Experimental Study On The Performance Of Asphalt Concrete Rolling Layer Combined At Low Temperature Environment

Hydraulic asphalt concrete has been widely used in the core wall dam because of its good anti leakageperformance and strong adaptability to deformation, at present most of the projects are carried outconstruction at normal temperature environment conditions. Cold regions of xinjiang’s construction periodis short, in construction are also frequently encountered mechanical failure caused by factors such as timelag, in order to meet the coming flood control elevation need appropriate to extend the construction period,considering the construction of roller compacted asphalt concrete under low temperature. But the asphaltconcrete core wall construction at low temperatures can rolling compaction or not, the roller surfacetemperature is too low can effectively combine or not is an urgent problem.This paper uses the methods of indoor test and construction site test, according to the foundation roomtemperature mix ratio determined the low temperature mix ratio; measurement the density, porosity,permeability coefficient of determination of roller compacted asphalt concrete core wall under lowtemperature environment construction, and drill core samples for mechanical test, comparative analysis thechange of physical and mechanical performance of concrete due to the change of asphalt content increasedat low temperature environment; using split test, shear tests under constant normal stress, trabecularbending tests, tensile test at the combine surface of the specimens which were made at different lowermaterials temperatures, analyze the change law of tensile properties at the different combination of surfacetemperature; Through indoor test measurement of the heating effect of different lower temperature after theupper hot material paving, observe the temperature change of compacted asphalt concrete near the surfaceat construction site, monitored the temperature change process of the core wall winter layers. The mainresults are as follows:(1) The raw materials of various technical indicators using in experiment are all meet the designspecification requirements, in order to improve the construction performance of asphalt concrete at lowtemperature, mixture ratio parameter values were: maximum diameter is19mm, grading index n is0.38,filler loading is14%, amount of asphalt from6.6%add to7.0%.(2) Field testing showed measurement the density, porosity, permeability coefficient of determinationof roller compacted asphalt concrete core wall under low temperature environment are all meet thespecification requirements; due to the increase of the strength of the asphalt content of asphalt concretedecreased slightly, deformation capacity increases, can meet the design specification requirements.(3) After the test to the specimens of different combine surface temperatures, its splitting tensilestrength, shear strength, flexural strength, tensile strength increased with the decrease of combinesurface temperature and present the trend of decrease, combined with the surface temperature of30℃compared with the base material (one molding specimens) fell10.6%,8.1%,4.5%and8.1%respectively,decreased less, can meet the specification requirements. (4) When combined with the surface temperature lower30℃after the testspecimen section is smoothrelatively, the specimens present brittle failure gradually, and combined with the surface temperaturehigher30℃after the testspecimen section is rough, between layers have large particles aggregatesembedded in each other, specimens showed ductile failure gradually, it showed that the drease of bindingsurface temperature have influence on the bond quality between the layers of asphalt concrete, but hadlittle effect.(5) The use of electric blankets during the winter heating the core wall can play a protective role to thecore wall, hot sand heating measure to the winter layer is outstanding. The upper layer hot asphaltconcrete had obvious effect on the the lower asphalt concrete binding surface, when the mixtureasphalt around160℃paving to the lower level asphalt concrete of30℃, combined with the surfacebelow10mm can reach above the specifications requirements of70℃by heat transfer.(6) Tests showed：after the binding surface temperature from the current standard70℃decreased to30℃, asphalt concrete can be compacted dense，and the strength of the bindingsurface has no significantdecrease，roller compacted level has good quality.