Research On Composition Design And Performance Of Asphalt Mixture With Coal Gasification Fine Slag Blended By Salt

Coal gasification has become the mainstream technology of clean and efficient utilization of coal,but a large amount of remained coal cinder disturbed the sustainable development of coal chemical industry.It is of great practical significance to develop and utilize the fine slag from coal gasification roundly.Remarkable economic and environmental protection effects will be achieved by preparing powdery salinization for frost resistant pavement,applied into asphalt mixture,from coal gasification fine slag,which possess microporous structure and mineral composition.Firstly,the engineering characteristics of coal gasification fine slag were evaluated.The physical properties,including density,loss on ignition,particle size,grading characteristics,were measured,while the particle size and gradation characteristics were analyzed.Subsequently,the microstructure of coal gasification fine slag was observed by scanning electron microscope.The phase composition was analyzed by X-ray diffraction,and the surface information of functional groups in coal gasification fine slag was characterized by infrared spectroscopy.Secondly,the crystalline mineral salt,coal gasification fine slag,mineral fiber,hydrophilic mineral components and slow-release materials were selected.The reasonable ratio of each raw material and the preparation process were determined,and then the ball milling was carried out.The basic physical performance indexes of the salinized material,as well as its micro morphology and structure,were tested.Finally,the mix proportion design of salt storage asphalt mixture blended with coal gasification fine slag is conducted to determine the reasonable aggregate gradation and the optimum asphalt-aggregate ratio.In accordance with the rutting test,low temperature bending test,immersion Marshall test and freeze-thaw splitting test,the road performances of salt storage asphalt mixture with coal gasification fine slag,including high temperature stability,low temperature crack resistance and water stability,are explored.Meanwhile,the electrical conductivity method was used to characterize the snow melting function of the salt storage asphalt mixture mixed with coal gasification fine slag.The results are as follows:(1)The maximum particle size of coal gasification fine slag is less than 2.36 mm.The particle size of coal gasification fine slag is distributed mainly between 50 and 250 μm,which accounts for 42.9%.Its particle characteristics are similar to that of fine aggregate.The loss on ignition of finer particles reaches more than 50%.The coal gasification fine slag has a loose and porous structure and large specific surface area,which is capable of wrapping salinization.The residual carbon in the form of flocculation and other elements such as O,Ca,Si,Al,etc.,exist in fine slag.The surface of coal gasification fine slag contains aromaticity,which has certain interaction with asphalt components,promotes the interface gelation between coal gasification fine slag and asphalt components,and in turn improves the compatibility of the two phases.(2)Salt-storage asphalt mixture with coal gasification fine slag is designed by Marshall method,and the final mix ratio is: I(9.5-16 mm): II(4.75-9.5 mm): III(2.36-4.75 mm): IV(0.075-2.36 mm): V(coal gasification fine slag composite snow-melting salt)= 20:30:25:18:7.The optimum asphalt-aggregate ratio is 5.1%.(3)Salt-storage asphalt mixture mixed with coal gasification fine slag has good high-temperature stability and excellent low-temperature deformation performance.The coal gasification fine slag can play a good role in low-temperature anti-cracking ability.Both of the Marshall Stability and the freeze-thaw splitting strength ratio are greater than the standard value.The results indicate that the salt-storage asphalt mixture with coal gasification fine slag has good water stability.The snow-melting test shows that the effective components of salinization are separated in order during the immersion process of salt-containing asphalt mixture with coal gasification fine slag,signifying remarkable snow-melting effect.