JPS6251323B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a semi-rigid pavement construction method, and more particularly to a cement paste or mortar (hereinafter referred to as cement milk) composition used in the construction method. Conventionally, there have been two major systems of pavement: asphalt pavement and concrete pavement, but recently semi-rigid pavement that combines the characteristics of both has been proposed and put into practice. Semi-rigid pavement is generally made by first applying an open-grained asphalt concrete layer with a porosity of 20-30%, which is made by mixing open-grained aggregate and asphalt in an amount of 3-5% by weight (relative to aggregate), on the pavement base. After pouring the
After spreading cement milk containing rubber latex from the open-grained asphalt concrete and injecting the cement milk into the voids of the asphalt concrete using a vibrating roller, the cement milk remaining on the surface is scraped off using a rubber rake or the like. A semi-rigid pavement was obtained by solidifying the cement milk. Therefore, the cement milk used in this construction method is required to have the following properties. (1) It must have appropriate consistency. (2) There shall be no minute cracks on the surface of the completed semi-rigid pavement. The above consistency requirement is a condition for smooth injection and penetration of cement milk into open-grained asphalt concrete. Cement milk having a consistency of 9 to 20 (preferably 9 to 12) is suitable. Furthermore, the requirement to prevent the occurrence of cracks is a natural requirement for maintaining the performance of the paving slab, but with mere cement milk, cracks are unavoidable as long as the consistency requirements are satisfied. satisfy consistency requirements and
In order to satisfy the crack prevention requirements, it is necessary to incorporate more than a certain amount of rubber latex into the cement milk. Based on our extensive experience in construction, the amount of rubber latex to be blended to satisfy the requirements for preventing crack generation is 3.7 to 3.8% by weight based on the cement weight in terms of solid content of rubber latex. However, rubber latex is extremely expensive compared to other materials used in semi-rigid pavement, such as cement, aggregate, asphalt, etc., and there is a limit to reducing its compounding amount as mentioned above. The construction costs are increasing, which is hindering its widespread use. An object of the present invention is to provide a method for reducing the amount of rubber latex required to be blended into cement milk used in semi-rigid pavement construction methods, that is, to provide a cement milk composition for semi-rigid pavement construction methods that contains a small amount of rubber latex. . As a result of intensive research to achieve the above object, the present inventors found that by mixing a specific cement admixture into cement milk, cracks do not occur on the pavement surface even if the amount of rubber latex mixed is significantly reduced. They discovered this and completed the present invention. The present invention is a semi-rigid pavement method in which a pavement slab is formed by injecting and penetrating cement paste or mortar after pouring an open asphalt concrete layer with a porosity of 20 to 30% on a base. 1.5 to 2.5% by weight based on cement weight (b) One or two selected from the group consisting of formaldehyde condensates of aromatic hydrocarbon sulfonic acids, formaldehyde condensates of sulfonic group-containing aminotriazine, and lignin sulfonates. This is a semi-rigid pavement construction method characterized by using cement milk which contains 0.2 to 0.4% by weight of the above based on the cement weight and whose consistency is such that the pouring time through the P funnel is 9 to 20 seconds. In the present invention, the rubber latex includes natural rubber or synthetic rubber such as polybutadiene, butadiene-styrene copolymer, polystyrene, butadiene-acrylic copolymer, polyisobutylene,
Polychloroprene, isobutylene/isoprene copolymer, ethylene/propylene copolymer, etc. are emulsified and dispersed in water, and these rubber latexes can be used alone or in combination. good. In particular, styrene-butadiene copolymer is preferably used. Among the additives used in the present invention, formaldehyde condensates of aromatic hydrocarbon sulfonic acids are benzene substituted or unsubstituted with alkyl groups,
These are products obtained by condensation reaction of the same or different sulfonated aromatic hydrocarbons such as naphthalene and anthracene with formaldehyde, and their salts, and sodium salts or calcium salts of formaldehyde high condensates of naphthalene sulfonic acid are preferably used. be done. The formaldehyde condensate of aminotriazine containing a sulfonic group was
- at least 2 as described in Publication No. 21659
It is a product obtained by condensing formaldehyde with a substrate in which a sulfonic acid group has been introduced into an amino-S-triazine having 2 amino groups, and a specific example is a formaldehyde condensate of melamine sulfonic acid. Furthermore, lignin sulfonate is manufactured industrially using sulfite pulp waste liquid as a raw material, and is well known as a cement dispersant. Various methods have been proposed for producing lignin sulfonate for cement dispersants using sulfite pulp waste liquid as a raw material and for improving the quality of lignin sulfonate. You can use any of the following. In the semi-rigid pavement method of the present invention, the above-mentioned rubber latex is used in an amount of 1.5 to 25% by weight based on the weight of cement.
Inject and infiltrate cement milk with a consistency of 0.2 to 0.4% by weight based on the weight of the cement containing one or more of the above additives and a flow time of 9 to 20 (preferably 9 to 12) seconds Used as cement milk. If the amount of rubber latex added is less than 1.5% by weight based on the weight of cement, cracks will occur in the paving slab to a degree that is undesirable for practical purposes, and if it exceeds 2.5% by weight, the effect of reducing construction costs will be diminished, which is undesirable. The occurrence of cracks in the paving slab can be completely prevented by using 2% or more of cement based on the weight of cement. On the other hand, if the amount of additive used is less than 0.2% based on the cement weight, the effect of reducing the amount of rubber latex blended will not be sufficient;
Even if it exceeds this value, the effect of reducing the amount of rubber latex compounded is hardly increased and it becomes uneconomical, which is not preferable. The preferred amount of additive used is 0.3% by weight based on the weight of cement. If the consistency of the cement milk is less than 9 seconds after the P funnel flows, the strength of the paving plate will be low, and if it exceeds 12 seconds, the pouring into the open-grained asphalt concrete will be insufficient, which is undesirable. In addition, in order for cement milk to sufficiently penetrate the entire height of the open asphalt layer (total penetration type), the consistency must be less than 12 seconds, but the cement milk must penetrate to a depth of about half the open asphalt layer. In the case of semi-penetration (so-called semi-permeable type), consistency can be tolerated for up to 20 seconds. In the present invention, the rubber latex and the additives may be measured and added separately when preparing the cement milk, or they may be mixed in advance at a predetermined ratio and added as a one-liquid type. In addition, rubber latex and additive materials other than the above-mentioned specific additives, such as retarders, early strength agents,
Bulking agents, stone powder, fly ash, etc. can be added. In the present invention, after pouring an open asphalt concrete layer with a porosity of 20 to 30% on a base, the cement milk composition is injected into the asphalt concrete layer using a vibrating roller or the like, and then the cement milk composition remains on the surface. A crack-free semi-rigid paving slab can be obtained by scraping off the cement milk using a rubber rake or the like. By blending specific additives into cement milk, the present invention can reduce the amount of rubber latex blended to approximately 1/2 compared to conventional methods, significantly reducing construction costs for semi-rigid pavement construction. can do. Furthermore, this cement milk has various advantages such as better permeability at high temperatures such as summer than conventional cement milk, and less amount of breathing. The present invention provides a semi-rigid pavement construction method that is low in construction cost, has excellent workability, and has good physical properties, and its industrial significance is extremely large considering the widespread use of this construction method. Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the scope of the present invention is not limited by the following examples. Example (1) Open-grained asphalt concrete Paving asphalt with a degree of inclination of 80 to 100 was used as the first
For open size aggregates with the particle size distribution shown in the table
Open-grain asphalt concrete with a porosity of 25% containing 3.5% by weight.

[Table] (2) Rubber latex Styrene-butadiene copolymer rubber latex: Solid content 42.5% by weight (3) Additives (a) Formaldehyde condensate sodium salt of naphthalene sulfonic acid (abbreviated as NSF): Commercially available cement dispersant ( (b) Sodium formaldehyde condensate of sulfonic group-containing melamine (abbreviated as SMF): Commercially available cement dispersant (c) Calcium lignin sulfonate (abbreviated as LIG): Commercially available cement dispersant (4) Mixing of cement milk and consistency Cement milk of various formulations was prepared, and the consistency was measured by P roll flow time. Table 2 shows the blending ratio and P funnel outflow time.

[Table] Cement: Onoda ordinary Portland cement used, W〓C〓50%
* Weight % based on cement weight
(5) Construction test Among the cement milks shown in Table 2, cement milks No. 1, 2, 4, 8, 11, and 12 whose consistency falls within the range of P funnel flow time of 9 to 12 seconds were used. We conducted a penetration type construction test and observed the occurrence of cracks. (b) Construction test Open-grained asphalt concrete was poured to a thickness of 5cm over an area of 9m x 10m on the foundation.
The whole area was divided into 6 sections, each section measuring 3m x 5m. Pour cement milk corresponding to No. 1, 2, 4, 8, 11, 12 in Table 2 into each compartment,
After sufficiently injecting and permeating into the voids of the asphalt concrete layer using a vibrating roller, the cement milk remaining on the surface was scraped off to the same level as the asphalt concrete layer using a rubber rake. The temperature at the time of construction was 25°C and the weather was sunny. (b) Test results Table 3 shows the results of observing the surface condition of the paving slab 7 days after construction.

[Table] As is clear from Table 2 No. 10, if the amount of rubber latex mixed without using additives is reduced, W/C =
At 50%, the consistency condition P funnel outflow time of 9 to 12 seconds cannot be satisfied. As is clear from Table 3, No. 12, the occurrence of cracks cannot be prevented by adding only additives. As is clear from Table 3, the amount of rubber latex compounded in the present invention is the same as when no additive is used (No.
This is approximately 1/2 of the amount of rubber latex compounded in 11).

Claims (1)

[Scope of Claims] 1. In a semi-rigid pavement construction method in which a layer of open-grain asphalt concrete with a porosity of 20 to 30% is cast on a base, and then cement paste or mortar is injected and penetrated to form a pavement slab: (a) 1.5 to 2.5% by weight of rubber latex based on cement weight in terms of solid content (b) 1 selected from the group consisting of formaldehyde condensates of aromatic hydrocarbon sulfonic acids, formaldehyde condensates of sulfonic group-containing aminotriazines, and lignin sulfonates. 1. A semi-rigid pavement construction method characterized by using a cement paste or mortar containing 0.2 to 0.4% by weight of one or more species based on the weight of cement and having a consistency of P funnel runoff time of 9 to 20 seconds.