RU2057831C1 - Method for strengthening the base of preferentially motor roads - Google Patents

Abstract

FIELD: motor road building. SUBSTANCE: loose coarse crushed stone bed distributed along lower base is impregnated with dry mixture of homogeneous cement and sand mixture by the way of explosion and distribution using a road grader. The mixture is distributed through a design width and thickness with subsequent compacting and impregnating with water. The strengthened base is compacted repeatedly. EFFECT: high quality of the road bed. 2 tbl

Description

 The invention relates to the construction of roads, to the construction of the foundations of pavement.

 Known methods of strengthening the crushed stone foundations of pavement using a spell method having an elastic modulus of 350 MPa (BCH 46-83, p.101), processing not to the full depth of the sand-cement mixture by the mixing method (SNiP 3.06.03-85, p.33.35), having an elastic modulus of 500 MPa (VSN 46-83, p.101).

 The disadvantages of the proposed methods include: low modulus of elasticity, technological difficulties in the operation of stationary mixing of crushed stone with a cement-sand mixture.

 There is a method of building a crushed stone base of the road by laying on top of calcined limestone seedlings followed by rolling (ed. St. N 483477 class E 01 C 7/10, BNO N 33). The disadvantage of this method is: the strengthening of crushed stone only to a depth of 2-3 cm; their immediate use on the road, otherwise they will be extinguished and the strengthening effect will disappear; energy consumption for calcining limestone.

 A known method of impregnating a crushed stone base with a cement-sand mortar by the indentation method, having an elastic modulus of 500 MPa, (BCH 46-83, p. 101). The disadvantage of this method is the difficulty in distributing the CPU mixture over the surface of the crushed stone base and the additional use of vibrating platform equipment for drowning the CPU mixture in the intergranular space with its uneven distribution over the depth of the crushed stone layer, low elastic modulus.

Closest to the proposed technical essence and the achieved effect is a method of impregnating a crushed stone base with a dry cement-sand mixture (Yu.M. Vasilieva et al. Road clothes with bases made of reinforced materials. M. Transport, 1989, pp. 160-161). The disadvantage of this method is: increased consumption of cement-sand mixture of 90 kg / m ² ; moistening of the cement-sand mixture immediately after its distribution over the surface, which leads to the formation of voids in the intergranular space due to clumping of the cement-sand mixture and increased friction between this crude mixture and the surface of the crushed stone grain, and a thin cement-sand crust on the surface of the crushed stone layer from material that has not passed into the intergranular space, which is not involved in strengthening the crushed stone layer; low elastic modulus of the reinforced crushed stone layer of the base of the pavement, equal to 810 MPa.

 The purpose of the invention is to improve the filling of the inter-crib space with a sand-cement dry mixture of increased density, increasing the elastic modulus of the spent CPU with a mixture of crushed stone.

 This goal is achieved in that the non-compacted, coarse gravel layer distributed over the lower base is impregnated with a dry mixture of evenly mixed cement and sand by the method of its removal and distribution by the grader to the design width and thickness. The entire cement-sand mixture easily passes through the intergranular slots of unconsolidated crushed stone (especially low-strength limestone, not subject to crushing during rolling).

 Then, a 10-pass compaction is carried out with a roller on pneumatic tires so that the cement-sand mixture not only completely fills the intergranular space, but also is maximally compacted there for the subsequent creation of a dense cement-sand stone, until the cement-sand mixture is completely saturated with the subsequent compaction operation 3 -6 passes with rollers on pneumatic tires.

 Thus, the compacted layer of crushed stone and cement-sand mixture increases not only the density, but also the elastic modulus, which exceeds the elastic modulus of the material by 1.5 times.

 PRI me R 1. A metal mold with a size of 10 × 10 × 30 or 20 × 20 × 20 cm was covered with quarry low-strength limestone refractory crushed stone of size 20.40, 40.70 mm.

Then metered cement-sand mixture composition, wt. Portland cement 18 Fly ash 12 Quartz sand 70,
which amounted to 1 cm ^{2 of the} base with a thickness of 10 cm 52 kg (or 9.36 kg PC, 6.24 kg ZU, 36.4 kg P), it was poured from the surface of the crushed stone layer until the intergranular voids were completely filled.

 After completion of this operation, the crushed stone layer with the cement-sand mixture was compressed by vibration of 10.13 s with the load of a pressure-simulating vibration wheel with 10 passes.

Then, the entire cement-sand layer was wetted with water in an amount of 27-35 lt per 1 m ² .

 The layer was again vibro-compacted for 4–7 s.

 After 28 days of exposure, the vibro-compacted cement-sand mixture reinforced with a cement-sand mixture was subjected to both stamp tests (BCH 46-85) and prismatic specimen destruction with deformation detection using dial gauges (standard tests) to determine the elastic modulus (initial deformation modulus).

 The result showed that such a reinforced crushed stone material has an elastic modulus of from 1500 to 1800 MPa.

 PRI me R 2.

 Filling a metal mold with crushed stone to a design height that simulates a crushed stone base.

 Impregnation with a dry cement-sand mixture of intergrain space to 1/2 part the height of the crushed stone layer.

 Vibration compaction 10.13 s.

 Impregnation of the upper half of the height of the crushed stone layer.

Water spillage of the entire layer of crushed stone base 27.35 l / m ² .

 Vibration seal 4.7 s.

 The elastic modulus of reinforced crushed stone by this technological process amounted to 2400 MPa.

 Below is an indicative comparative table 1 on the technology of strengthening the crushed stone layer with the calculation of economic efficiency by known and proposed methods.

Economic efficiency per 100 m2 ^of area will be C ₁ -C ₂ = 154.14-90.0 = 54.14 rubles.

Thus, using a different method of strengthening low-strength limestone crushed stone, it is possible to obtain a more durable reinforced crushed stone, which exceeds the known modulus of elasticity of the known value of 1.48, respectively; 1.85; 2.96 times with an economic effect of 54.14 rubles. per 100 m ^{2 of the} area of the fortified foundation of pavement.

The costing of the cement-sand mixture with the preparation of 1 m ^{3 is} given in table.2.

Claims (1)

 METHOD FOR STRENGTHENING THE BASIS OF PREVIOUSLY AUTOMOBILE ROADS by successively laying coarse fractioned crushed stone and dry cement-sand mixture on it, moistening and vibration compaction of the base, characterized in that prior to wetting, additional crushing of crushed stone and dry cement-sand sand mixture is completed until they are completely filled.

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