The Research On Performance Of Hydrophobic Cement Concrete Pavement In Deicing Salt Conditions

The cement pavement has been widely used in highway engineering construction because of it’s advantages of good stability,large rigidity,simple construction,low maintenance cost,abundant raw materials,etc.In the northern winter of China,in order to ensure the smooth traffic,there i5 widespread use of spreading deicing salt means to clear the roads snow,but under the condition of long-term use of deicing salt,deterioration of pavement durability gradually emerged.In view of the above problems,the paper applicated super-hydrophobic protective material to pavement concrete to prepare a kind of pavement cement concrete with hydrophobic,and researched durability of hydrophobic pavement cement concrete(HPCC)in deicing salt environment.Meanwhile,by means of micro-experiment such as SEM and XRD,the surface micromorphology and crystal structure of HPCC were characterized,The main research findings were as follows:(1)According to super-hydrophobic theory,the super-hydrophobic protective material for cement pavement was developed,which was used to deal with surface of ordinary concrete specimen.Then,the HPCC model specimen was prepared by surface treatment;(2)Compared with ordinary pavement cement concrete specimen,contact angle of surface of HPCC specimen was 150.7°.The super-hydrophobic protective material had good hydrophobicity,self-cleaning and permeable properties,and its penetration depth was up to 2～3mm;(3)The results of salt-frost test showed that the surface distress of OPCC specimen in 3.5%of NaCl solution was most serious than that of other concentrations,while the mass loss rate and strength loss rate of HPCC specimen with same concentration were lower than that of OPCC specimen.In Na2SO4 solution with same concentration,the mass loss rate of HPCC specimen was only 40%of OPCC specimen in 200 times of salt-frost cycle.The combined action of NaCl and Na2SO4 solution accelerated the destruction of concrete,but the strength loss rate of HPCC specimen in 3.5%of mixed solutions of NaCl and Na2SO4 was only 48.9%of OPCC specimen.In a word,compared with OPCC,HPCC had better salt-frost resistance;(4)Micro-tests showed that the crystal structure of OPCC and HPCC was very alike,and the micro-nano rough structure formed by super-hydrophobic protective material was the key to salt-frost resistance of HPCC;(5)The hydrophobization treatment of cement pavement had a little of effect on compressive strength of it,and when the wear thickness was up to 3mm,contact angle of surface of HPCC specimen was still 96.7°.The wear test showed that the hydrophobic pavement had better wear resistance.Compared with the ordinary pavement,The skid resistance of hydrophobic pavement reduced slightly,but it still could meet the requirement of the standard.Moreover,hydrophobic pavement had considerable long-term economic benefits.