AU654755B2 - A method of sand anchoring in pavement works - Google Patents

Description

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1 PATENTS ACT 1990 654755 COMPLETE SPECIFICATION FOR OFFICE USE Short Title: Int. CI: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: S Related Art: Related Art: Name of Applicant: SAddress of Applicant: Actual Inventor: Address for Service: TO BE COMPLETED BY APPLICANT IWATA CO. LTD.

3589, Nishikaizuka Iwata-shi, Shizuoka-ken, Japan Hirotaka Imazu ANDERSON-TAYLOR.& ASSOCIATES, Registered Patent Attorneys of 10 Harrison Avenue BONNET BAY N.S.W. 2226 Complete Specification for the invention entitled: A METHOD OF SAND ANCHORING IN PAVEMENT WORKS The following statement is a full description of this invention, including the best method of performing it known to me: -1- BACKGROUND OF THE INVENTION The present invention relates to a method of sand anchoring in pavement works.

When paving material such as interlocking blocks, colored flat sheets or stone is laid down on the surface to be paved, the underlying ground is sanded or the paving material is jointed with sand to provide a cushioning layer which serves to prevent destruction of the paving material by horizontal or, vertical exterpal force, after it has been laid down.

•coo However, sand itself lacks in tackiness. Hence, when sand is simply scattered over the underlying o

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co°° e ground or the joint, it is washed away or moved away due to such factors as rainfall, vibration and wind, resulting in the loss of its cushioning properties or U.0.

00. otherwise causing other trouble. More illustratively, the following problems arise.

0. i. The paving sand and joint sand, when laid down on the surface having a gradient of 10 degrees or more, 6o: are washed away at a rainfall intensity of 2,500 mm or more per hour, resulting in the loss of their cushioning properties.

2. When the paved surface is a driveway having much traffic or a container yard with heavy vehicles on, the paving sand and joint sand move due to vibrations, resulting in the loss of their cushioning properties.

3. At a shopping district, the joint sand is carried by wind into shops, contaminating goods or articles displayed therein.

4. On a pool side, the joint sand is washed out by a cleaner, causing barefoot passengers much trouble, and is likely to flow into the pool.

In order to overcome these problems, there has so far been no choice but to blend sand with cement for its anchoring. Alternatively, paving sand has been fixedly sandwiched between upper and lower fabric layers.

In the former approach, however sand loses its own cushioning properties due to the presence of cement.

This approach has another disadvantage; when it is applied to joint sand, the paving material is contaminated on the surface, posing an aesthetic problem. A problem with the latter approach is that it cannot be applied to, joint sand.

In view of the problems mentioned above, an object of the invention is to provide a method of anchoring paving or joint sand in pavement works, while the sand maintains its own cushioning properties.

SUMMARY OF THE INVENTION According to the invention, the object mentioned above is achieved by the provision of a method of anchoring paving or joint sand in pavement works, in which a uniform solution of 3.0% to 7.0% by volume of a watersoluble prepolymer in water is scattered over the paving or joint sand to form a resinated layer, said prepolymer being obtained by the reaction of a compound having at least two hydroxyl groups at one end and having a polyoxyalkylen chair with the molecular weight lying in the range of 1,000 to 20,000 with a polyisocyanate compound in a molar amount that is equal to or larger than the number of the hydroxyl groups.

According to the invention, a scattering material composed mainly of the water-soluble prepolymer having the composition mentioned above is scattered over paving or joint sand, so that the sand can be anchored in place while it maintains its own cushioning properties.

The scattering material is prepared by subjecting the water-soluble prepolymer comprising a isocyanate compound to hydration-by-polymerization reaction to form a rubbery product. In other words, the watersoluble prepolymer is homogeneously dissolved in water to form the scattering meterial, which is then scattered over sand to form on the surface of sand a rubbery form of resinated layer by hydration-bypolymerization reaction. The scattering material is also allowed to penetrate into sand due to a lowering of its viscosity by its water solubility, so that sand particles forming a layer of a certain depth can be solidified to form a rubbery form of resinated layer.

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The water-soluble prepolymer is so strongly bonded to sand particles by the hydration-by-polymerization reaction that it is greatly resistant to sand flow or movement. The resulting resinated layer foams during the hydration-by-polymerization reaction of the water-soluble prepolymer, yielding heat-insulting, closed cells that are effective for preventing frosting or freezing of sand.

The water-soluble prepolymer is dissolved in any desired water to form a solution of uniform concentration. The hydration-by-polymerization reaction may be regulated between about five minutes and thirty minutes. At this time, all excessive water o* is included in the solidified mass.

S. In the invention, the water-soluble prepolymer may be used at a concentration of 3.0 to calculated as prepolymer solid matter, and any desired strength may be obtained by regulating the concentration within this range. The, water-soluble prepolymer does not solidify at a concentration less than but it yields a rubbery form of resinated film or layer at a concentration in the range of 3.0 to The resinated film or layer swells in the presence of rain.

It is noted that the water-soluble prepolymer, when used at a concentration higher than is so increased in viscosity that difficulty is involved in uniform scattering.

The water-soluble prepolymer used for carrying out the invention is obtained by permitting a compound having at least two hydroxyl groups at one end and having a polyalkylene chain with the molecular weight lying in the range of 1,000 to 20,000 (hereinafter called the polyalkylene oxide compound) to react with a polyisocyanate compound in a molar amount that is equal to or larger than the number of the hydroxyl groups at to 120 °C for 30 minutes to 7 days, if required, in the presence of such a catalyst as dibutyltin dilaurate or triethylenediamine, thereby introducing the isocyanate groups in both ends of the polyalkylene oxide compound.

The water-soluble prepolymer is liquid or paste state at normal temperature. The solidification of the water-soluble prepolymer by the addition of water may Sbe promoted by the addition of a basic substance such as an amine compound or delayed by the addition of an acidic substance such as an acid chloride compound.

The polyalkylene oxide compound referred to in the present disclosure is a compound having at least two terminal hydroxyl groups, which is obtained by the addition of a long chain form of alkylene oxide to a compound having active hydrogen.

The compounds having active hydrogen, for instance, may be polyols such as ethylene glycol, glycerin, trimethylol-propane, trimethylolethane, pentaerythritol, sorbitol, sucrose and methyl glucoside amines such as ethylenediamine, diethylenetriamine and methylamine, carboxylic acids and esters such as tall oil, rosin acid, adipic acid and castor oil, and compounds having at least two hydroxyl groups, which are obtained by the reaction of aldehyde with other compounds olefins and aromatic hydrocarbons).

Compounds obtained by the addition of ethylene oxide or possibly other alkylene oxides to the compounds having active hydrogen or their mixtures are excellent in water solubility. In view of water solubility and the viscosity of the resulting aqueous solution, the prepolymers obtained by the reaction with the polyisocyanate compounds are desired ,to have a O* polyalkylene oxide chain having a length to such an extent that the permeability of the aqueous prepolymer solution into the end ground layer is not adversely Saffected. Alternatively, the prepolymers are required to have a polyalkylene oxide chain and a range of molecular weight which enable them to have similar permeability by the addition of dispersant, solubilizing agents, etc.

0 Thus, the polyols, for instance, polyethylene glycol has suitably a molecular weight of 1,000 to 20,000, preferably 1,000 to 4,000. This also holds for other polyalkylene oxides.

For the synthesis of the prepolymer according to the invention, 2 to 8 moles (by weight) of the polyisocyanate compound is permitted to react with 1 mole (by weight) of the polyalkylene compound.

However, this ratio may be chosen depending on the number of the hydroxyl groups in the polyalkylene oxide compound.

The concentration may be determined in such a range that the resulting prepolymer is well soluble in water and the viscosity of the aqueous solution is not considerably increased by the magnitude of the molecular weight thereof.

The polyisocyanate compound used in the invention may be a compound composed chiefly of an organic compound and having at least two isocyanate group, by way of example but not by way of limitation, a *e* diisocyanate compound such as tolylene diisocyanate, diphenylmethane diisocyanate, diphenyl diisocyanate, naphthalene diisocyanate, xylylene diisocyanate or hexamethylene diisocyanate, or a triisocyanate compound such as triphenylmethane triisocyanate.

The alkylene oxides used in the invention, by way of example but not by way of limitation, may be ethylene oxide, propylene oxide, butylene oxide, styrene oxide and epichlorohydrin.

i EXAMPLES S.o Reference will first be made to examples of synthesis of water-soluble prepolymers.

Synthesis Example 1 A water-soluble prepolymer was obtained by the reaction of 200 parts of a copolymer diol having an average molecular weight of 3,000 containing ethylene oxide and propylene oxide at a weight ratio of 85 to with 52.2 parts of tolylene diisocyanate at 90'C for 3 hours. This prepolymer is liquid at room temperature, and provides a stable compound that undergoes little change with time, when sealed up.

Synthesis Example 2 A water-soluble prepolymer was obtained by the reaction of 694 parts of polyoxyethylene glycol having an average molecular weight of 1,000 with 306 parts of tolylene diisocyanate at 90 °C for 2 hours.

Synthesis Example 3 A water-soluble prepolymer was obtained by the reaction of 780 parts of polyoxyethylene glycol having an average molecular weight of 2,000 with 220 parts of xylene diisocyanate at 90 °C for 2 hours.

Synthesis Example 4 A water-soluble prepolymer was obtained by the reaction of 748 parts of polyoxyethylene glycol having an average molecular weight of 2,000 with 252 parts of 1 hexamethylene diisocyanate at 70°C for 5 hours.

Synthesis Example A water-soluble prepolymer was obtained by a two-hour reaction at 90 °C between 740 parts of a copolymer polyol having an average molecular weight of 2,000 which was obtained by the addition of ethylene oxide and propylene oxide to glycerin at a ratio of moles to 6 moles, and 260 parts of tolylene diisocyanate.

.Synthesis Example 6 A water-soluble prepolymer was obtained by the reaction of 822 parts of polyoxyethylene glycol having an average molecular weight of 4,000 with 178 parts of tolylene diisocyanate at 90 0C for 3 hours.

Synthesis Example 7 A water-soluble prepolymer was obtained by a three-hour reaction at 70 "C between 843 parts of a copolymer polyol having an average molecular weight of 4,000, which was obtained by the addition of ethylene oxide and propylene oxide to ethylene glycol at a ratio of 72 moles to 14 moles, and 157 parts of xylene o: diisocyanate.

Synthesis Example 8 A water-soluble prepolymer was obtained by a five-hour reaction at 700C between 889 parts of a copolymer polyol having an average molecular weight of S8,000, which was obtained by the addition of ethylene oxide and propylene oxide to glycerin at a ratio of 126 moles to 41 moles, and 111 parts of hexamethylene diisocyanate.

Synthesis Example 9 A water-soluble prepolymer was obtained by a four-hour reaction at 90°C between 925 parts of a copolymer polyol having an average molecular weight of 15,000, which was obtained by the addition of ethylene oxide and propylene oxide to ethylene glycol at a ratio of 240 moles to 77 moles, and 75 parts of tolylene diisocyanate.

Synthesis Example A water-soluble prepolymer was obtained by a three-hour reaction at 90 °C between 657 parts of a copolymer polyol having an average molecular weight of 4,000, which was obtained by the addition of ethylene oxide and propylene oxide to sorbitol at a ratio of 77 moles to 10 moles, and 343 parts of xylene diisocyanate.

Synthesis Example 11 A water-soluble prepolymer was obtained by a six-hour reaction at 70 °C between 754 parts of a *s* copolymer polyol having an average molecular weight of 6,000, which was obtained by the addition of ethylene oxide and propylene oxide to sorbitol at a ratio of 110 moles to 20 moles, and 246 parts of hexamethylene diisocyanate.

Synthesis Example 12 A water-solublq prepolymer was obtained by the reaction of 800 parts of an ethylene oxide-to-castor oil adduct having an average molecular weight of 4,000 with 200 parts of tolylene diisocyanate at 90 °C for 4 hours Application Example 1 Paving sand was laid down on a slope having a gradient of 20 degrees in the form of a 3-cm thick layer, followed by rolling. Then, a scattering material consisting of a mixture of 5 parts of the 1 0 water-soluble prepolymer of Synthesis Ex. 1 with parts of water was uniformly scattered over the sand layer in an amount of 2.0 Q per m 2 After that, interlocking blocks were provided on the sand layer, followed by applying joint sand. An additional scattering material consisting of a mixture of 5 parts of the water-soluble prepolymer with 95 parts of water was uniformly scattered over the block layer at a proportion of 1.5 e per m 2 One hour later, a continued, uniform supply of water was provided on the slope, and the sand was neither washed away nor moved away. The layer set up by the polymerization of the water-soluble prepolymer with water was about 5 mm in thickness. Before the scattering material solidified, the block layer was cleaned up (this holds for the following application examples).

Application Example 2 Paving sand was laid down in a 3-cm thick layer n a driveway having mpch traffic or a container yard with heavy carrier traffic, followed by rolling. Then, a scattering material consisting of a mixture of 5 pa ts of the water-soluble prepolymer with 95 parts of water was uniformly scattered over the sand layer at a proportion of 2.0 per m 2 After that, interlocking blocks were provided on the sand layer, followed by applying joint sand. An additional scattering material consisting of a mixture of 5 parts of the water-soluble prepolymer with 95 parts of water was uniformly scattered over the block layer in an amount of 1.0 to Q per m 2 After one-ho aging following scattering, the paving sand and joint sand were not moved. The layer set up by the polymerization of the water-soluble prepolymer with water was 5 to 7 mm in thickness.

Application Example 3 After interlocking blocks had been laid down on a pavement and jointed with sand, a scattering material consisting of a mixture of 5 parts of the water-soluble prepolymer with 95 parts of water was uniformly scattered over the block layer at a proportion of 1.5 Q per m 2 The sand was not blown off by wind.

Application Example 4 After interlocking blocks had been laid down on a 90 6 pool side and jointed with sand, a scattering material consisting of a mixture of 5 parts of the water-soluble prepolymer with 95 parts of water was uniformly scattered over the block layer at a proportion of 1.0 per m 2 One hour later, a continued, uniform supply of water was provided on the pavement, and the sand was neither washed away nor moved away.

According to the invention, the water-soluble prepolymer having a predetermined composition is scattered over paving sand or joint sand, thereby anchoring the sand in place while it maintains its own cushioning properties. Thus, the paving or joint sand can be anchored in place while its own cushioning 1 2 properties remain intact.

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Claims (2)

1. A method of anchoring paving or joint sand in pavement works, in which a uniform solution of 3.0% to 7.0% by volume of a water-soluble prepolymer in water is scattered over the sand to form a resinated layer, said water-soluble prepolymer being obtained by the reaction between a compound having at least two hydroxyl groups at one end and having a polyoxyalkylene chain with the molecular weight lying in the range of 1,000 to 20,000 and a polyisocyanate compound in a. molar amount that is equal to or larger than the number of the hydroxyl groups.

2. A method of anchoring paving or joint sand in pavement works, said method being being substantially as described herein with reference to the examples. Dated this 19th day of September, 1994 IWATA CO. LTD. By Our Patent Attorney MICHAEL ANDERSON-TAYLOR -14- ABSTRACT OF THE DISCLOSURE A method of anchoring paving or joint sand in pavement works is porvided, in which a uniform solution of 3.0 to 7.0% of a water-soluble prepolymer in water is scattered over the sand to form a resinated layer. The water-soluble prepolymer is obtained by the reaction between a compouni having at least two hydroxyl groups at one end and having a polyoxyalkylene chain with the molecular weight lying in the range of 1,000 to 20,000 and a polyisocyanate compound in a molar amount that is equal to or larger than the number S of the hydroxyl groups. This method enables the sand to be anchored in place while it maintains its own *c cushioning properties in various pavement works. 0