Requirements for transportation of Concrete
The contents of the mixer shall be discharged in one continuous operation and the concrete transported in such a manner that there shall be no segregation of its constituents. If, in the opinion of the Engineer, any segregation of the concrete materials has taken place during transport, the concrete shall be again turned over and mixed just before it is finally placed in position. No water shall be added to the concrete between the time of mixing and placing except on the written instructions of the Engineer.
Whilst being transported from the mixer to the site of placing, all concrete shall be properly protected from contamination by dust or sand and from excessive moisture gain or loss from rainfall or high temperature, and all equipment used shall be purpose-made for the correct transportation of concrete.
Each batch of concrete delivered to the Site shall be accompanied by a delivery ticket, a copy of which shall be handed to the Engineer’s representative at the time the delivery is made. The following minimum information shall be printed, stamped or written on the delivery ticket:
Name or number of ready-mixed concrete depot:
Serial number of ticket
Name of location of site
Grade or mix description of concrete, including minimum cement content.
Type of cement
Nominal maximum size of aggregate
Type or name of admixture, if included, and the dosage quantity
Quantity of concrete in cubic meters
Time of loading, defined as the time of contract between cement and aggregates or when these are surface dry, between cement and added water.
The contractor shall complete the following items of information on the delivery ticket after the discharge of each batch of concrete:
Arrival and departure times of the truck
Time of completion of discharge
Details of extra water or any other materials added on site
Position in the Works where concrete is placed
In the case of truck mixed concrete, the water may be added either at the concrete supplier’s plant or under the Contractor’s supervision after arrival at Site, but not in transit. Transporting the concrete mixture manually is only applied for the distance not over 200m. If the concrete mixture is segregated, need to re-mix before filled into formworks. When using the hung containers to transport the concrete mixture, the concrete mixture poured into the hung containers is not exceed 90 – 96% of the container volume.
Transporting the concrete mixture by truck or specific vehicle, need to ensure for the following requirements:
The thickness of the concrete layer in the truck body need to be greater than 40 cm if using self-dump truck;
If using specialized vehicle, both in transportation and mix, the transportation technology is determined by technical parameters of using equipment.
When using concrete pump for transportation, need to ensure for the following requirements:
The components and slump of concrete need to be tested and trial pumped in order to ensure for the concrete quality and constructing condition, concurrently, suitable for technical function of pump equipment.
When constructing in the hot conditions, the exterior surface of pipe need to covered or white painted in order to limit the radiation from the sun to heat the concrete.