Preparation And Improvement Of Cold Patch Asphalt Mixture

As a new repair material, cold asphalt mixture is more popular amoungthe departments of road maintance due to the features of constructions atroom temperature, less pollition of environment, non-closed road traffic, lessweather restrictions. As a result of expensive imported producrs and lack oftest methods and evaluation indicators about cold patch asphalt mixture inthe domestic, product quality was uneven, such as: low initial MarshallStability (MSi), strong temperature sensitivity, weak water stability, shortlife. This had a serious impact on the promotion and application of coldpatch asphalt mixture in the pavement maintenance industry, and it wasn’tbeneficial to improve the roas traffic condition. In this paper, the testmethods and evauation indicators were proposed based on related literaturesand actual performance of products, and the optimum preparation conditionsof asphalt mixture were determined by the Marshall test and the rutting test.Then the improvement of mixture with microcrystalline wax (M-Wax) andAttapulgite (AT) was studied by the systemic performance tests. Finally, theimprovement mechanism of M-Wax and AT was preliminaryly discussed.The specific content:1. Cold patch asphalt mixture was prepared by mixing diesel, soybeanoil, base asphalt, basalts as raw materials. The optimum preparationconditions were determined by the Marshall test and the rutting test, andthey were that: the composition ratio (weight) of cold patch asphalt—baseasphalt: diesel: soybean oil=80:13:5, blending temperature—140℃,blending time—30min, mixing temperature—30℃, amount of cold patchasphalt—4.5%.2. The systemic performance tests were carried on about the mixturewith M-Wax, and the result show that①the optimum amount of M-Waxwas5%;②the viscosity of cold patch asphalt with M-Wax at60℃andhigh temperature performance of asphalt mixture with M-Wax could be improved, but the effect of M-Wax was limited;③the strength and waterstability of asphalt mixture with M-Wax could be obviously improved, andat the optimum the initial Marshall Stability (MSi)was over4.5kN, themolding Marshall Stability (MSm) was over9.5kN, the residual MarshallStability (MS0) reached75.1%;④the mixture with M-Wax displayedgood lessening and compaction, and were mixed conveniently at lowtemperature.3. The systemic performance tests were carried on about the mixturewith M-Wax, and the result show that①the optimum amount of AT was5%;②the viscosity of cold patch asphalt with AT at60℃and the strength,water stability, high temperature performance of asphalt mixture with ATcould be obviously improved, and at the optimum the viscosity of cold patchasphalt at60℃reached4.6Pa s, the initial Marshall Stability (MSi)wasover4.6kN, the molding Marshall Stability (MSm) was over9.7kN, theresidual Marshall Stability (MS0) reached90%, the dynamic stability (DS)reached369.562time/mm;③the mixture with AT displayed goodlessening and compaction, and were mixed conveniently at low temperature.4. The improvement mechanism of M-Wax and AT was preliminarylydiscussed about microstructure and thermal properties by scanning electronmicroscopy (SEM), differential scanning calorimetry (DSC) and atomicforce microscopy (AFM) and other testing methods.