Precast concrete piles are used in different situations in this article you will be able to know various aspects of both their use and in what situations they can be used.
What are precast concrete piles?
As we all know, precast concrete piles have a definition very similar to that of other types of piles. Precast concrete piles are structures designed to transmit and resist the loads of a structure, these thanks to the type of depth and the materials that are manufactured are capable of supporting considerable loads. Reinforced concrete piles are divided into two categories, the first is precast piles and the second is cast-in-place piles.
Foundations with concrete piles
When starting the excavations to start a work, different problems can be evidenced before finding the firm or resistant layer where a structure is going to be laid or where the pile driving is going to be carried out. The different problems that can be found are the space that is available, the hardness of the ground to be drilled, the different conditions of the ground to support the structure and not present any type of movement, etc. It is here when the need arises to support a load that is isolated on a ground that lacks firmness, or that is difficult to access by the methods that are usually used.
Solution of failures in foundations
To solve the types of failures that a terrain or foundations presents, piles are used. The piles are the constructive elements of the deep foundations that are used in a specific way in the works, this facilitates the transmission of the loads of a superstructure and infrastructure crossing the inconsistent or loose layers, until the layers that are at a considerable depth but that have the necessary load capacity to support the structures; O well; it is in charge of distributing the loads on a floor that is characterized by being relatively soft, allowing it to pass through enough to support the structure safely.
Manufacture of precast concrete piles
Precast piles are characterized by the fact that an ordinary reinforcement is used when they are made and they have a square or octagonal shape in cross section. This reinforcement is made so that the pile can withstand the bending moment that develops when handling it and transporting it to the place where the piles are going to be driven, also to support the vertical load and the bending moment that originates from the lateral load. . This type of pile is manufactured depending on the length that is needed and they are cured before transporting them to the place where they are to be installed.
Types of concrete piles
Currently there are several techniques to make precast concrete piles, this shows that the pile industry every day perfects its production technique to prevent any type of failure in the foundations. Below we will describe some of the types of concrete piles.
Prestressed concrete piles
Precast concrete piles can also be presented as prestressed thanks to the use of prestressing cables; these piles are manufactured with high-strength steel so that they fulfill the job for which they were created.
What is prestressed concrete?
Before describing prestressed concrete, we will describe what prestressing is, this concept accounts for the intentional application of constant efforts to a structure or to different pieces, with the aim of improving resistance and behavior under the conditions of resistance and service that are needs to.
Use of the prestressed concrete technique
The techniques and principles that account for prestressing are implemented in different types of structures and materials; one of the most common uses is the design of structural concrete.
The process for making prestressed concrete consists of introducing a large amount of axial pre-compression to the beams in order to suppress any tensile stress acting on the concrete. Thanks to the practice of this technique and the progress in the different types of related knowledge, it is identified that this idea is unnecessarily restrictive, since tensile stresses in the concrete and a certain width of cracks can be allowed.
Prestressed pile technique
The prestressed piles have an ultimate resistance of their cables of approximately 260 Ksi (= 1800 MN / m2). When piling the piles, the cables are prestressed with a resistance of 130 – 190 ksi (= 900 – 1300 MN / m2) and then concrete is lost around them. After the piles are cured, the cables are trimmed which causes a compressive force to occur in the pile section.
Piles cast in place
The in-situ pile is built by drilling a hole in the ground where it is to be installed and then filled with concrete. There are currently different types of cast-in-place concrete piles used in construction and most of these have been patented by their own manufacturers. Cast-in-place piles are divided into two broad categories which are adequated and unshaped. Both types of these piles are characterized by having a pedestal at their bottom.
The piles with ademe are characterized by having a pedestal, of great consistency in an expanded concrete bulb that is created thanks to dropping a hammer on the fresh concrete.
The type of pile without casing is divided into two; one that has a pedestal and the other does not. Unsuitable piles are made by initially driving the pipe to the required depth and then filling with fresh concrete. The tube that was initially introduced is gradually withdrawn as the hole made in the ground is filled.
Precast concrete piles
This type of pile is an elongated structural element, which is made with prestressed or reinforced concrete, and its section is characterized by having a smaller side or diameter, usually less than or equal to 60 cm, which are manufactured on the surface and then they are driven into the place that has been decided to form the deep foundation of the structures, in order to transmit the loads that produce a superstructure to the ground.
A precast concrete pile is a deep foundation technique that falls within the category of piles known as displacement piles. The installation or execution of the precast piles is done by driving the precast piles, providing energy impacts that are controlled so as not to cause any damage to the pile.
Structural design of precast concrete piles
The structural design of precast concrete piles is characterized by having a shaft with a uniform circular, octagonal and square section and they are reinforced. Reinforced concrete piles are manufactured in this way in order to withstand the efforts made when handling them. Smaller concrete piles are generally 20 to 30 cm wide and are solid in most cases; larger size concrete piles are characterized by being solid or hollow in order to reduce their weight.
Structural design of prestressed concrete piles
Prestressed concrete piles provide the necessary strength despite having thick walls that are relatively thin; these hollow piles have measures of 140 cm in diameter and walls with a thickness of 10 cm, they resemble concrete pipes, they are used in many cases where a high load capacity is needed together with great rigidity.
What are concrete piles for?
Precast concrete piles are generally used in bridges, marine constructions and dock constructions. In these situations, the durability of the precast concrete pile is of great importance since they are severely exposed to the different situations that bring the elements and thanks to the fact that the concrete piles are installed on the surface of the ground, resembling a column, it does not have a lateral support with what if they count the friction piles.
Factors limiting the use of precast concrete piles
There are two factors that limit the use of precast piles, we will tell you about them below.
- In the first place, they are relatively heavy when compared to the weight of other types of pile that are similar in size.
- Secondly, it is very difficult to cut them in the cases that turn out to be very long and to increase their length in the event that you need to tie them with others of different lengths.
Compared to steel piles, concrete piles are not capable of withstanding difficult conditions at the time of being driven, which generates a high probability of being damaged in this task. Despite this, concrete piles are used in many situations because they have a lower cost compared to steel piles and their bearing capacity is considerable.