Method for stabilizing unpaved road

Abstract

Compaction and / or stability of soil and / or aggregate used in unpaved roads may be improved by adding cellulose ether and water to the soil and / or aggregate prior to compaction.

Description

Technical Field

[0001] The present invention relates to the field of road construction. Background Art

[0002] About half of all roads in the United States are unpaved, and other countries have even higher percentages. Unpaved roads are usually topped with soil or aggregate, which is a blend of rock particles ranging in size from as small as sand.

[0003] The construction of an unpaved road typically involves the following steps: (1) clearing and grading the road to create the desired cross-section, and adding ditches and culverts to manage water; (2) laying one or more layers of loose road material (soil or aggregate); (3) leveling and grading each layer of loose road material after laying; and (4) compacting the road material at the end or layer by layer. In some cases, the road is constructed of two or more layers of aggregate, with one or more layers of larger aggregate as the base and one or more layers of smaller aggregate as the surface. In some cases, the road is further stabilized by chemical means, most commonly cement and / or lime.

[0004] Maintenance of unpaved roads involves similar steps. Ditches and culverts are maintained to ensure adequate drainage. A new loose road material surface is provided by: (1) scarifying (breaking up and turning up) the existing surface to eliminate ruts, vegetation, and other irregularities; and / or (2) adding a new layer of loose road material; (3) leveling and grading each layer of loose road material after it is laid; and (4) compacting the road material at the end or layer by layer. Optionally, the road can be stabilized again by chemical means.

[0005] Construction and maintenance procedures for unpaved roads are described in many publications, such as "Gravel Roads Construction and Maintenance Guide (August 2015)" published by the Federal Highway Administration of the USD department of Transportation, FHWA Publication No.: FHWA-OTS-15-0002; and "Dirt and Gravel Road Best Management Practices (2019)" published by the Culpeper Soil and Water Conservation District of Culpeper, VA.

[0006] Proper compaction of road materials is an important step in construction and maintenance. Compaction stabilizes the layers of a road, making it more resistant to vehicle traffic and erosion. The improved stability caused by compaction also reduces the amount of dust generated by vehicle traffic on the road.

[0007] It is known that water can be sprayed on loose road materials to aid compaction. In addition, various chemical additives can be added to water and sprayed on unpaved roads to help stabilize the road and control dust. Magnesium chloride and calcium chloride draw moisture from the air, keeping the road slightly damp. Lignin sulfate, clay, vegetable oil or latex can all help to make particles of road material adhere to each other, thereby stabilizing the road material and reducing dust. Portland cement can be mixed into the road material layer to stabilize it.

[0008] There is therefore a need for alternative methods to improve compaction and ultimately stabilise road materials using inexpensive and environmentally friendly ingredients. Summary of the invention

[0009] One aspect of the present invention is a method of stabilizing a soil or aggregate layer, referred to as "road material," in an unpaved road, the method comprising the steps of:

[0010] a) providing an unpaved road comprising a layer of loose road material, wherein the layer of loose road material further comprises (1) a water-soluble nonionic cellulose ether in an amount of at least 0.05 wt. %, based on the weight of the road material in the layer excluding water, and (2) water;

[0011] b) compacting the loose road material layer containing the cellulose ether and water.

[0012] A second aspect of the invention is a road comprising a soil or aggregate layer called "road material" containing at least 0.025 wt% of a water-soluble nonionic cellulose ether based on the weight of solids other than water in the road material layer.

[0013] We have found that water-soluble nonionic cellulose ethers aid in the compaction of road materials, thereby improving the stability of the road. Without wishing to be bound, we hypothesize that the cellulose ether temporarily reduces the friction between particles of the road material, allowing the road to compact better and provide a more solid surface. The cellulose ether is water-soluble and biodegradable, so that it can later be washed off and / or degraded by microorganisms, leaving behind particles that are compacted but no longer lubricated by the cellulose ether. DETAILED DESCRIPTION

[0014] The present invention starts with an unpaved road containing a layer of loose road material (soil and / or aggregate), which also contains cellulose ether and water. "Loose" means that the road material layer can be further compacted by known means (such as using compaction or rolling equipment) to substantially stabilize the layer. In some embodiments, a loose road material layer has been added to the road. In some embodiments, a loose road material layer has been built in place by loosening the existing surface. In some embodiments, the loose road material layer has been leveled and / or graded. In some embodiments, no compaction equipment (such as a roller, tamping machine, or vibrating plate compactor) is used to compact the loose road material layer.

[0015] The design principles of unpaved roads are well known and published. In some embodiments, the road cross section is designed so that the finished road has a crowned running surface, shoulder areas on each side of the road that slope away from the edge of the running surface, and ditches outside each shoulder area to receive water from the shoulder area and safely direct the water away from the running surface. In some embodiments, the road cross section is designed so that the finished road has a slightly sloped running surface, a single shoulder area on the downhill side of the road, and ditches outside the shoulder area to receive water from the shoulder area and safely direct the water away from the running surface. In some embodiments, vegetation may be planted in the ditches to reduce erosion.

[0016] Typically, the surface along the length of the road surface is designed to be substantially flat. In some embodiments, the slope may not exceed 6% for a soil running surface, or 10% for an aggregate surface, but a short distance slope of 15% may be allowed on a crushed stone surface if necessary. In some embodiments, culverts may be passed under the road to safely carry water from one side of the road to the other without causing erosion.

[0017] The running surface and shoulders may contain one or more layers of road material. If more than one layer is used, the top layer is called the surface layer and the lower layer is called the base layer.

[0018] In some embodiments, the road material may include soil. In some embodiments, the road material may include aggregate. In some embodiments, the road material may include both soil and aggregate in a single layer or in separate layers. It should be understood that in many cases, a layer containing primarily aggregate may contain a small amount of soil, and a layer containing primarily soil may contain a small amount of stone or other aggregate.

[0019] Soil used as road material can contain varying amounts of sand, silt, clay, organic material, and water. For clarity:

[0020] ● Particles as small as 4.75mm (4 mesh) are generally called crushed stone.

[0021] • Particles with a size of 0.075 mm (200 mesh) to 4.75 mm (4 mesh) are generally referred to as sand.

[0022] • Particles with a size below 0.075 mm (200 mesh) that have essentially no cohesive strength after drying are generally referred to as silt.

[0023] • Particles with a size below 0.075 mm (200 mesh) that are substantially agglomerated after drying are generally referred to as clay.

[0024] In some embodiments, the soil used in the road material contains at least 65% by weight, or at least 70% by weight, or at least 75% by weight, or at least 80% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight of sand and gravel, excluding the weight of water. In some embodiments, the soil used in the road material contains at most 100% by weight, or at most 95% by weight, or at most 90% by weight of sand, excluding the weight of water. In some embodiments, the soil used in the road material contains at least 0% by weight, or at least 5% by weight of clay and silt, excluding the weight of water. In some embodiments, the soil used in the road material contains at most 35% by weight, or at most 30% by weight, or at most 25% by weight, or at most 20% by weight, or at most 15% by weight, or at most 10% by weight of clay and silt, excluding the weight of water.

[0025] The aggregate used in road materials includes rock particles, which are usually a mixture of different sizes. The aggregate used in the base layer of road materials is usually coarser than the aggregate used in the surface layer. In some embodiments, the particle size of the surface layer aggregate meets one or more specifications in Table 1. In some embodiments where the road has a base aggregate, the particle size of the base aggregate meets one or more specifications in Table 1.

[0026] Table 1

[0027]

[0028] In some embodiments, the base layer of the road material contains 50% to 70% by weight of crushed stone, 25% to 40% by weight of sand, and 0% to 10% by weight of silt and clay, excluding water. In some embodiments, the surface layer of the road material contains 50% to 70% by weight of crushed stone, 25% to 40% by weight of sand, and 10% to 15% by weight of silt and clay, excluding water.

[0029] Road materials can be classified according to California Bearing Ratio (CBR), as measured by ASTM D 1883. In some embodiments, the road material has a CBR of at least 10, or at least 20, or at least 25, or at least 30, or at least 35, or at least 40. In some embodiments, the road material has a CBR of at most 90, or at most 80, or at most 75, or at most 70, or at most 65, or at most 60.

[0030] Road materials are also classified by the Atterberg Limit of liquid limit, plastic limit and plasticity index (PI), which can be determined according to ASTM D4318. The liquid limit is the water content at which the soil behavior changes from a plastic state to a liquid state. The plastic limit is the water content at which the soil behavior changes from a semi-solid state to a plastic state. The plasticity index refers to the range of water content between the liquid limit and the plastic limit, where the soil is in a plastic state. Road materials with a low plasticity index (less than 7%) are harder and more stable in wet conditions, thus minimizing rutting, but they also tend to have a higher content of large stones, which can make the driving surface rough and increase the difficulty of planing. In some embodiments, road materials with a low plasticity index are selected for the base layer of the road surface. Road materials with a moderate plasticity index (7% to 28%) tend to contain more small stones, which makes them easier to plane to form a smooth surface, and often also contain a small amount of clay, which reduces dust. In some embodiments, road materials with a medium plasticity index are selected for the surface layer of the road surface. Road materials with a high plasticity index (above 28%) tend to rut when wet; in some embodiments, they are not used in road materials.

[0031] In some embodiments, the road material has a plasticity index of at least 0%, or at least 2%, or at least 4%. In some embodiments, the road material has a plasticity index of at most 35%, at most 30%, at most 28%, or at most 25%, or at most 20%, or at most 15%, or at most 10%. In some embodiments, the surface layer of the road material has a plasticity index of at least 2%, or at least 4%, or at least 6%. In some embodiments, the surface layer of the road material has a plasticity index of at most 20%, or at most 15%, or at most 12%, or at most 10%. In some embodiments, the base layer of the road material has a plasticity index of at least 0%, or at least 1%, or at least 2%. In some embodiments, the base layer of the road material has a plasticity index of at most 8%, or at most 6%, or at most 5%.

[0032] In some embodiments, the depth of the loose road material layer is at least 5 cm, or at least 10 cm, or at least 12 cm, or at least 15 cm, or at least 18 cm, or at least 20 cm. In some embodiments, the depth of the loose road material layer is at most 100 cm thick, or at most 80 cm, or at most 60 cm, or at most 50 cm, or at most 40 cm, or at most 30 cm, or at most 25 cm, or at most 20 cm.

[0033] In some embodiments, the loose road material layer is formed by transporting the loose road material to the site. In some embodiments, the loose road material layer is built by loosening (breaking and turning up) the existing surface on site, which can be realized using known equipment such as a ripper, a grader with a loosening blade, and a pulverizer. In some embodiments, two steps are carried out---loosening the road surface, and transporting and adding additional road material. In some embodiments, the loose road material is further spread, graded, and leveled to the desired shape and slope of the road.

[0034] The loose road material layer also contains water and non-ionic water-soluble cellulose ether.

[0035] In some embodiments, the cellulose ether is mixed with water and then added to the loose road material. In some embodiments, the cellulose ether is added to the loose road material separately from the water. For example, in some embodiments, the cellulose ether is mixed with the loose road material before the loose road material is deposited to form a layer, such as in a drum or mixer. In some embodiments, after the road material is laid in place on the road surface, the cellulose ether is deposited on the loose road material layer, and in some embodiments, the cellulose ether is then partially mixed in when the layer is leveled and / or graded.

[0036] In some embodiments, water is added to the loose road material before the loose road material is deposited to form a layer. In some embodiments, water is sprayed on the loose road material layer after the loose road material layer is deposited on the road surface and / or after the loose road material layer is leveled. In some embodiments, the road material contains an appropriate amount of ambient moisture, such as moisture from rainfall.

[0037] In one exemplary embodiment, the cellulose ether is mixed with the bulk road material, the bulk road material is then deposited on the road surface in a layer, the layer is subsequently spread, graded and / or leveled, and water is then sprayed on the layer. In another exemplary embodiment, the bulk road material is deposited on the road surface in a layer, the cellulose ether is laid on the layer, the layer is spread, graded and / or leveled before or after the cellulose ether is laid, and water is then sprayed on the layer. In another exemplary embodiment, the bulk road material is deposited on the road surface in a layer, the mixture of cellulose ether and water is laid on the layer, and the layer is spread, graded and / or leveled before or after the cellulose ether and water mixture is laid.

[0038] Cellulose ethers are polymers comprising cellulose in which at least some of the hydroxyl groups in the cellulose repeating units are substituted with alkoxy or substituted alkoxy groups.

[0039] Cellulose ethers contain repeating units as shown in Formula 1, called anhydroglucose units. 1 , R 2 and R 3 Each of them is hydrogen, but in cellulose ethers, R 1 , R 2 and R 3 At least a portion of R is independently substituted with an alkyl or substituted alkyl group. The remaining unsubstituted R 1 , R 2 and R 3 The radical is hydrogen. "n" is the number of anhydroglucose repeating units.

[0040]

[0041] R 1 , R 2 or R 3 The alkyl groups at the position and the substituted alkyl groups contain at least 1 carbon atom. 1 , R 2 or R 3 The alkyl or substituted alkyl groups in the position contain up to 12 carbon atoms, or up to 8 carbon atoms, or up to 6 carbon atoms, or up to 4 carbon atoms, or up to 3 carbon atoms. The alkyl or substituted alkyl groups can be straight chain, branched or cyclic; in some embodiments, they are straight chain and attached to the oxygen atom in a normal configuration or an abnormal configuration. In some embodiments, the substituted alkyl groups include hydroxyl groups, alkoxy groups or halide moieties; and in some embodiments, the substituted alkyl groups include hydroxyl groups.

[0042] Examples of common alkyl and substituted alkyl groups include methyl, ethyl, n-propyl, isopropyl, hydroxyethyl and hydroxypropyl groups. (Cellulose ethers substituted with carboxyalkyl groups are also readily available, but carboxyalkyl cellulose ethers are generally insoluble in water unless converted to salts. Therefore, many cellulose ethers containing a large number of carboxyalkyl groups are not water-insoluble nonionic cellulose ethers.)

[0043] In some embodiments, R 1 , R 2 or R 3 All alkyl and substituted alkyl groups in the positions are identical, and in some embodiments, the cellulose ether contains 1 , R 2 or R 3Mixtures of different alkyl and substituted alkyl groups in the alkyl and substituted alkyl positions, such as methyl and ethyl, or methyl and hydroxyethyl, or methyl and hydroxypropyl. Examples of nonionic cellulose ethers include methylcellulose, ethylcellulose, ethylmethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose and hydroxypropylmethylcellulose.

[0044] The average degree of substitution defines the number of R 1 , R 2 or R 3 In some embodiments, the average degree of substitution of the water-soluble nonionic cellulose ether is at least 0.75, or at least 0.95, or at least 1.2, or at least 1.5, or at least 1.7, or at least 1.9. In some embodiments, the average degree of substitution of the water-soluble nonionic cellulose ether is at most 3, or at most 2.7, or at most 2.5, or at most 2.3, or at most 2.1.

[0045] In some embodiments, the cellulose ether contains both methyl or ethyl substituents and hydroxyethyl or hydroxypropyl substituents. In some embodiments, the cellulose ether contains both methyl substituents and hydroxyethyl substituents. In some embodiments,

[0046] The degree of methyl or ethyl substitution is at least 1, or at least 1.2, or at least 1.3, or at least 1.4, and is at most 2.4, or at most 2.3, or at most 2.2, or at most 2.1, or at most 2.0,

[0047] or at most 1.9, or at most 1.8; and

[0048] The degree of substitution of hydroxyethyl or hydroxypropyl is at least 0.02, or at least 0.05, or at least 0.10, or at least 0.15, or at least 0.20, and is at most 1, or at most 0.9, or at most 0.8,

[0049] Or at most 0.7, or at most 0.6, or at most 0.5, or at most 0.4.

[0050] In some embodiments, a 2% aqueous solution of a cellulose ether has a viscosity of at least 100 cP, or at least 1000 cP, or at least 10,000 cP, or at least 12,000 cP, when measured as described in the Test Methods. In some embodiments, a 2% aqueous solution of a cellulose ether has a viscosity of at most 50,000 cP, or at most 45,000 cP, or at most 40,000 cP, when measured as described in the Test Methods.

[0051] In some embodiments, a 1% aqueous solution of the cellulose ether has a viscosity of at least 100 cP, or at least 1000 cP, or at least 10,000 cP, or at least 12,000 cP, when measured as described in the Test Methods. In some embodiments, a 2% aqueous solution of the cellulose ether has a viscosity of at most 30,000 cP, or at most 20,000 cP, or at most 15,000 cP, when measured as described in the Test Methods.

[0052] Suitable cellulose ethers are commercially available, such as under the trademarks WALOCEL, METHOCEL and CELLOSIZE. Other materials can be prepared by known methods. See, for example, US 4,845,206 and Harika K et al., "Basic Concepts of Cellulose Polymers-A Comprehensive Review.", 3(3). Archives of Pharmacy Practice 202-216 (2012). In many cases, cellulose ethers can be produced by a two-step process. In the first step, cellulose is contacted with an aqueous alkali metal hydroxide to form alkali cellulose. In the second step, the alkali cellulose is contacted with an etherifying agent suitable for producing cellulose ethers.

[0053] ● Etherifying agents for alkyl substituents include alkyl chlorides. For example, in the production of methyl cellulose, the etherifying agent is methyl chloride. In the production of ethyl cellulose, the etherifying agent is ethyl chloride.

[0054] ● Etherifying agents for hydroxyalkyl substituents include alkyl epoxides. For example, in the production of hydroxypropyl cellulose, the etherifying agent is propylene oxide.

[0055] • Mixtures of etherifying agents can produce cellulose ethers with mixed ether substituents, such as ethyl methyl cellulose or hydroxypropyl methyl cellulose.

[0056] After production, the cellulose ether is typically washed to remove impurities and dried. If it is not already in a suitable powder form, it can be ground into a powder.

[0057] In the present invention, water and cellulose ether are blended with the pavement material layer separately, or are blended with the pavement material layer together in the form of an aqueous solution.

[0058] The weight ratio of cellulose ether (excluding water) to bulk road material in the layer is at least 0.05% by weight. In some embodiments, the weight ratio of cellulose ether (excluding water) to bulk road material in the layer is at least 0.1%, or at least 0.15%, or at least 0.2%, or at least 0.3%, or at least 0.4%. In some embodiments, the weight ratio of cellulose ether (excluding water) to bulk road material in the layer is at most 5%, or at most 3%, or at most 2%, or at most 1.5%, or at most 1%, or at most 0.8%, or at most 0.6%.

[0059] In some embodiments, the weight ratio of cellulose ether to water in the loose road material layer is at least 1%, or at least 1.5%, or at least 2%, or at least 3%, or at least 4%. In some embodiments, the weight ratio of cellulose ether to water in the loose road material layer is at most 20%, or at most 15%, or at most 12%, or at most 10%, or at most 8%, or at most 6%.

[0060] In some embodiments, the weight ratio of water to loose road material in the layer is at least 5%, or at least 6%, or at least 7%, or at least 8%, or at least 9%. In some embodiments, the weight ratio of water to loose road material in the layer is at most 20%, or at most 15%, or at most 13%, or at most 12%, or at most 11%, or at most 10%.

[0061] In some embodiments, the water saturation (volume of water per unit volume of available space between particles) in the road material is at least 15%, or at least 20%, or at least 25%, or at least 27%. In some embodiments, the water saturation in the road material is at most 40%, or at most 35%, or at most 30%.

[0062] In some embodiments where the cellulose ether is premixed with water, the resulting solution has a viscosity of at least 100 cP, or at least 500 cP, or at least 1000 cP, or at least 2000 cP, or at least 5000 cP, or at least 8000 cP, or at least 10,000 cP, or at least 12,000 cP at 20° C. In some embodiments where the cellulose ether is premixed with water, the resulting solution has a viscosity of at most 250,000 cP, or at most 150,000 cP, or at most 100,000 cP, or at most 75,000 cP, or at most 50,000 cP, or at most 25,000 cP at 20° C.

[0063] While the cellulose ether and water are still well mixed with the road material, the road material is compacted. The compaction can be achieved by known means, such as using a roller, a tamping machine or a vibrating compactor. In some embodiments, the compaction is achieved using a roller.

[0064] In some embodiments, the compacting step reduces the thickness of the layer by at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%. In some embodiments, the compacting step reduces the thickness of the layer by at most 60%, or at most 50%, or at most 40%, or at most 35%, or at most 30%. In some embodiments, the thickness of the surface layer of compacting is at least 2cm, or at least 5cm, or at least 10cm, or at least 12cm, or at least 15cm, or at least 18cm, or at least 20cm. In some embodiments, the thickness of the surface layer of compacting is at most 45cm, or at most 42cm, or at most 40cm, or at most 35cm, or at most 30cm.

[0065] In some embodiments, other materials may be added to the road material layer before or after compaction, such as to provide additional stability or dust control. Examples of such materials and their uses are described in the Background, such as magnesium chloride, calcium chloride, lignin sulfate, clay, vegetable and mineral oils, polymer emulsions, and enzymes. Other materials may help particles of soil and aggregate adhere to each other, stabilizing them and reducing dust.

[0066] The method has built a road comprising a road material layer, which contains cellulose ether. The road material is loose before compaction and is firm after compaction. The road material and cellulose ether have the description and exemplary embodiments discussed. The amount of cellulose ether can meet the description given in the preceding text, or may be less amount, because water may have taken a part of cellulose ether out of the layer. In some embodiments, the amount of cellulose ether in the layer measured immediately after compaction is less than the described addition by 10%, or less by 20%, or less by 30%, or less by 40%, or less by 50%, or less by 60%. The amount of cellulose ether in the road material layer may further decline over time, because rainwater and other applied water can dissolve the cellulose ether and take the cellulose ether away.

[0067] In some embodiments, the compacted pavement materials of the present invention exhibit a yield strength that is at least 10% higher, or at least 20% higher, or at least 30% higher, or at least 40% higher, or at least 50% higher than the yield strength of a similar compacted pavement material without the cellulose ether, when measured according to the Test Methods. There is no ideal maximum value for the improvement in yield strength, but it may not be necessary to pursue an improvement in yield strength of more than 100%, or 80%, or 60%.

[0068] In some embodiments, the compacted pavement materials of the present invention exhibit a linearized friction angle of less than 36°, or less than 35°, or less than 34°, or less than 33°, when measured according to the Test Method. In some embodiments, the compacted pavement materials of the present invention exhibit a linearized friction angle of at least 15°, or at least 20°, or at least 25°, or at least 30°.

[0069] As discussed, the amount of cellulose ether in the road material decreases over time until it is essentially gone, due to rainwater and other applied water. Many cellulose ethers are biodegradable and / or non-toxic to plants and animals, so their use in the present invention poses few environmental, health and safety concerns.

[0070] Test Method

[0071] Unless otherwise stated, the measurements listed in this application were performed using the following test methods:

[0072]

[0073] Water saturation

[0074] Water saturation is defined as the percentage of the volume of voids in a soil sample that is filled with water:

[0075] Water saturation = (Vw) / VV,

[0076] in

[0077] Vw is the volume of water in the wet soil composition, and

[0078] VV is the total void volume in the total mixture determined by measuring:

[0079] ○ρi = particle density of each material except water,

[0080] ○mi = total mass of each material except soil and water,

[0081] ○V = total volume of all materials except water,

[0082] And calculate the void volume VV = V-Σ(mi / ρi);

[0083] Example

[0084] The following examples illustrate specific embodiments of the invention but are not intended to limit the broadest scope of the invention.

[0085] Preparation of soil samples :

[0086] The cellulose ethers (I1 to I6) in Table 2 were obtained. In addition, the comparative stabilized materials (C1 to C4) in Table 2 were obtained. Cellulose ethers and other stabilizers are collectively referred to as "viscosity modifying additives" or "VMAs."

[0087] Table 2

[0088]

[0089] 1—Viscosity of 1% aqueous solution measured. Other conditions are the same as listed in the test method.

[0090] 2—Viscosity measured for 2% aqueous solution, measured at 20°C as described in the test methods unless otherwise stated.

[0091] Three soil samples were mixed having the compositions shown in Table 3. All numbers are parts by weight.

[0092] Table 3

[0093] sample A B C C-788 Ottawa Sand—Coarse sand 400 400 400 730 grade sand - fine sand 120 120 120 <![CDATA[MicroWhite TM 100 medium marble grit]]> 280 200 - KaMin 35 washed kaolin clay - 80 280

[0094] The inventive examples and comparative examples formulations having the contents listed in Table 4 were prepared by dry mixing the soil sample and the viscosity modifying additive in a plastic bag in the proportions shown in Table 4 for two minutes. Each mixed sample was added to a mixing bowl (Hobart N50 mixer) containing the amount of water shown in Table 4, except for IE 41, where the cellulose ether and water were mixed together before mixing with the soil sample. The samples were mixed at 136 RPM for 15 seconds. The paste on the side of the mixing bowl was scraped off and returned to the bottom of the bowl. The formulations were mixed again at the same rotation rate. The water saturation of each sample was measured and recorded in Table 4 as described in the test method. The yield strength and linearized friction angle of each sample were measured and recorded in Table 4 as described in the test method.

[0095]

[0096]

Claims

1. A method of stabilizing a soil or aggregate layer, referred to as "road material", in an unpaved road, the method comprising: The following steps are involved: a) providing an unpaved road comprising a layer of loose road material, wherein the layer of loose road material further comprises (1) a water-soluble nonionic cellulose ether in an amount of at least 0.05 wt. %, based on the weight of the road material in the layer excluding water, and (2) water; b) compacting the loose road material layer containing the cellulose ether and water.

2. The method of claim 1, wherein the water and the water-soluble nonionic cellulose ether are mixed together and then added to the bulk road material. 3 . The method according to claim 2 , wherein the mixture of water and water-soluble nonionic cellulose ether has a viscosity of 1000 cP to 100,000 cP at 20° C.

4. The method of claim 1, wherein the water-soluble nonionic cellulose ether is added to the bulk road material separately from the water.

5. The method of claim 1, wherein the loose road material comprises primarily soil.

6. The method of claim 1, wherein the loose road material comprises primarily aggregate.

7. The method of claim 1 wherein the weight ratio of cellulose ether to bulk road material (excluding water) is at least 0.1%.

8. A method according to claim 7 wherein the weight ratio of cellulose ether to bulk road material (excluding water) is at least 0.2%.

9. A method according to claim 7, wherein the weight ratio of cellulose ether to bulk road material (excluding water) is at most 2%.

10. The method of claim 1, wherein the weight ratio of cellulose ether to water (excluding water) is at least 1%.

11. The process according to claim 10, wherein the weight ratio of cellulose ether to water (excluding water) is at most 15%.

12. The method of claim 1, wherein the cellulose ether is selected from the group consisting of hydroxyethyl methylcellulose and hydroxypropyl methylcellulose.

13. The method of claim 1, wherein after compaction, the pavement material exhibits a yield strength that is at least 10% greater than a yield strength of a similarly compacted pavement material without the cellulose ether.

14. The method of claim 1, wherein after compaction, the pavement material exhibits a linearized internal friction angle of less than 35°.

15. A road comprising a soil or aggregate layer referred to as "road material", said road containing at least 0.025 wt. % of a water-soluble nonionic cellulose ether, based on the weight of solids other than water in said road material layer.

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