Transportation of concrete is the essential process of moving the freshly mixed concrete from its mixing location to the place where it will be used for construction.
As defined, transporting the concrete mix is the transferring of concrete from the mixing plant to the construction site. This process is crucial, especially considering that not all concrete is mixed on the actual construction site. This is most common for ready-mixed concretes, which are prepared off-site and require transport, sometimes involving significant travel distance and time.
Why Transport Concrete?
The need to transport concrete arises primarily because the optimal location for mixing (a batching plant) is often separate from the construction site itself. This is particularly true for larger projects or when using ready-mixed concrete, which offers benefits like quality control and high production volumes not feasible on every site. Efficient transportation ensures the concrete arrives in good condition, ready for placement.
How is Concrete Transported?
Various methods are employed depending on the type of concrete, the distance to be covered, the volume required, and site accessibility. The goal is always to deliver the concrete without segregation (separation of its components) or significant loss of workability.
Here are some common methods:
- Transit Mixer Trucks (Ready-Mix Trucks): The most ubiquitous method for ready-mixed concrete. These trucks have a rotating drum that keeps the concrete agitated during transport, preventing segregation and maintaining consistency. They are designed to carry large volumes over varying distances.
- Dump Trucks: Used for transporting concrete with a very low slump (stiff concrete) or for short distances where segregation is less of a concern.
- Concrete Pumps: While primarily a placement method, pumps are often fed directly by transit mixers and can be considered part of the overall transport chain, moving concrete horizontally or vertically from the delivery point to the final location.
- Buckets: Used with cranes for vertical transport on high-rise buildings or when site access is difficult for trucks.
Factors Affecting Transportation
Successful concrete transportation involves managing several key factors:
- Distance and Time: Longer distances and travel times increase the risk of hydration starting (setting) or segregation. Admixtures can be used to control setting time.
- Weather Conditions: Extreme temperatures can affect the concrete's temperature and workability.
- Road Conditions: Rough roads can induce segregation.
- Mix Design: The composition of the concrete mix influences its stability during transport.
Efficient transportation is vital for the quality and timely completion of concrete construction projects. It's a logistical challenge that requires careful planning and execution to ensure the concrete arrives at the site in optimal condition for placement and finishing.
