Concrete roads: materials used. installation of formwork and

Concrete roads in the United States are almost an integral element of the landscape: the use of effective technologies for preparing the base and casting of the web allows to obtain a sufficiently durable road surface that can withstand serious traffic loads.

In Russia, the situation looks somewhat different: cast concrete and concrete slabs are considered more as an alternative, applied where it is impossible to lay asphalt. And yet, new technologies are gradually being introduced, so that the emergence of such trails is also just around the corner.

Preparation for work

Materials for casting

При промышленной прокладке путей в нашей стране чаще всего применяются стандартизированные бетонные плиты для дороги.  С одной стороны, использование подобных элементов существенно ускоряет работу, но с другой – качество полотна получается относительно невысоким, и потому поверхность очень быстро изнашивается (читайте также статью «Асфальтобетонные дорожные смеси: все их типы, разновидности и марки, предусмотренные стандартами»).

Note! Special trouble is delivered by joints, which over time are deformed and turn into large potholes.

That is why the technology of casting monolithic coating is most often used in private construction. It is on it that we will stop in our article.

The estimate for the device of the concrete road according to the filler technology includes the following items:

• First, we need high-quality concrete. For laying high-speed highways, it is required to use cement meringue compositions M400 (B30) and stronger, but for the access road to a private house, M300 is enough (B22.5 - B25).
• Preparation of the base is carried out with the obligatory addition of sand and gravel.
• To provide the material with sufficient elasticity, it is reinforced with steel bars or reinforcing mesh. It uses metal parts with a cross section of 10-12 mm.
• For effective functioning and prevention of deformations, the concrete covering of roads needs to be divided into several sections by compensation seams. At arrangement of such seams special sealants are used.

In addition, we will need materials for the installation of formwork: boards with a minimum thickness of 50 mm, fasteners, steel overlays on corners, pins for fixing the frame.

Pre-treatment area

The technology of concrete roads, described in TP 147-03 "Technical recommendations on the construction of road structures made of cast concrete mixtures", provides for the mandatory preparation of the base:

• On the site selected for construction, we apply the markup.
• By marking, we carry out soil sampling, removing the top fertile soil layer and deepening approximately 60 cm in relation to the planned level of the future web..

Tip! At this stage, the instruction recommends laying drainage pipes, which should be part of a single drainage system.

• Then we pour a layer of gravel with a fraction of 40 millimeters or more on the ground foundation.. The thickness of this layer should be about 30 cm.
• From above we lay a gravel-sand pillow, bringing it to the required level. We thoroughly compact the bedding with tamping machines, constantly moistening and pouring new portions of the material.
• To check the quality of the seal, we use a steel bar with a diameter of about 10 mm.. When sticking into the base, it should be hard to deepen by 60-70 cm. If the rod passes the top layer with resistance, and then goes lightly, tamping should be continued, as the loose sections sooner or later shrink.

Method of work

Installation of decks and reinforcement

Further, the method of construction of a monolithic road of concrete involves the installation of formwork from the boards:

• Before installation, we determine the level at which the roadbed will be located. It is desirable that it be slightly higher than the ground level - then dirt will not accumulate on the roadway.
• Also, when designing the driveway to the house, it is desirable to lay a small clone in the structure for the flow of water. The optimum slope is 2-3 cm per 1 m.
• Then we install the formwork, the strength of which directly depends on the parameters of the poured cement layer. For a road 100 mm thick, boards should be no thinner than 50 mm, and a web with a capacity of 150 mm or more should be built in a formwork from a bar 100 mm thick.

In parallel with the formwork, we are engaged in reinforcement and installation of expansion joints:

• Along the edges of the roadway we install ribs made of steel strip.
• In the very road at a distance of about 40 mm from the base we lay a welded mesh with a cell of 150x150 mm.
• With our own hands we arrange temperature joints every 10-12 meters. For bookmarks, we use a strip of hardboard or similar material impregnated with bitumen, as well as rubber, plastic, etc. On top of the strip, you can put on a special cover that is set exactly at the level of the road.

Note! After the cement is polymerized, the cover needs to be removed, and the groove in its place must be filled with an elastic sealant.

Concrete Pouring and Finishing

Since road concreting requires a large amount of material, the solution for this purpose is usually ordered from large enterprises. On the one hand, the price of the material increases slightly, but we can fill a large section in one go, without interrupting and avoiding the formation of stressed sections.

The process of pouring itself is as follows:

• Using the gutters, evenly distribute the solution from the mixer inside the formwork.
• Using the rules on long handles and shovels, we perform a preliminary leveling of the plane, filling areas along the edges and removing large air cavities.
• Then a long rule (flat board or steel U-shaped profile) finally align the surface. To make it easier to work, we usually select the rule a little more than the width of the road, so that its edges can be supported on the formwork.

• In conclusion, we use the so-called “bull-ironer” - a wide board with a long handle. With it, we remove all the irregularities, at the same time sealing the top layer of the coating.

Then give the concrete to grab.

After this, we perform the finishing finish:

• To avoid cracking the fabric during drying, cut shrink seams. For cutting use a special tool - jointing, deepening at least 1/3 of the thickness of the concrete layer.

Tip! The shrink seam pitch is determined by multiplying the web thickness by 30.

• After patching we apply a relief to the surface of the material using a road brush. So we not only improve the adhesion of the coating to the wheels, but also contribute to the flow of water. Thanks to this treatment, the concrete road will last much longer!

Conclusion

Строительство дорог из бетона по описанной выше технологии вполне можно осуществлять самостоятельно. Конечно, проект получится масштабным, и затраты будут весьма существенными – но все же реализовать его можно и без привлечения профессионалов (см.также статью «Дорожный бетон: основные характеристики и особенности применения»).

If you are interested in this method of casting a monolithic coating, we recommend also to watch the video in this article containing additional information.