Experiment Research On Rapid Pavement Repair Of Airfield Runway By Employing Polyurethane Materials

Polyurethane has many properties ,such as curing quickly, binding firmly withother materials, storing easily and using conveniently. Therefore many countries havebeen developing researches on rapid pavement repair of highway and airfield byemploying polyurethane foam since 1990's. According to the requirement of rapidpavement repair for airfield runways by employing polyurethane foam, polyurethanefoam composite materials and its composite structure are studied in this paper.The experiment is composed of two parts: surface course experiment and basecourse experiment. The material used for surface course of runway is polyurethaneconcrete, and the surface course experiment is for the purpose of seeking an optimummixture proportioning in which the concrete can meet strength demand as well asconstruction operable time. The material used for base course of runway ispolyurethane foam stabilized aggregate,and the base course experiment is for thepurpose of selecting suitable construction materials and their component ratio whichcan not only foam and cure rapidly but also meet mechanical properties that the basecourse requires.Orthogonal test is used in the surface course experiment. The effect of aggregate,polyurethane-curing agent ratio, solvent-polyurethane ratio, catalyst-polyurethaneratio, binder-aggregate ratio and temperature to early strength of the polyurethaneconcrete are analyzed in the orthogonal test, and the optimum combination of factorsis determined. On the basis of the results of the orthogonal test, other differentpolyurethanes and curing agents have been attempted. Also, the test which extendsthe level of polyurethane-curing agent ratio has been carried on. Then we select theoptimum polyurethane and curing agent, determine the final optimum mixtureproportioning. The specimens based on the final optimum mixture proportioning havebeen made to test the early strength. The result shows that the optimum mixtureproportioning is that polyurethane adopts PU-1, curing agent adopts JB-2(theconcentration is 40 percent), sand and gravel filled with cement are used foraggregate, polyurethane-curing agent ratio is 1 to 1, catalyst-polyurethane ratio is 1 to80 and binder-aggregate ratio is 1 to 8.5. Polyurethane concrete can provide highstrength in short curing age;therefore it is appropriate material for rapid repair.The aggregate available for the base course includes soil, sand, graded graveland concrete blocks. Their foaming time, curing time and unconfined compressivestrength are tested separately so that we can make a feasible project for the basecourse construction. When polyurethane foam stabilized gavel or concrete blocksunder normal temperature have cured for 3 hours, their unconfined compressivestrength are 4.13 MPa and 1.89MPa separately, which is satisfy the requirement oflime stabilized soil and cement stabilized soil in some relative code(GJB1112-1991).