The detection of asphalt wax content is essential to evaluate its physical and chemical properties. By pyrolysis distillation, this method accurately measures the wax content in bitumen samples, with the main steps including distillation, cooling, filtration, and mass determination. The process requires tightly controlled temperature and distillation rates to obtain reliable experimental results.
Purpose and Scope of Application
This detection method is designed to determine the wax content in road petroleum asphalt by pyrolysis distillation. Wax content is an important indicator to evaluate the performance of asphalt, which directly affects the physical and chemical properties of road materials.
Technical requirements for instruments and materials
Distillation flasks – used to distill bitumen samples.
Automatic cooling device - ensure that the cooling water temperature is -30°C±0.1°C.
Cooling filter device - using a sand core filter funnel with a pore size of 10~16μm.
High Temperature Furnace – Set temperature to 550°C±10°C.
Analytical balances – with 0.1mg and 0.1g accuracy.
Thermometer - measuring range -30~+60°C, indexing value 0.5°C.
Erlenmeyer flasks, glass funnels, Vacuum Pumps and other auxiliary instruments.
Chemical reagents - including anhydrous ether, anhydrous ethanol, petroleum ether (60~90 °C), etc.
Methods and Steps:
Preparation
Wash the distillation flask and tumble dry, weighing it by mass (to the nearest 0.1 g). Erlenmeyer flasks are also processed, numbered and weighed.
Preheat the furnace to 550°C±10°C.
Prepare the cooling unit, make sure it is functioning properly, and have crushed ice water ready.
Test procedure
Sample preparation – add 50 g ± 1 g of bitumen to the distillation flask and close the bottle tightly.
Set up the distillation – place the flask in a high-temperature furnace and connect it to an Erlenmeyer flask in ice water. Start heating and adjust the flame to keep the distillation rate at two drops per second.
Distillation process – distilled in 25 minutes until no distillate flows out and the remaining material in the bottle is completely coke.
Weigh the distillate – remove the Erlenmeyer flask from the cold water, cool it to room temperature and weigh its mass (to the nearest 0.05 g).
Sample cooling and filtration – the distillate is mixed with an appropriate amount of anhydrous ether, injected into a cooling cartridge, and absolute ethanol is added to dissolve it thoroughly. Cool for 1 h to promote wax crystallization.
Cryofiltration – Filters the precipitated wax and uses a Vacuum Pump to speed up the filtration process to ensure that the wax is well separated.
Wax dissolution – Wash the filter unit with preheated petroleum ether to dissolve and collect the wax.
Weigh the wax mass - evaporate the wax-containing solution to petroleum-free ether, and weigh the precipitated wax mass (accurate to 0.1mg) after drying.
Result calculation
According to the distillation results of different samples, the average value is taken as the wax content result, which is accurate to 1 decimal place (%). If the error of the repeatability test is beyond the standard, a regression analysis is required to obtain a more accurate wax content value.
Precautions
Ensure temperature control of the operating environment to avoid temperature changes affecting the results.
In case of operation error or insufficient wax precipitation, the test should be re-performed to ensure the accuracy of the results.
For the determination of wax content, several parallel tests are performed to increase the reliability of the results.
conclusion
The determination of asphalt wax content is a complex and delicate process. Through the above steps, the wax content in the asphalt can be accurately measured, which provides an important basis for subsequent material analysis and performance evaluation. This method not only conforms to domestic standards, but also refers to international advanced detection technology to ensure its reliability and effectiveness.
summary
The method for detecting asphalt wax content is not only effective and highly accurate, but also ensures the reliability of the data through reasonable experimental design and meticulous operation procedures. This detection method provides an important basis for the quality control of asphalt and helps to improve the overall performance of road engineering.
