Airport Cement Concrete Pavement Rapid Repairing Technology

Cement concrete pavement is one of the important traffic pavement types in our country.Because of its high bearing capacity,good performance,meeting the needs of major transportation,cement concrete structure is widely used in civilian airport pavements.With the rapid development of the economy,traffic demand is gradually increasing and airport traffic is inevitably becoming increasingly busy.How to realize rapid repair of the busy airport pavements is becoming a major issue that the airport maintenance departments are deeply concerned.The maintenance time of portland cement restorative materials is too long and its curing condition is also strict,being hard to realize the rapid repair,which can’t meet the requirements of rapid opening traffic.As a result,repair materials with rapid condensation are increasingly receiving the attention of conservation departments.There are many kinds of fast repair material sold in the market,which performance also has very many disadvantages:the setting time is too short;the early strength grows slowly;the late strength exists the phenomenon of the reduction;construction is difficult or it cannot be constructed in large area.Because the fast repair material prices are generally very expensive,so that how to improve the economic benefit of repairing technology is another problem that repair department concerned.At the same time,there is a serious lack of airport pavement repair method in our country.In this paper,firstly,we explore the domestic and foreign research status about rapid hardening cement and the progress of using prefabricated veneer splicing method to repair damaged cement concrete pavement.The airport cement concrete road surface diseases are classified by its damage forms.Performance tests of magnesium phosphate cement rapid repairing materials are done in this paper.A new method,using precast concrete plates to realize rapid repair of the airport pavement,as well as a connecting method about precast slab,is put forward.This paper introduces the method of breaking concrete pavements quickly,named static cutting.Relying on the specification,the most unfavorable position of prefabricated plate under aircraft wheel load is calculated.Results are as follows:(1)Our team do the experiment with the performance as well as its control law of a new type of magnesium phosphate rapid repair materials;the performance test result is that the setting time meets the construction requirements and that the mobility of the repair material mechanical,mechanics index,permeability resistance,abrasion resistance and freeze resistance all meet the requirement of airport pavement repair.(2)In the performance test,the flexural strength and compressive strength after one hour is 32.2MPa,5.3MPa respectively,the late strength growing slowly,no shrinkage of the strength;initial setting time is about 10 minutes and final setting time is about 16 minutes;the average fluidity experiment data is 225millimeter;the permeability resistance data for permeability pressure is up to 1.4 MPa;the test result of abrasion resistance is 30.2gram with an average;the mass loss rate is 0.39%;the relative dynamic elastic modulus of magnesium phosphate rapid repairing materials is 78.5%after 100 times of freeze-thaw cycling test,decreasing by 22.5%compared with the initial stage,and mass loss rate is 0.43%.(3)In the research of the control influence of magnesium phosphate rapid repair materials,three typical factors,retarder,water-cement ratio and MgO specific surface area,are chosen to analys the setting time and mechanical strength of magnesium phosphate rapid repair materials.The optimum content of retarder borax is 5%,the best ratio of water-cement ratio is 8%-10%,the best specific surface area of MgO in the raw material is 2700 cm2/g.(4)B737-800 aircraft,a common type in the C#class,which can seriously impact the airport pavements,is chosen in this paper.According to the specification of MHT5004-2010 civil airport cement concrete pavement design,the mechanics calculation and analysis in the most unfavorable position of the plate are done after the repair is finished,four critical loads under a maximum principal stress respectively being 2.481 MPa,3.602 MPa,2.981 MPa,2.587 MPa.(5)According to the experience of magnesium phosphate cement repair in bridge engineering and a summary of the researches about rapid repair of airport in China and abroad,we summed up a set of rapid repair construction scheme about using precast slabs combined with magnesium phosphate cement to realize the repair of airport cement concrete pavements,which can provide a reference value to the rapid repair of busy airports.