From internal pipelines, drains are transported by external ...
It must be said that the problem of how to manually compact gravel is quite relevant in private construction. No, of course, we are not talking about global projects, such as, for example, ramming rubble pillows under the foundation of a house with an area of \u200b\u200bover 100 square meters. m. here, you certainly will need special tools in the form of an asphalt compactor or a construction vibrating plate, since the volume of work is too large, and this will resemble the “sunset by hand”. Let's talk about small forms: a parking lot in the country, a path in the garden or the like. When you can really cope - and this is real and tested on the experience of many - on their own, without resorting to the help of expensive teams!
How to tamp gravel by hand? The problem is not easy: in the sense, physically. But its technical resolution has several options invented by our powerful inventions and savvy people. We will talk about them in our article today, but first, about some general principles of ramming.
Why do you need to ram gravel?
Frankly, the problem is quite interesting and some are not entirely clear. And among beginners in the construction business, this is the most common question. It would seem that he covered the surface with this strong and strong material, leveled it all - you can cover it with a final coating, what can happen, because a stone is a stone?
But not so simple. As you know, crushed stone is not a simple stone, natural (like gravel), but crushed in an artificial way. It is durable, but has sharp corners due to the technology of its production. Thus, additional tampering of the material creates a denser fit of individual fractional fragments to each other, and excessive voids between them disappear or are reduced in volume. This creates an additional margin of safety for laying.
We listen to the opinions of professionals. They confirm that the compaction of crushed stone during construction is necessary without fail.
The exceptions may be such options when the natural soil on which work is being carried out is rocky. Then it will be sufficient to thoroughly level the gravel before the subsequent laying of concrete, tile or asphalt on it. In all other cases, the idea is this: crushed stone as a base should not just lie in the ground, but form together with it such a compacted mixture by ramming with a dense filling of cracks between fractional fragments with soil. The thickness can vary for different purposes from 50 to 250 mm or more (this depends on what kind of load the final coating will experience in the future). Now that with the theory - why tamping is necessary - everything is more or less clear, we are moving, so to speak, to practical exercises.
Manual tamper
When there is no vibrating plate and roller at hand, ramming tools can be made with your own hands. But we repeat, these mechanisms, driven by the muscular strength of man, invented by craftsmen, are relevant only for tamping not too large fragments of surfaces, or those that subsequently will not experience too powerful loads on themselves.
There are many options for how to make a device for manual tamping. The simplest one is as follows. We take a wooden beam with a cross-section of at least 100X100 mm, and better - 150x150, then we get a wider grip of the rammed surface. The height of the beam should be convenient for work (usually about the chest performing tamper).
From timber rounded 50x50 mm, we make handles that we nail to the base with nails and fastenings made of iron or galvanized sheet. The bottom of the device is also sheathed with galvanized sheet to increase strength. In principle, the simplest device, known, probably, even at the time of the pharaohs, is ready for use. Of course, he did not get too much surface capture area for tamping, but if there is free time and desire, they can tamp even a crushed stone pillow under the foundation, for example, a small outbuilding.
True, it will take more time and energy to do this than when using a gasoline vibrating plate, but as an option, it is actually quite widely used. Using such a manual mechanism is quite simple, however, it requires some physical preparation, because you really get tired. We lift the device by the handles and lower it with force, for example, onto a garden path covered with gravel. Repeatedly repeat the movement, moving in a given direction. Thus, you need to go all the way several times.
One note: There are many options for such a device. There are more durable ones made of a metal pipe of about the same diameter with a metal “leg” welded to the base. True, this design creates too much vibration when applied (which, for example, dampens a wooden device), and then work should be done with special gloves.
DIY skating rink
The same applies to the manual asphalt compactor, which is also used with might and main for compacting small fractions of crushed stone (especially for various track options). To make it, in the presence of a grinder and a welding machine, as well as certain materials, is not difficult. Cut a metal pipe with a diameter of at least 30 cm to a length of one meter. On the one hand, we weld with a metal sheet and cut it in a circle with a grinder. Precisely in the middle of the sheet there should be a hole for fixing subsequently the handle.
Turn the pipe open end up and fill in the sand. The other end is also welded with a sheet and cut around the circumference. We put on the device for manual tamping a handle from a bent pipe. It turned out a universal device that, due to its weight, can be used for tamping small gravel, and for laying asphalt in the yard, and for sand and soil to make them denser. Using it is quite easy, but it will also require some skill and good physical development from you.
More options
If, for example, you need to tamp a small parking lot for your car in the country, then you can use the following method, invented by the people and successfully used, since there is nothing particularly complicated in technology. So, we sprinkle crushed stone over the territory measured in advance and marked with pegs (be sure to leave a certain amount of it on bedding).
We level it with a shovel so that the layer everywhere is the same thickness. Then we get behind the wheel of a car and methodically begin to park in the future parking lot in various places - either in the center, then on the left, then on the right, then sideways - trying to maximally cover the space covered with rubble. We do the procedure many times (20, 30, 50), until we are convinced that the rubble is tamped over the entire plane by the weight of the car. Shallow ruts may appear in some places. Pour the prepared crushed stone into them and continue. Here is such a simple but effective way, however, it is not entirely obtained manually, but using the weight of your car.
A well-prepared base is the result of the durability of the industrial floor and the building as a whole. Soil compaction methods are different, one thing remains the same - the use of special compaction equipment. The soil is compacted to increase its ability to withstand heavy loads. The principle of operation is based on air displacement. At maximum compaction, its content is not more than 3-5%.
When installing a concrete floor slab on a soil foundation, it is necessary to carry out work on planning the existing soil foundation. Peat, plant soil, construction debris must be removed. Clay soils also need to be removed to a depth of about 0.5 m. This is necessary to create a “trough”, which is subsequently filled with sand and gravel to create the bearing capacity of the base. Sandy soil removal is not required. Sandy soils consist of small particles of 0.1-2 mm in size. Dense sand is an excellent basis for the construction of structures, because it has a small compression ratio.
Depending on the loads acting on the soil base, a calculation is made. Depending on the loads, the thickness of the sandy, gravel, and sand gravel are determined. The fraction and material of crushed stone, soil compaction coefficient, etc. are also determined.
Compaction Methods.
To select a compaction method, you need to know several parameters - humidity, degree of uniformity, the desired density of sand or gravel, season, and so on. Compaction is carried out only with a certain percentage of sand moisture, so if necessary, moisten the soil with watering hoses. Compaction of frozen soils cannot be made. Before the start of the sealing phase, a test seal is carried out. Usually the test section is not larger than 3dx3d, where d is the diameter of the rammer.
Basic soil compaction methods:
- rolling - using rollers
- tamper
- vibratory ramming
Very often, several methods are combined.
When rolling, static pressure is transferred from the roller to the ground. It is carried out by self-propelled and trailed skating rinks. The thickness of the sealing layer is 35-50 cm. Several passes are required in the same place.
Conventional ramming is based on the transfer of impact force from a discarded seal (large mass slab) to the ground. This method has a large load, which provides compaction of crushed stone and sand to a depth of 2 m. It is carried out using ramming plates weighing 1-2 tons, which are dumped from a height of 1-2 m. For small volumes of work, manual ramming is performed - it is used for compaction sand in small volumes.
The most common soil compaction method is vibration ramming. This method is based on the transmission of mechanical vibrations. Vibration compaction is carried out by vibratory rollers, self-propelled vibratory rammers and vibrating plates. The thickness of the compacted sand or gravel is 30-50 cm.
Sand preparation works are carried out in layers, with compulsory compaction by vibratory rollers, and in places near walls and columns by vibrating plates and rammers. The sand compaction factor should be at least 0.95. The upper preparation layer is usually made from crushed stone of a fraction of 40-60 mm, followed by a rasklantovanie crushed stone of a fraction of 5-20.
In the case of shallow groundwater, the crushed stone base must be separated from the floor plate (to exclude the rise of water vapor) using a plastic film (two layers of 200 μm) or a waterproofing membrane.
All materials for the preparation of the base must comply with GOST. The resulting base should not have differences of more than 20 mm over the entire area. The compaction of crushed stone and sand increases the strength of the soil, reduces compressibility. The process is mandatory to ensure the strength of the base and foundation.
The average cost of preparing a soil base.
| № | Name of works | Cost |
| 1 | Sampling of the earth trough with the subsequent removal and planning of the territory under the mark | 450 rub / m 3 |
| 2 | Sand base with 50 mm thick seal |
90 rub / m 2 |
| 3 | The device of crushed stone base with a seal thickness of 50 mm from limestone crushed stone | 180 rub / m 2 |
| 4 | Sand base with 100 mm thick seal | 140 rub / m 2 |
| 5 | The device of crushed stone base with a seal 100 mm thick of limestone crushed stone | 280 rub / m 2 |
MINISTRY OF TRANSPORT CONSTRUCTION
STATE ALL-ROAD ROAD SCIENTIFIC RESEARCH INSTITUTE
Approved by the Director of the Union State, Candidate of Technical Sciences E.M. Good
Approved by Glavdorstroi
(Letter No. 5603/501 of 08/01/83)
Moscow 1985
The design of crushed stone foundations treated with a sand-cement mixture, developed by the Union, Hyprodornia and State Dorodnia, provides a method for determining the calculated modulus of elasticity of a layer; requirements for a sand-cement mixture and crushed stone treated with a sand-cement mixture. Recommendations are given on the selection of mixtures that provide the required strength and frost resistance of the base layer; according to the technology of building a crushed stone base, treated in the upper part with a sand-cement mixture using two methods: mixing using a profiler and pressing using a vibratory roller, cam roller and pneumatic tire roller. The need for quality control of construction is indicated. 2, tab. 8.Foreword
The pace of pavement construction is constantly growing. The relevance of the task is increasing - to develop the construction of the foundation using local materials and to propose appropriate technology that would improve the quality and efficiency, as well as accelerate the construction of foundations with increased load-bearing capacity. "Guidelines for the construction of crushed stone substrates treated with sand-cement mixture" were developed based on the results scientific research and experimental work of the Union, Hyprodornia, State Doroga and the construction of pilot plots by the Magistraldorstroy trust of Glavdorstroi and other organizations. These Guidelines describe the design and construction technology of a crushed stone base treated in the upper part with a sand-cement mixture or other inorganic binders. The proposed base design and technology of its device allow: to increase the bearing capacity compared to widespread crushed stone and gravel substrates and reduce material consumption by 10 - 20%. reduce cement consumption by 10 - 20% due to edema of coarse-grained materials in comparison with fine-grained materials with a smaller amount of binder; to ensure that construction vehicles can pass on the base without destroying it due to the manifestation of load-bearing capacity at an early age due to the skeleton of the material compared to sand and soil cement; to lengthen the construction season due to the removal of crushed stone in winter and the final construction of the base in the summer, which reduces the need for vehicles in the summer; use mixing plants with a small capacity and for high-speed construction of foundations due to the smaller volume of mixed material; reduce fuel consumption by 10 - 20%, reducing the volume of road transport compared to transportation in the construction of traditional crushed stone or gravel substrates; reduce labor and energy costs for mixing the mixture due to less work on the mixing plant. The total economic effect of reducing material consumption, reducing the consumption of binder and fuel and energy resources during the construction of 1 km the estimated cost is approximately 1 - 6 thousand rubles. The novelty of the work is protected by copyright certificates: No. 903446, No. 960348, No. 483477, No. 924211. “Methodical recommendations” were made by candidates of technical sciences V.S. Isaev, V.M. Yumashev, A.O. Sall, I.Z. Dukhovny, O.N. Rudaya, engineers N. A. Yorkina, M.F. Fomina, V.M. Beskrovny, V.M. Belousov, E.V. Volkov.1. General Provisions
1.1. These Guidelines are developed in the development of SNiP II-D.5-72 and SNiP III-40-78 and are intended for use in the construction of crushed stone substrates treated in the upper part with a sand-cement mixture or inorganic binders based on production waste (metallurgical slag, whitewash sludge, active fly ash, etc.). 1.2. The crushed stone layer should be treated with a sand-cement mixture by the mixing method and the impregnation-indentation method. When using the mixing method, the necessary processing depth is provided by adjusting the working bodies of the DS-108 type profiler, which distributes a layer of crushed stone and sand cement using a screw-cutter and then mixes them. When using the impregnation method - indentation, the working depth depends on the voidness of the crushed stone layer and the machines used - cam roller, vibratory roller, pneumatic tire roller. 1.3. The basis of the developed design must be arranged on an approved subgrade or underlying layer. 1.4. The length of the interchangeable gripper should be assigned based on the planned pace of construction and the availability of machines and mechanisms. 1.5. Crushed stone bases treated with a sand-cement mixture or other binders should be arranged in dry weather at an average daily air temperature of at least 5 ° C. Crushed stone is allowed to be transported in winter to intermediate warehouses to the place of future construction. 1.6. Works on the installation of foundations must be carried out in accordance with the "Safety Rules for the Construction, Repair and Maintenance of Roads" (M .: Transport, 1978) and SNiP III-A.11-70 "Safety in Construction" (M .: Stroyizdat , 1972).2. Pavement foundation structures
2.1. The average modulus of elasticity of the base structure with a modulus of elasticity variable with respect to the depth of the layer can be determined by conditionally dividing the base into two parts: the upper, treated with a sand-cement mixture, and the lower, untreated, with the corresponding calculated parameters shown in Fig. 1 and tab. 1.
Fig. 1. Diagram of the modules for the construction of crushed stone base, treated in the upper part with inorganic binders: h - total thickness of the base, cm: h 1, h 2 - thickness of the upper processed and lower untreated parts of the base layer, cm; E 1 E 2 - moduli of elasticity of the processed and untreated parts of the base layer, MPa; E cf - the average modulus of elasticity of the base layer, MPa
When designing, it must be borne in mind that the bearing capacity of the design of the crushed stone base treated in the upper part with a sand-cement mixture, characterized by the average modulus of elasticity of the layer E cf, depends on the values \u200b\u200bof the elastic modulus of the processed E 1and untreated E 2 parts and their thicknesses h 1 and h 2(see Fig. 1) with a total layer thickness h.
Table 1
|
The ratio of the heights of the layers |
The elastic modulus of the untreated part of E 2, MPa |
The value of the average modulus of elasticity of the base E cp, MPa, equal to E 1, MPA, equal |
table 2
|
Brand on the strength of crushed rock |
The calculated modulus of elasticity of the untreated part, MPa, with crushed stone size, mm |
carbonate |
igneous |
sandstone |
Table 3
|
Resistance of sand cement to compression, MPa, with the ratio Щ: ПЦ,% (K sec) |
The properties of the processed material |
Modulus of elasticity, MPa |
Bending tensile strength, MPa |
3. Requirements for the materials used
3.1. The stone materials used for the device of the proposed design should have requirements for strength, frost resistance and grain composition. For a mixture of sand with cement or other inorganic binders, requirements for composition, strength and frost resistance should be made, 3.2. The strength of crushed stone from natural rocks must meet the requirements of GOST 8267-82, the strength of slag crushed stone - GOST 3344-73.3.3. Frost resistance of crushed stone should meet the requirements given in table. 4 of these "Guidelines".TABLE 4
|
Climatic conditions |
Mark of crushed stone by frost resistance, not less, for |
grounds |
coverings |
Harsh |
Do not use |
Moderate | Soft | Harsh | Moderate | Soft |
Table 5
|
Climatic conditions |
Sand cement grade for frost resistance, not less than, for |
base layer |
top layer of the base |
coverings |
Harsh |
Do not use |
Moderate | Soft | Harsh | Moderate | Soft | Harsh | Moderate | Soft |
4. Technical and economic choice of the foundation of pavement
4.1. Depending on the depth of impregnation, as well as the required average modulus of elasticity of the base layer, the base designs shown in Fig. 2.4.2. The base design must be selected on the basis of a technical and economic comparison of the options taking into account the cost of materials and the composition of the mixture. The cost of a unit of the base construction area C npc is the sum of the cost of crushed stone C n a cement-concrete mixture C nc spent on the construction of this structure: where is the cost of 1 m 3 of crushed stone , rub.; l, in - the length and width of the plot, respectively, m; h 2 is the thickness of the lower, untreated part of the layer, K pr is the crushing compaction coefficient; K p is the loss coefficient, K p \u003d 1.03; h 1 - the thickness of the upper processed part of the layer. m; ρ shpts - the average density of the mixture of crushed stone with sand cement, t / m 3; - the content of crushed stone in the upper, processed part of the layer, a fraction of a unit; ρ nsch - bulk density of crushed stone, t / m 3. The cost of a sand-cement mixture is determined by the formula:|
|
5. Ground design
5.1. For the design of the bases, it is necessary: \u200b\u200bthe required modulus of elasticity of the base structure; the required frost resistance of crushed stone and sand cement; the thickness of the base; characteristics of crushed stone (grain composition, strength, frost resistance, initial rock); sand characteristic (particle size, type of sand by origin); cement grade; mechanisms for impregnation and the depth of impregnation of crushed stone with sand cement adopted in accordance with this; 5.2. When designing the bases, it is necessary: \u200b\u200bto determine the required modulus of elasticity of the upper, machined and lower, not processed according to the "Instruction" BCH 46-83 parts of the layer for a given general modulus of elasticity of the structure and depth of impregnation, as well as for known characteristics of crushed stone; determine (based on the elastic modulus ) the required strength of the upper, treated part of the layer; determine the necessary strength of the sand cement that provides the required strength of the processed part of the layer; check whether the frost resistance of the sand cement corresponds to the specified t fucking; determine the amount of binder in the sand-cement mixture of the required strength; determine the required amount of water in the sand-cement mixture per unit area of \u200b\u200bthe structure; determine the amount of water required to irrigate a unit area of \u200b\u200bthe crushed stone layer; set the amount of sand-cement mixture required for impregnating the crushed stone of a given grain composition to an accepted depth per unit area of \u200b\u200bthe structure; determine the consumption of crushed stone, sand and cement for a unit area of \u200b\u200bthe designed base structure. 5.3. The required modulus of elasticity of the upper, treated part of the layer can be determined by the formulas: where E cf is the design average modulus of elasticity of the structure, MPa; E 1 is the required modulus of elasticity of the upper, treated part of the layer, MPa; E 2 is the specified modulus of elasticity of the crushed stone layer, permeable by tab. 2 of these "Guidelines" depending on the strength, grain composition and breed of gravel intended for use, MPa; h 1 - the thickness of the upper processed part of the layer, m; taken on assignment, taking into account the requirements of these "Methodological Recommendations", depending on the intended construction technology; h 2 - thickness of the lower crushed stone part of the layer, m; is taken on the basis of the total required thickness of the base. The value of the elastic modulus of the upper, treated part of the layer for the most common values \u200b\u200bof the average modulus of elasticity of the layer and the elastic modulus of crushed stone layers can be found in table. 1 of these "Guidelines" .5.4. The required strength of the upper, treated part, layer can be calculated by the correlation between the strength R cr (MPa) and the elastic modulus E 1 (MPa) of this material: The strength grade of the processed materials in accordance with GOST 23558-79 for different elastic moduli should be taken according to tab. 3 of these "Guidelines" .5.5. The required strength of pescement or other binder, providing the necessary strength of the treated part of the layer R shpts should be calculated according to the dependencies:|
2.08 R sppc + 0.3 at W: PC \u003d 80:20, 1.1 R sppc + 0.8 for SC: PC \u003d 65:35, 1.2 + 1 at Щ: ПЦ \u003d 50:50. |
|
|
Table 6
|
The amount of cement,% required for processing |
Resistance to compression of sand cement, MPa |
screenings crushing carbonate rocks |
coarse and medium grained sands |
fine sand |
,
|
Q pc \u003d lv h 1 ρ pc V psc K r K p, |
Q pc \u003d lv h 1 ρ pc K p,
where ρ 1 is the density (bulk density) of grains of crushed stone, t / m 3; ρ 2 is the bulk density (bulk density) of crushed stone in a compacted state, t / m 3; To r - the coefficient of expansion of grains of crushed stone, K p \u003d 1 ÷ 1,15; V n u- void gravel, fraction of a unit; K p - loss coefficient, K p \u003d 1,03. The value of ρ 2 can be determined by compaction of 10 kg of crushed stone in a steel cylinder with a diameter and height of 234 mm with a load of 10 kg on a vibrating table with a vibration frequency of 3000 rpm min, amplitude 0.4 mm for 30 s. 5.11. When arranging the base using the impregnation-indentation method, taking into account the processing depth, fractionated gravel should be treated with 35 - 40% of the sand-cement mixture, which corresponds to the voidness of the material to be laid. 5-40 mm fraction gravel should be treated when mixing the foundation with the mixing method, taking into account the processing depth, it is advisable to process the sand-cement mixture in an amount of 20 %, which also corresponds to the voidness of the mixture. It is allowed to process crushed stone of 35 - 40 and 50% of sand-cement mixture during a feasibility study. Before starting work, to determine the consumption of sand-cement mixture, determine the voidness of the materials used and use formulas (12). The approximate consumption of sand-cement mixture for a device of 100 m 2 of a base at different depths of processing crushed stone, taking into account the surface layer of sand-cement 1.5 cm thick, is given in table. 7 of these "Guidelines".
Table 7
5.12. After the laboratory composition of sand cement has been established, the need for materials per unit area of \u200b\u200bthe base should be calculated. The required amount of crushed stone (m 3) can be determined by the formulas: where K cr - crushed stone compaction coefficient. The amount of sand (m 3) for the preparation of a sand-cement mixture should be determined by the formulas: where is the sand content in the sand-cement mixture, fractions of a unit; ρ np is the bulk density of sand, t / m 3 .5.14. The amount of cement Q c (t) for the preparation of sand cement can be determined by the formulas: where is the cement content in the sand cement mixture, fractions of a unit. 5.15. During work, amendments should be made to the calculated composition of materials, taking into account the actual moisture content of the materials. According to the formulas:|
|
6. The technology of construction of foundations by mixing
6.1. During the construction of foundations by mixing, crushed stone is taken out onto the prepared underlying layer, the amount of which should be determined taking into account the design thickness of the base and compaction coefficient. In winter, crushed stone can be transported to intermediate road storage depots in the area of \u200b\u200bthe planned construction. 6.2. Pre-distribute the crushed stone with a bulldozer or grader, and finally at the design thickness of the base, taking into account the compaction coefficient, with a DS-108 type profiler or other distributors in one pass. When distributing the crushed stone with the profiler, the cutter and the cutter blade are lifted. The auger blade is installed at the design level with a margin of seal. The auger is raised 2 - 2.5 cm above the cutting edge of the blade. 6.3. After distribution, if necessary, crushed stone should be moistened before processing with sand cement to obtain subsequently a mixture of crushed stone with sand cement of optimal moisture content (estimated water consumption - up to 10 l per 1 m 2) and rolled for passage of construction vehicles (two or three passes of the ice rink along one track). 6.4. The sand-cement mixture intended for processing the upper part of the crushed stone layer must be prepared in mixing plants of the SB-78 or DS-50A type. To ensure the quality of the mixture, the accuracy of the supply of sand is not less than ± .5%, cement and water ± 2% of the mass of the supplied material. The mixture should be transported by dump trucks or other vehicles and with the appropriate feasibility study.6.6. The sand-cement mixture must be pre-distributed with a grader, and finally laid on the surface of the distributed gravel by a profiler or other distributors. The consumption of sand cement is determined taking into account the specified depth of processing of the crushed stone layer and the ratio between crushed stone and sand cement in the treated part of the layer. The sand cement mixture is planned by the profiler in one pass at a working speed of 10 - 15 m / min. When planning, the auger and blade are raised to the thickness of the layer of the mixture to be distributed, and the milling cutter and blade of the milling machine are transported. 6.7. At the end of the distribution, the sand-cement mixture must be mixed with the crushed stone laid to the calculated (required) depth. The maximum mixing depth for the profiler should not exceed 15 cm. Mixing is performed at an operating speed of 5 m / min. milling cutter at maximum speed and auger; while the dumps are raised to the transport position, and the cutter and auger are set to the depth mark. If necessary, the resulting mixture is humidified so that the mixture has optimal humidity and is mixed again with one or two passes of the profiler. At the end of mixing, the base is planned in one pass of the profiler. The working bodies are installed in the same way as when planning the gravel. Working speed 7 - 8 m / min. 6.8. The base immediately after mixing should be compacted in 12 - 16 passes of the roller on pneumatic tires in one trace. In this case, the compaction coefficient at a depth of 5 - 20 cm should be at least 0.98. Compaction starts from the edges of the base to the middle. 6.9. Compaction should be completed within 3 hours from the preparation of the sand-cement mixture, including the time for transportation of the finished sand-cement mixture to the road section under construction, its distribution and compaction. The technological gap between the preparation and compaction of sand-slag mixture based on crushed slag or crushed slag with the addition of an activator - cement should not exceed 4 - 5 hours. When processing crushed stone with uncrushed granular blast furnace slag without activator cement or bauxite and nepheline sludge of technol cal gap may be increased to 6 - 8 hours 6.10.. At the end of compaction, the base should be finished with a profiler and finally the surface layer should be densified with a heavy smooth-roller compactor in one or two passes along one track. In the final layout, the milling cutter and blade are raised; auger blade set at the design level; the screw is raised 1 - 2 cm above the cutting edge of the blade. 6.11. At the end of the final layout, it is necessary to care for the foundation with one of the generally accepted methods used in the care of cement concrete, in accordance with SNiP III-40-78. It is allowed to lay the coating on the day of the foundation device; in this case, the care of the base is excluded. 6.12. It is necessary to open the movement of transport on a foundation constructed using cement after gaining 70% of the design strength of the foundation, but not earlier than 7 days later. after finishing work.7. Construction technology of the bases by impregnation-indentation method
7.1. The essence of processing a crushed stone layer with a sand-cement mixture is to fill a mixture of voids of the crushed stone layer under its own weight and indentation during rolling (mechanical impact), in several ways; vibration using vibrating plates of laying machines; vibration and pressure using vibration rollers; depth pressure using cam rollers; surface pressure - rollers on pneumatic tires. 7.2. Before crushing with sand cement, it should be carefully planned with a grader and poured with water in an amount of 3-10 l per 1 m 2. If necessary, to ensure the passage of construction vehicles, crushed stone is rolled with a light roller in two or four passes along one track according to SNiP III-40-78.7.3. The sand-cement mixture prepared in the installation must be distributed on the surface of the crushed stone layer by a profiler or grader. The consumption of sand-cement is determined depending on the voidness of the crushed stone and the depth of processing of the layer. The time of the technological gap between the preparation of the mixture and the end of the seal is recommended to be taken in accordance with paragraph 6.9 of these "Methodological recommendations". 7.4. For processing crushed stone by vibration, it is recommended to distribute the sand-cement mixture with stackers of the DS-97, DS-108, D-345 type, equipped with vibration sealing bodies. In this case, at the same time, in one pass of the stacker, the sand-cement mixture is distributed and penetrated into the gravel layer. 7.5. To treat the crushed stone layer with vibration and pressure, a DU-54 type roller should be used, the vibration roller of which contributes to the penetration of the distributed sand-cement mixture into the voids of the crushed stone layer in three to four passes along one trace. To process the crushed stone layer by the deep pressure method, it is advisable to use a cam roller, which during operation increases the gaps between the individual crushed stone, providing an increase in the depth of penetration of the sand-cement mixture into the crushed stone layer. It is recommended to use cam rollers of the type DU-28, DU-3A or DU-32A at a speed traffic 4 - 8 km / h.7.7. Depending on the required thickness of the treated monolithic base layer, indentation can be carried out in two ways. With the required thickness of the monolithic layer of not more than 13 cm, it is recommended to press the sand-cement mixture or other cementitious binder into the crushed stone by successive passes of the cam roller, and with a thickness of more than 13 cm - alternating passages of the cam and pneumatic or smooth rollers through each passage. The approximate number of passes of the cam roller can be assigned in accordance with table. 8 of these "Guidelines" and clarified by the results of the test indentation at the beginning of work.Table 8
Injection into the crushed stone layer of a sand-cement mixture or belite sludge by a cam roller starts from the curbs with the subsequent passages moving to the longitudinal axis of the road and overlapping the track of each previous pass by at least 20 cm.7.8. To process the crushed stone layer by the surface pressure method, rollers on pneumatic tires should be used, pressing sand cement with two or three passes of the roller along one track. Finally, the layer should be compacted after processing crushed stone using one of the previously mentioned methods follows by rollers on pneumatic tires of the type DU-29, DU-16V, DU-31 for 12 to 16 passes along one track and in accordance with paragraphs. 5.42 - 5.46 of the "Technical Instructions" BCH 184-75. When using the method of pressing by alternating passages of the cam and pneumatic or smooth rollers, the number of passes of the pneumatic roller can be reduced to five to eight due to the fact that partial compression of the base occurs simultaneously with the indentation. passages of the smooth-roller rink. 7.10. At the end of the compaction of the base, it is necessary to take care of it (see paragraph 6.11 of these "Guidelines"). 7.11. The movement of construction vehicles on the base can be opened after they gain 70% of the design strength when processing crushed stone with a sand-cement mixture or slag binders with activator cement. On the base of crushed stone treated with white clay slurry, the movement of vehicles can be opened immediately after the device. If the next day after the installation of such a base it is not intended to lay the overlying layer, then the base should be maintained by watering it daily (in dry weather) with water in an amount of 1.5 - 2 liters per 1 m 2 throughout the entire warm period before laying the overlying layer of pavement.
