 35%, considering workability. Therefore, if you want to increase the amount of permeation of cement paste and increase the bearing strength by increasing the void ratio than this, it will be necessary to ensure the flatness of the pavement surface.
Its construction will be extremely difficult. Furthermore, even if the penetration depth is increased without degrading the quality of the cement paste, the maximum thickness of each layer is 7 to 8 cm. In other words, semi-rigid pavement made of open-grained asphalt concrete and infiltrated with cement paste has the disadvantage of having limitations on ensuring the levelness of the pavement surface and on the thickness of the pavement. Moreover, cement paste itself has poor slip resistance, so if you try to improve the slip resistance with fine aggregate, the permeability will be poor, and a layer of paste will remain on the surface, which can cause cracks. There were also some problems. However, this semi-rigid pavement has superior oil resistance, abrasion resistance, and flow resistance compared to asphalt concrete pavement, and does not require the expansion and contraction joints required for cement concrete pavement, resulting in deformation in areas where cement concrete breaks. It has the characteristic of being able to follow the quantity well. Furthermore, this semi-rigid pavement has the advantage of reducing the use of bituminous materials, which are dependent on imported resources, and allowing the use of domestically produced cement. In light of these circumstances, this invention aims to popularize semi-rigid pavement, and while compensating for the drawbacks of semi-rigid pavement, which is constructed using conventional open-grained asphalt concrete as a base, it also provides rigidity and flexure that bring out its strengths. This invention was developed with the aim of providing a cement concrete pavement consisting of a composite material with high properties. (Means for Solving the Problems) As a means for achieving the above object, the present invention uses aggregate having a film of a viscoelastic material made of asphalt or a petroleum resin binder, and a cement mixed fluid that has not yet hardened. It is characterized in that it is kneaded, laid or poured, and solidified and cured to form a cement concrete pavement with a composite structure having rigidity and flexibility. Further, to specifically explain the structure of the present invention, first, the viscoelastic material used in the present invention is one to which asphalt or petroleum resin binder is added. This is added for the purpose of absorbing or diffusing the volume change in the viscoelastic body when the cement mixed solidified product expands or contracts in response to temperature changes and causes a volume change. In this case, whether to use the viscoelastic material by heating it or by coloring it is selected in consideration of the conditions of use as appropriate. Moreover, when coloring, it is preferable to use a petroleum resin binder. This is because the petroleum resin binder has the effect of removing the black color of asphalt, improves the appearance, and has physical properties that match the properties of asphalt. A commercially available product was used as the petroleum resin binder. Crushed stone, gravel, or sand may be used as the aggregate with a viscoelastic coating.For road paving aimed at wear resistance, aggregates with high hardness are used, and when trying to reduce the weight of building walls, etc. It is possible to select lightweight aggregates with less In particular, cutting waste from a bituminous mixture pavement can be easily used because it is an aggregate that already has a bituminous coating as a viscoelastic coating. Cement paste, cement paste with fly ash, or cement concrete is used as the cementing material, and any suitable material can be selected and used. Incidentally, rubber latex can also be used to impart fluidity and adhesive properties to this mixture. In addition, steel fibers and glass fibers can be used to increase the toughness of cement concrete pavement, and synthetic resin fibers such as polyethylene and polypropylene can be used to restrain cracks and absorb shock. It is also easily possible to obtain colorful composite cement concrete pavements by adding various color pigments. Next, when forming a viscoelastic film on the aggregate, the aggregate and the above-mentioned asphalt or petroleum resin binder are heated separately to around 150°C, and appropriate amounts are put into a mixer and stirred and kneaded. When sufficient mixing is achieved, drain and bathe with cooling water. At this time, a large amount of water vapor is generated, but a film of asphalt or petroleum resin binder is formed on the outer surface of the aggregate or asphalt, and the asphalt or petroleum resin binder is cured and there is no binding force between them. Each grain is separated. By mixing the filler prior to this stirring and kneading, the filler bitumen or filler binder increases the film thickness and does not separate into grains and form nodules. The coated aggregate thus produced is in the form of independent particles, has no mutual binding force, and has a property that it can be well kneaded with a cement mixture fluid that has not yet solidified. Various modifications can be made to the method for producing the aggregate having the viscoelastic coating, and the method is not limited to the above method. When coloring, the color effect can be enhanced by using a petroleum resin sizing agent. The viscoelastic material is selectively used in a ratio of 1.5 to 6.24 parts by weight per 100 parts by weight of the aggregate to form a viscoelastic film with cushioning properties on the surface of the aggregate. do. This coated aggregate is stored, preferably out of direct sunlight, and mixed with cement or cement mixture in the required amount. Mixing can be done using a normal cement mixer, and the mixing ratio of coated aggregate and unhardened cement paste/cement mortar or cement concrete is 80 to 35% of the cement mixture fluid.
Although it is selected within the range of volume, it differs depending on the purpose of paving the composite cement-concrete pavement, and in principle, any mixing ratio can be selected to create a composite cement-concrete pavement with desired strength and flexibility. Next, a mixture of the coated aggregate and an unhardened cement fluid mixture is laid or poured to a desired thickness and allowed to solidify and cure. For this leveling and coagulating curing method, conventionally used mechanical equipment and methods may be employed, and there is no particular improvement in the conventional method by using such materials. As a result, it was confirmed that the composite cement-concrete pavement that was completed had similar or even superior effects to semi-rigid pavement constructed using conventional construction methods. By the way, in the conventional semi-rigid pavement method, in order to allow the cement paste to penetrate as far as possible to the lowest layer of open-grained asphalt concrete, a relatively thin layer (3 to 6 cm) of open-grained asphalt concrete is laid. Then, cement paste was poured from the surface and vibrations were applied to fill the voids. Furthermore, in order to increase the required thickness, the above-described construction had to be repeated. However, even with such construction, in order for the cement paste to fill all the voids, it is necessary to strictly control the particle size of the open-grained asphalt concrete, keep the heating temperature within a specified range, and perform uniform paving. Sufficient attention must also be paid to liquidity management. Even if one of these is insufficient, a semi-rigid pavement with cavities is created, which has the drawback of causing emulsification and peeling of the asphalt due to groundwater, etc. Alternatively, since it must be formed in layers to achieve the desired thickness, the strength is expected to be weaker than that of a single plate. The present invention not only does not have the construction disadvantages and post-construction disadvantages of conventional semi-rigid pavements, but also has more flexibility than concrete structures, not only for one pavement but also for asphalt structures. It demonstrated its function as a composite cement-concrete pavement with completely new rigidity and flexibility, making it a third type of structure with greater rigidity. This was proven by the results of the following examples and comparative examples. Below, a comparative test will be conducted on a composite cement concrete pavement with rigidity and flexibility according to the present invention as Example-1, a conventional semi-rigid pavement as Comparative Example-1, and a dense-grained asphalt concrete as Comparative Example-2. We will explain the outline of the process. 1 Test details Marshall stability test (Asphalt pavement essential information appendix 4-9, published August 25, 1976) 2 Materials used 2-1 Examples of straight asphalt penetration of bitumen among viscoelastic materials 60-80 , used in common with comparative examples. 2-2 Crushed hard sandstone is commonly used as coarse aggregate. 2-3 Fine aggregate from Kinugawa is commonly used. 2-4 Portland cement is commonly used as cement. 2-5 Using SBR latex as an additive to cement. 3 Production of coated aggregate Coated aggregate is produced using an asphalt mixer.
Heated aggregate (170℃~180℃) and heated asphalt (140℃~160℃) are applied to the aggregate.
After mixing 1.5% by weight and thoroughly kneading, the aggregate was immersed in water, and the aggregate was coated with an asphalt film, and then stored in a constant temperature and humidity room at a room temperature of 20°C ± 1°C and a humidity of 60 ± 5%. 4 Formulation 4-1 The formulation of Example-1 is shown in Table-1.

[Table] 4-2 The formulation of Comparative Example-1 is shown in Table-2 and Table-3.

【table】

【table】

【table】 4-3 The formulation of Comparative Example-2 is shown in Table-4.

[Table] (Note) Crushed stone and screenings are from Tochigi.
Produced in Sano City, Prefecture 5 Mixing, method of preparing specimen and curing 5-1 In Example-1, coated aggregate, cement, water, fine aggregate, and rubber latex were simultaneously charged into a mortar mixer and mixed for about 1 minute. The material was then compacted in a mold and cured in water (20±3°C) until 7 days old. 5-2 In Comparative Example-1, open-grained asphalt concrete based on the formulation shown in Table-2 was poured into a marshall test mold using the above-mentioned asphalt pavement essential network marshal stability test method, and the asphalt concrete was After the temperature had cooled to room temperature, a paste with the composition shown in Table 3 was injected from the surface, and the missing paste was replenished while vibrating using a table vibrator, and the material was cured in water until it was 7 days old. The filling amount of the paste was adjusted to 25% by volume. 5-3 In Comparative Example-2, a specimen was prepared as usual and cured in air. 6 Test Results 6-1 The results of the Marshall stability test are shown in Table-5.

[Table] 6-2 Summary of Results 6-2-1 Comparative Example-1 and Comparative Example-2 have almost the same flow value, but the stability is approximately 60% higher in Comparative Example-1. 6-2-2 Regarding the three types of Example 1, as the amount of mortar increases, the flow value and stability also increase. 6-2-3 There is a significant difference in flow value between Example-1 and Comparative Example-1. 7 Discussion 7-1 Comparing the paste amount of 25% in Comparative Example-1 and the mortar amount of 35% in Example-1, the cement mixture is increased by 40% (35/25 = 1.4) even though it is the same semi-rigid body. The flow value remains unchanged. This seems to be because the construction method according to the present invention, unlike the conventional construction method, has the effect of increasing the rigidity of semi-rigid pavement, that is, the contact between the aggregates has changed from surface contact to point contact. 7-2 Example-1 is not a construction method in which open-grained asphalt concrete is laid, compacted, and then cement paste is poured into the voids as in Comparative Example-1, so it was not possible to form layers to form the desired thickness. , construction efficiency is extremely high because it can be immediately constructed to any thickness dimension. Particularly when semi-rigid materials are used at an early stage, construction can be completed in a short time because there is no temperature drop as with open-grained asphalt concrete. 7-3 In Example-1, since the amount of mixed cement fluid that has not yet hardened can be freely adjusted, a composite cement-concrete pavement that meets the desired strength can be easily obtained. 7-4 Since Example-1 can use cement mortar and cement concrete, it is free from the risk of shrinkage cracks caused by paste, and when used for pavement, it can increase the slip resistance of running wheels. Although this test gave an overview of the composite cement concrete pavement having rigidity and flexibility according to the present invention, the destructive test of the composite cement concrete pavement will be explained in more detail. Therefore, as Example-2, when coated aggregate according to the present invention was used, the amount of mortar mixed was changed to 80%, 60%, 50%, and 40%, and asphalt concrete pavement was used as coated aggregate. A total of 6 types were used: one using cutting waste generated during repair work with 50% mortar mixed in, one using coated aggregate and steel fiber with 60% mortar mixed in, and Comparative Example 3 with 100% mortar. about,
A destructive test was conducted. 1 Test contents Compression test JISA-1108 and bending test JISA-1106
shall be. 2 Materials Used 2-1 For those common to Example-1, equivalent materials were used. 2-2 The particle size of cutting waste and amount of asphalt are as shown in Table-6. 2-3 Steel fiber is used as fiber, shape is 0.5
×0.5×30mm, specific gravity 8.0 3 The composition of coated aggregate is as shown in Table 7.

【table】

【table】

[Table] 4 Preparation of specimen First, coated aggregate was manufactured, and a cylindrical frame with a diameter of 10 cm and a height of 20 cm was used as a compression test specimen, and a water-cement ratio of 50 was used as a cement mixture that had not set yet.
% and was prepared according to the predetermined amount of mortar mixed in. As the specimen for the bending test, a mold body with a width of 10 cm, a height of 10 cm, and a length of 40 cm was used. Test specimens using cutting waste also had a water-cement ratio of 50.
A test piece was prepared in the same manner with the amount of mortar mixed in as 50%. When mixing steel fiber, reduce the amount of mortar mixed in.
A test piece was prepared in the same manner by weighing the sample so that the volume ratio was 1.5% with respect to the volume of the sample, and adding it to the mixture while massaging it by hand. Note that the curing method and other repeating methods were followed as in Example-1. 5 Test items and methods 5-1 Test items and measuring equipment are as shown in Table 8, and the test method is JISA 1108, JISA
I followed 1106.

[Table] 6 Test results Table 9 shows the test results and the amount of distortion from the measured values.

[Table] 5-2 Summary of results From the test results on the 28th of the Materials Ordinance, the following general trends can be pointed out. 5-2-1 Regarding compressive strength, it correlates well with the amount of mortar mixed in, regardless of the presence of steel fibers or cutting waste. That is, as the amount of mortar mixed in decreases, the compressive strength decreases. 5-2-2 The bending strength is about 40% higher when steel fiber is mixed than when using coated aggregate with the same amount of mortar (70.6÷50.3=
1.4), and when cutting waste is used, it is 60% of the same amount of mortar when using coated aggregate (31.7÷49.9=0.6). When using coated aggregate, the amount of mortar does not matter. 5-2-3 Bending strain shows a significantly high value when steel fiber is mixed, followed by a value that is 10% larger when using cutting waste compared to when using the same amount of mortar (626÷574=
1.1). When using coated aggregate and changing the amount of mortar, there is a good correlation in inverse proportion. As the amount of mortar decreases, bending strain increases. 5-2-4 Bending strain at 80% mortar content
It is 365×10 ^-6 and 470×10 ^-6 at 60%, which is a very large value compared to 100×10 ^-6 for normal cement concrete. 5-2-5 In Table 9, the compressive flexural strength ratio value, which is the compressive strength divided by the flexural strength, indicates the toughness of the concrete. For example, in the case of Comparative Example 3, the compressive strength is 2.33 and the bending strength is 39.6, so the toughness is 5.88, and similarly, Example 2-1 shows a remarkable difference of 4.0. In Example 2-5, 2.0 is shown,
The composite cement concrete according to the present invention exhibits toughness in the range of toughness 2-4. 6 Idea 6-1-1 If we consider the cement concrete slab in the form of linear expansion, it is expressed as ε ₁ = α・θ. ε ₁ : Line strain α: Expansion coefficient of concrete (℃)・10×10 ^-6
shall be. θ: Temperature difference of concrete, 30℃. ε ₁ = 30×10×10 ^-6 = 300×10 ^-6 . 6-1-2 It is reasonable to consider that the drying shrinkage of concrete is generally 200×10 ^-6 .
(Concrete Standard Specification Explanation/Japan Society of Civil Engineers) 6-1-3 Initial curing shrinkage strain is 100×10 ^-6
However, in this composite concrete, if the aggregate gap is 10 mm, the viscoelastic body
It will be pulled by a length of 1μ. This viscoelastic body exhibits liquid-like physical properties at such shrinkage rates, and the filler bitumen (mixture of filler and asphalt) corresponds well. 6-1-4 Concrete plate is ε ₁ = 300×
10 ^-6 , so the allowable strain of concrete
Much higher than 150-200×10 ^-6 . For this reason, contraction joints and expansion joints are required for cement concrete slabs, and in the cement concrete pavement network, the standard value for the horizontal expansion joint spacing is 80 to 240 m when the construction period is from April to November, and 12 In the case of March to March, 40 to 80 m is shown, and the standard horizontal contraction joint spacing is 7.5 m, 8 m, and 10 m. However, since the strain of the composite cement-concrete pavement according to the present invention is 360 times 10 ^-6 or more, joints are not required if this is applied to pavements and other structures constructed with conventional concrete. 6-2-1 Paving using the composite cement-concrete pavement according to the present invention not only reduces the joint construction cost, which accounts for about 25% of the cost in pavement construction, but also reduces erosion of the roadbed and unevenness due to rainwater flowing in from the joints. It is possible to completely eliminate the occurrence of bumps, etc., ensure the safety of the traveling vehicle, and eliminate the discomfort caused to the driver from bump shocks. 6-2-2 When constructing walls using cast-in-place concrete during construction work,
Cracks are likely to occur in the window frame. This is thought to be caused by drying shrinkage and expansion/shrinkage due to temperature changes. That is 6
-As explained in 1-4, a strain of 300 x 10 ^-6 occurs in the vertical and horizontal directions in concrete that only has a strain ^of 150 to 200 x 10 -6. This is the combined amount of strain, so it is easy to crack. This is why this occurs. If the composite cement concrete according to the present invention is used in such places, cracks will not occur on the wall surface. Although the properties of the composite cement concrete pavement according to the present invention have been described through the above tests, a wheel tracking test was conducted as Example 3 as a necessary test when used as a pavement material. 1 Test details Wheel tracking test (Asphalt Pavement Guide Appendix 4-12) 2 Materials used For those in common with Examples 1 and 2, equivalent products were used. 3 Test load Comparative example 4 was tested using dense-grained asphalt concrete, and a ground pressure of 6.4 Kg/cm ³ was adopted for heavy traffic use. In Example 3, 11.5 Kg/cm ³ was adopted assuming the harshest conditions, which are around toll collection stations on toll roads. 4 Test results The test results are shown in Table-10.

[Table] 5 Idea Looking at the dynamic stability, Comparative Example-4 was 6.4.
If a ground pressure of Kg/ ^cm3 is applied, it will sink by 1mm.
Although it shows 600 times, it becomes impossible to measure if the same ground pressure of 11.5 kg/cm ³ as in Example-3 is applied. However, in Example 3, when the ground pressure was increased to 11.5 Kg/cm ³ and the dynamic stability was tested at 63,000 times/mm, it becomes clear how large the difference is. Furthermore, since this is a case where the amount of mortar is 25%, it is clear that the use of the composite cement-concrete pavement according to the present invention as a countermeasure against rutting on asphalt-paved roads produces a favorable effect. The viscoelastic coating material for the composite cement concrete pavement according to the present invention has been explained above based on the case where asphalt and a petroleum resin binder are used, but the invention is not limited to these, and a mixture containing a filler may also be used. It is also possible to use a viscoelastic material as long as it has stress relaxation ability. Moreover, crushed stone, gravel, sand pumice, slag, cutting waste, crushed waste, etc. can be used as the raw aggregate of the coated aggregate. Although this has been partially demonstrated in the Examples, the scope of its use is not limited to the Examples. Coloring with pigments, which is a routine practice for those skilled in the art of cement, can also be utilized to a great extent. The composite cement-concrete paving material with rigidity and flexibility according to the present invention can be used not only for road construction and construction work as explained above, but also for pools, retaining walls, etc., free from defects caused by joint structure, and flexible. The object of the present invention is to provide a completely new pavement structure having both high and rigid properties.

Claims (1)

[Scope of Claims] 1. Aggregate having a viscoelastic material coating on the surface of which an asphalt or petroleum resin-based viscoelastic material is applied;
A structure of a composite cement-concrete pavement characterized by being kneaded with a cement fluid mixture and laid on a roadbed. 2 The viscoelastic material is 1.5 parts by weight per 100 parts by weight of aggregate.
2. The composite cement-concrete pavement structure according to claim 1, wherein the surface of the aggregate is coated with the aggregate in a proportion of 6.24 parts by weight. 3 The ratio of the aggregate having the viscoelastic material coating to the cement mixed fluid is such that the volume ratio of the aggregate having the viscoelastic material coating is 20 to 65, and the volume ratio of the cement mixed fluid is 80 to 35. The composite cement concrete pavement structure according to claim 1, characterized in that: 4. The composite cement concrete pavement structure according to claim 1, wherein the composite cement concrete pavement has a bending strain amount of 360×10 ^-6 or more.