Research On Mechanism And Application Technology Titanium Gypsum Impedance Semi-rigid Base Cracking

Semi-rigid base possess the properties of high rigidity,high bearing capacity,strong plate and anti-freezing and anti-erosion ability.which is prefered in "strong thin base surface" design system for high-level highway basic layer.But the inherent defect,shringkage cracking,make the pavement structure destroy early.This will make the consservation later more difficult and increase the cost for maintenance and road usage greatly.The current ways to prevent cracking mainly focus on the design of aggregate gradation,the limitation of cement dosage and the cleanliness of aggregates and the control of construction process,but these methods can not eliminate cracking from the origin.In order to deal with acidic waste water in sulfuric method for titanium dioxide production,lime(or carbide slag)is added to neutralize large amounts of acidic wastewater,after which dregs are produced.The dregs with dihydrate gypsum as the main component are titanium gypsum and scarcely used.The emission of titanium gypsums not only takes up a lot of land,pollutes the environment,but also put a great financial burden on business producing titanium dioxide.Industrial waste-titanium gypsum,the main material for resisting base cracking,are formed into composite cementitious material with cement and fly ash,which are mixed into the semi-rigid base.This can improve performance in the semi-rigid base and make full use of industrial waste,achieving the purpose of energy-saving,emission reduction and waste utilization.In this thesis,based on the composition analysis of the raw materials and the microscopic mechanism of reaction between cement,titanium gypsum and fly ash,the influence of blending ratio on the strength and deformation of the cement paste was studied.The formation rule of ettringite swell body in cementitious material specimen was determined by scanning electron microscope(SEM),and the usability of the method was proved by microscopic mechanism.Then,the proportion of different cementitious materials was adjusted,and the mechanical properties and deformation properties of cement stabilized macadam were tested.By comparing the test data,the law of shrinkage is obtained,and theapplication proportion of cement: titanium gypsum and fly ash is determined as 1: 0.2:0.3.Through a series of research,a new way of thinking and methods is provided from the theory and practice to solve the semi-rigid base cracking.The research results can guarantee to break through the upper limit of semi-rigid basement strength under the premise of reducing shrinkage cracking,which greatly improved the fatigue life of semi-rigid base and opened up a new direction for road structural design.