Study On Pavement Performance Of Asphalt Mixture Based On Oyster Shell Solid Waste Utilization

Oysters in the process of processing and eating,will produce a large number of waste oyster shells,the current waste oyster shells in the road application research is relatively small,the domestic demand for road new construction and transformation into high-grade pavement increasing,at this time to find new road materials and reduce resource consumption has become the current trend.According to the physical indicators of mineral powder,the oyster shell is ground into a fine powder that meets the particle size requirements according to the self-made technology as a filler.Starting from the practical application of asphalt mixture,the physical and chemical characteristics of oyster shell powder were studied in detail,and finally with the goal of improving the performance of asphalt mixture,the comprehensive evaluation of oyster shell powder asphalt mixture was carried out through the road performance comparison test of oyster shell powder asphalt mixture and dolomite asphalt mixture.(1)Through the investigation of the yield distribution of oysters,it is found that the raw material output of oyster shell powder is huge,the processing and reuse cost is low,and then XRD,optical electron scanning microscope,low temperature nitrogen adsorption test and other tests are used to compare the physical and chemical properties between oyster shell powder and dolomite ore powder,and the study finds that the apparent density of oyster shell powder is 8.67% smaller than dolomite,the specific surface area is increased by 5.9%,the hydrophilic coefficient is reduced by 43%,the surface is alkaline,and the oyster shell powder also has a richer pore structure.As a filler,it can be closely combined with asphalt,which preliminarily verifies the feasibility of oyster shell powder as an asphalt mixture filler.(2)From the standard AC-13 grade of each grade of the sieve hole,select 9.5mm,4.75 mm,2.36 mm and 0.075 mm 4 important sieve holes,and their horizontal combination considering different oil-stone ratios,using orthogonal test,the gradation of oyster shell powder asphalt mixture is optimized.After the evaluation of range analysis method and ANOVA method,it is found that the 9.5mm pass rate has the greatest impact on the stability of Marshall test indicators,the ore gap rate is significantly affected by the2.36 mm pass rate,and the oil-stone ratio will directly determine the void ratio,flow value and asphalt saturation,and determine the gradation range of oyster shell powder asphalt mixture AC-13 that meets the Marshall index,and then carry out the Marshall test according to the ore gradation combined with different oil-stone ratios to analyze the indicators of Marshall test.The optimal oil-to-stone ratio of oyster shell powder asphalt mixture and dolomite asphalt mixture was determined to be 4.9% and 5%.(3)According to the gradation range of the determined oyster shell powder and dolomite asphalt mixture,the final synthesis curve was formulated and the optimal oilstone ratio was determined,and the performance of the two asphalt mixtures at high temperature,water stability and low temperature crack resistance was studied,and the performance between the oyster shell asphalt mixture and the ordinary asphalt mixture was compared,and the results showed that due to the incorporation of oyster shell powder,the dynamic stability of the oyster shell asphalt mixture was increased by 36.9%compared with the dolomite powder asphalt mixture under the condition that the ore and gradation type were the same Moreover,the relative deformation was reduced by 12.3%,and the high temperature stability was significantly improved.Compared with dolomite asphalt mixture,the residual stability and tensile strength of oyster shell powder asphalt mixture increased by 8.5% and 5.4%,respectively,and the stability of oyster shell powder water was also quite excellent.However,the maximum bending strain of the trabecular bending test was found to be reduced by 3.9%,indicating that the low temperature performance of the oyster shell powder asphalt mixture was slightly reduced,but it could still meet the normative standards.(4)Through the study of the dynamic modulus and phase angle of oyster shell powder asphalt mixture(AC-13),its viscoelastic characteristics can be better reflected,which is helpful for the structure,design and maintenance of its asphalt mixture,and is conducive to its application in road construction.The results show that the dynamic modulus is extremely affected by temperature and has obvious stress dependence.When the temperature is 5 °C and 20 °C,the phase angle of the two asphalt mixtures will decrease significantly with the increase of frequency,and at the temperature of 40 °C,the change law of the phase angle is exactly the opposite.By fitting the Sigmoidal main curve,it is found that the correlation between them is greater than 0.99,and the correlation is high.When the temperature rises or the frequency decreases,the dynamic modulus decreases significantly.In addition,at 20 Hz,the performance of oyster shell powder asphalt mixture increased by 5.9% at 5°C.The dynamic modulus at 20°C and 40°C increased by 7.7% and 7.8%,respectively,indicating that the mechanical properties of oyster shell powder asphalt mixture were improved compared with dolomite asphalt mixture.In summary: oyster shell powder has good advantages and application prospects in replacing dolomite as asphalt mixture filler,oyster shell powder asphalt mixture has greater rutting resistance and water damage resistance performance improvement,through the dynamic modulus study of oyster shell powder bitumen,analyze its mechanical properties,and also predict the dynamic modulus change law of its wide frequency through the dynamic modulus main curve,and the research results have certain engineering application value.