Study On Insulation Performance Of Asphalt Mixture

Asphalt mixture can be used not only as pavement structural material,but also as energy dissipation and insulation material..However,there is little research on the insulation performance of asphalt mixture at present.In view of this,based on laboratory tests,this paper studies the insulation performance of asphalt mixtures from four aspects:the insulation performance of asphalt and aggregate,the influence of environment and material design on the insulation performance of asphalt mixtures,the influence of damage and self-healing on the insulation performance of asphalt mixtures,and the influence of moisture content on the insulation performance of asphalt mixtures.The main conclusions are as follows:The main influencing factors of asphalt insulation performance are temperature and aging,while SBS modifier has little effect on asphalt insulation performance.After the glass transition temperature is reached,the resistance of asphalt decreases considerably;the resistance of asphalt increases to a certain extent by aging in dry environment,but the aging in wet environment is not conducive to the insulation performance of asphalt.The main factors affecting the insulation performance of aggregates are the conductivity of porous solution,the higher the conductivity of solution,the lower the insulation performance of aggregates;the higher the water absorption of aggregates,the greater the decrease of insulation performance;the resistivity of granite and limestone rock-forming minerals is similar,but the insulation performance of limestone is often worse than that of granite because of its higher porosity and water absorption.In dry environment,the resistance of asphalt mixture reaches 10¹¹Ω,and its insulation performance increases with the increase of asphalt-stone ratio.The finer the gradation of asphalt mixture,the higher the resistance.Under immersion environment,the intrusion of water or conductive solution makes the insulation performance of asphalt mixture decrease,and the resistance of fine-graded mixture decreases less than that of coarse-graded mixture.The resistance of AC-5 asphalt mixture can reach 10⁹Ωin immersion environment.The resistance of asphalt mixture decreases with the conductivity of immersed solution,and the higher the conductivity of solution,the higher the insulation performance of asphalt mixture.Bad;SBS modified asphalt can improve the insulation performance of asphalt mixture under immersion environment.Damage has a great influence on the insulation performance of asphalt mixture under water immersion environment.The higher the degree of damage,the greater the reduction of the insulation performance of asphalt mixture under water immersion environment.Under the same degree of damage,the insulation performance of fine-graded mixture is better than that of coarse-graded mixture.Self-healing has a better effect on the healing of micro-cracks in the initial stage of damage of mixture and can improve the insulation of asphalt mixture under water immersion environment.With the increase of damage degree,the self-healing effect of asphalt becomes worse and worse,and the improvement of insulation performance of asphalt mixture becomes weaker.Under the gradation of AC-5,AC-10,AC-13 and AC-16,the influence of moisture content on the insulation performance of asphalt mixture is S-shaped,which changes smoothly at first,then sharply and then smoothly.The moisture content corresponding to the two inflection points of the S-shaped curve is 0.0015%and0.006%,respectively.In practical engineering,the insulation performance of asphalt mixture can be evaluated based on the moisture content-resistance relationship of asphalt mixture.Based on the above research,it is found that the water immersion environment is the main factor affecting the insulation performance of asphalt mixture.Therefore,the fine graded mixture should be selected as far as possible for laying the energy dissipation insulation layer.The asphalt content should not be lower than the optimal asphalt-aggregate ratio.Modified asphalt and low water absorption aggregate should be preferred.In addition,the method of properly increasing the thickness of insulation layer is also beneficial to maintaining the insulation performance of asphalt mixture.