Trinidad NAF 501 – Silo Material – Injection Procedure
Trinidad NAF 501–silo material is a granular product (5 – 10 mm).
As the material contains bitumen, a separating agent is added to prevent coagulation. During transport and storage excessive pressure and wetness must be absolutely avoided.
Before taking over the material the mixing plant has to ensure that the silo is completely empty and dry. The silo must have a ventilation device. A possibly existing dusting should not been vibrated into the silo with he NAF-filling (bridging effect by dust concentration).
For blowing out the NAF 501 from the silo truck (with hydraulically erectable bin) the following proceeding is recommended:
- Install the boiler
- Put low pressure to the boiler (the pressure on the boiler has to be kept as low as possible – abt. 0,7 bar)
- Activate the air-blowing
- Open the material gate valve for 1/3 up to maximum 1/2
- The temperature of the compressed air should steadily be controlled (max. 25 °C); if the air compressor is running too hot it should be turned off for a short time.
- Before feeding the silo again with new material, the previous material should have been used up; “pressure storage” has to be avoided.
- The proceeding of blowing out a quantity of 20 tons takes about 2 hours
- Addition of mineral aggregates
- Addition of the filler components + Trinidad NAC/NAF (TNAC/NAF can be measured on the filler scales together with the filler)
- Addition of TNAC/NAF – if not out of filler scales – simultaneous with the beginning of the injection of the bitumen. In case the injection of the bitumen can be started only after the addition of all the other mix components, the injection of the bitumen must be started without any delay immediately after the addition of the Trinidad NAC/NAF.
- The length of the wet-mixing period has to be increased by at least 10 seconds (from the start of injection of the bitumen
- Dry-mixing periods have to be avoided or at least kept as short as absolutely necessary
- Wet-mixing periods have to be increased by at least 10 seconds, from the start of injection of the bitumen
Mixing time and Mixing period when using TNAC 0/8 and Trinidad NAF 501
- To ensure the improved quality of asphalt mixes incorporating Trinidad Natural Asphalt, the following details regarding the mixing time have to be observed as well as an increased wet-mixing period (mixing time from the start of injection of the bitumen) of at least 10 seconds.
We trust in your active support to realize this mixing recommendation, which is the result of extensive product tests and long term practical experience, and we wish you and your customers every success with the high quality natural asphalt mixture.