Design Method And Performance Evaluation Of Emulsified Asphalt Cold Recycled Mixture With Portland Cement

Prosperity of our country's economy promotes the development of transportation enterprise. By the end of 2007, the total highway mileage of our country has achieved 3,570,000 kilometers, of which the freeway is 53,000 kilometers. The freeways built in the 1990s have already entered the stage of heavy and medium maintenance. A massive material, abandoned in the bitumen pavement maintenance, rehabilitation and reconstruction, is reused through cold recycling, a saving resource and energy and protecting environment recycling method, which is of important significance now and in the future in highway construction.Portland cement, with propriety proportion, can improve early intensity of cold reclaimed mixture using emulsion asphalt, and make up the deficiency of it. But, at present, cement is just used as filler which is added in experiential in design process of the mixture at home and abroad. So the researches on the mixture taking into account the respective infections of asphalt and cement specially are few. Through lots of laboratory tests, this thesis systematically discusses the design method and performance of the mixture, and contrasts with the ordinary hot mix asphalt technical specification.The test results show that the specimens of emulsified asphalt cold recycled mixture with cement are completely dry after being cured in the oven (fan closed) at 60°C for 3 days, which has represented the ideal condition of cold recycled asphalt mixture. The optimum water content can be determined according to the principle of maximum dry weight density. The optimum binder to aggregate ratio decreases when cement content increases. Resilient modulus at 20°C and 15°C and Indirect Tensile Strength (ITS) at 15°C and 25°C all do not have obviously change when cement content increases. The dynamic stability at 60°C changes from 44cycles/mm at 0% cement content to 8,000cycles/mm at 6% cement content rapidly. The dynamic stability at 40°C has the relative comparison significance, changing from 4,500cycles/mm to 21,000cycles/mm. Increment range of Tensile Strength Ratio (TSR) in 0 day, 7day and final curing time at 2% cement content are all more than 20%. But TSR in various curing time do not increase more when cement content increases again. While, the failure strain of emulsified asphalt cold recycled mixture with cement at -10oC decreases when cement content increases, changing from 1,700μεto 4,000με. When cement content is more than 2%, the failure strain at -10oC does not meet the specifications in which failure strain of hot modified asphalt mixture is no less than 3,000μεat the lowest temperature of -37oC in winter frigid cold areas.