Pile foundation. How to concrete with Carmix?

The only task of foundation is to support the weight of the entire structure so that it does not collapse during operation. However, what to do when top layers of soil are not able to withstand the load of the structure?

Pile foundations are designed for situations where the ground is so fragile that a monolithic foundation is impractical and impossible to install due to a number of reasons:


Excessive weight of some structures (for example multistorey buildings) carries a strong horizontal load and cannot be distributed only on the upper layers of the soil.

A small area of contact with the ground

Bridge structures are built on pile foundations to support the weight of the entire structure using the depth of the piles, but not the large base area. Thus, load of unsupported part of construction distributed to lower layers.

Soil and climatic conditions

Soil and climatic conditions are the most important criteria for choosing foundation type. Monolithic foundations are unsafe in peat, clay and swampy areas, because such soils can erode. Piles allow you to transfer weight of object to deeper and stronger layers of soil. If there is groundwater under construction, it is necessary to use a pile-core foundation.

The main condition for drilling piles is strength of soil. Climate greatly affects soil. Constant low temperatures lead to permafrost or long-term freezing, when ground freezes to depth of 7 ft. and only the upper layers have time to thaw in a short summer period. Soil becomes unstable, can erode, and is prone to frost heaving during long cold periods:

Water contained in the ground turns into a solid state, volume of soil increases and has a mechanical impact on foundation walls.

Pile Types

Сonstruction of a solid pile foundation begins with soil analysis. Load of structure will lay on the support piles, which in turn can disperse weight depending on characteristics of rock layers:

End-type or standing piles

Load passes through the bottom end of the pile, which rests on a strong layer of soil or rock. As a result, pile acts as a pole and safely transfers load to solid layer.

Total bearing capacity of an end-type pile can be calculated by multiplying area of pile top by bearing capacity at specific soil depth which pile rests on.

Friction or floating piles

Such piles transfer load from structure to ground by frictional force between pile surface and soil surrounding the pile, such as stiff clay or sandy soil. In friction piles, the entire pile surface works to transfer loads from structure to soil.

Once geotechnical engineers have done calculations and provided results, methods of constructing piles and spandrels are chosen. Structures for foundation can consist of either precast concrete or cast directly at site.

There is no preferred or better method for constructing a pile-rover foundation, but each has its own advantages and disadvantages. As you have already realized, piles have a great bearing capacity regardless of whether they are precast or cast-in-place.

Drive piles

Let’s start with precast piles or, as they are also called, driven piles. To use such piles in construction, you will need to find a suitable plant of precast concrete products (PCP), which will deliver piles to your construction site in time. There might be some problems at the ordering stage.

It will be lucky if your drawings and necessary dimensions of piles for construction coincide with typical piles produced in factories. After all, many concrete factories produce a clearly defined size range for pile foundation designs. In other cases, you have to contact enterprise, which will be able to make piles according to individual order. Such a service will cost more than usual order of precast concrete and production will take much longer, which should be taken into account during planning timing.

Also precast pile foundations can be made directly on site at cost and without intermediaries in the form of concrete factories. You can build a formwork according to your own drawings and concrete at your location. and subsequently already with reinforced concrete products to carry out work process.

This requires a large area for installation of formwork, support operations around the framework, and special-purpose machinery for mixing concrete.

Carmix concrete mixers will easily produce concrete of any grade directly at your site and pour concrete formwork for pile foundation. You’ll be in control of entire foundation construction process from the very beginning – making piles and parts of the pileheads.

This method can incur additional costs of concrete components purchase, labor for formwork construction, purchase or Carmix rent for concrete mix production. However, precast concrete factories include the same expenses to your order,additionally, costs of manufacture and transportation are added to the final amount. However, don’t forget about taxes, which are also built into cost.

Carmix can produce concrete for any type of your construction needs, not just for concreting piles and pile caps. You are not buying a service package, as reinforced concrete factory, but a versatile special-purpose machinery that can mix mortars and operate in any hard-to-reach areas where concrete plants can not deliver reinforced concrete or concrete mix.

Now let’s imagine: all parts of the pile-core foundation are already on site.

You will need special equipment: a hydraulic hammer or a digger to hammer the piles. Strong vibrations will pass through construction site, which may cause dangerous situations for workers during construction of foundation. For example, destroying unstable frameworks or dropping stacked construction materials. Also, vibrations from driven piles can negatively affect soil condition. Therefore, driven piles are used when a site is built on subsident and swelling soils that are 40 feet thick or less.

Augured pile

The pile foundation is made directly on site. Reinforced frame (which will not allow the soil with poor structure to deform the volume of holes) is installed and holes are drilled on the site where the structure will be located. Later, concrete mixture will be poured into these holes.

Piles are used for foundations when soil has hard inclusions in lower layers, so that load on piles is distributed over hard rocks. It is also most common to cast piles if construction is done in permafrost, swampy terrain because top layers of earth can sag and swell more than 40 feet due to soil conditions. Drilled piles can provide a secure and strong foundation because they can be designed with special expansions and recesses into the portion of the soil that will not subside.

The range of pile diameters varies from 6 to 16 inches. It is important that heads of the piles be on the same vertical level. Each pile should be poured in one go to ensure its integrity. Pouring is best done during the warm season. In conditions of low temperatures it is necessary to ensure heating of the piles for uniform setting and strength gain of concrete mixture. Concrete grade for pile foundation should be 3000 PSI or higher. The main condition for selecting the grade is degree of load from the future structure.

When selecting bored piles, you can clearly follow the design dimensional drawings of parts of structure. If you find hidden soil features, such as groundwater, diameter of boreholes can be changed at any time. At the same time, it will not be easy for you to cancel an order from a reinforced concrete factory without losing time. Also concreting piles at construction site significantly reduces cost of transportation.

You can use delivery from a batch plant or produce mix on site to provide a concrete mix for construction of pile foundation.

Ordering mortar from a concrete plant is the easiest way, which has a number of inconveniences and may not suit every site. Firstly, as with reinforced concrete factories, entire process of building a pile foundation will depend on the working schedule of concrete plant, as well as the queue for delivery.

Also, if a construction site is located in an inaccessible area, some concrete plants may refuse to deliver due to the difficulty of transporting concrete by mixer trucks or significantly increase cost due to large transport distance and topography of road.

Low quality of soil in which pile foundation is usually installed will affect movement of mixer trucks from concrete plant to construction site. Because of fluidity and instability of soil, mixers with a full load in most cases will not make it to the site of piling and will get bogged down in the ground.

You avoid time and money resources that go into delivering concrete by mixer truck, when concrete is produced on site. You can control quality of mortar components as well as quality of the mix. If there are changes during construction, you can easily change concrete formulation. Usually you make adjustments to composition of mixture due to variability of weather, which affects soil and solidification of poured concrete.

Concrete mixer Carmix of any model is ideal for construction of pile structures. The range of concrete mixers offers a wide choice of models to suit different concrete volumes on your worksite. When pouring a pile foundation, it is best to rely on flow rate of concrete mix per pile.

For example, when volume of one hole is about 3 cubic yards, it is best to use Carmix 2.5 TT with a concrete yield of 3 cubic yards, so that you can concretize one pile in one mixing cycle or get a Carmix 5.5 XL for pouring two piles in one mix.

Construction projects where pile foundations are required take place in an area with special conditions: permafrost, mountainous, uneven terrain, soft soils with a high probability of subsidence. Carmix mixes concrete easily and delivers it to place of casting, regardless of the type of soil, terrain and weather, unlike conventional concrete mixers from concrete plants.

Maneuverability of Italian concrete mixers will help unload mixture even in the most unnegotiable areas and concrete head wells. Special-purpose machinery can withstand a road slope of 30 ° and is equipped with all-wheel drive transmission and all-terrain wheels to ride over uneven ground surfaces and get out of soft ground.

Carmix can also drive in three driving modes: crabbing, synchronous and asynchronous. These drive modes allow the machine to get as close to the pouring area as possible and dump concrete. Models 3.5 TT and 3500TC have a mixing drum that can rotate 300° around its axis for more convenient concreting.

This allows the self-loading concrete mixer to get as close as possible to poured head well, thanks to its driving characteristics, and then turn the drum to shorten the distance and unload concrete.

It is important to use concrete grade specified in design documentation when pouring piles, because strength of future structure depends on it.

Concrete mix should be mobile to ensure that pile frame is poured without voids. Carmix is able to provide fresh concrete with good flowability.

Pile foundations are especially popular for construction in cold climate regions. Carmix concrete mixers can easily produce and pour concrete even in sub-zero temperatures and are well suited for work in northern states.