钢砂SBS改性沥青混凝土裂纹的感应加热自修复性能

Induction heating activated self-healing of cracks in SBS modified asphalt concrete adding steel grits

制备了带预切口的钢砂SBS改性沥青混凝土小梁试件,进行了电磁感应加热试验,分析了加热距离、钢砂粒径与钢砂掺量对SBS改性沥青混凝土裂纹自修复性能和路用性能的影响,并提出了相应导电材料使用建议。研究结果表明:加热距离越小,试件感应加热速率越大,当感应线圈距离试件顶面10mm时,试件具有较大的加热速率且便于采用红外摄像机捕捉影像;在混凝土制备时钢砂易于分散,钢砂粒径与掺量越大,混凝土的感应平均加热速率越大,其中,当钢砂体积分数为6%与粒径为1.4mm时,试件顶面具有最大的感应加热速率,为1.25℃·s^(-1);随着钢砂掺量增加,试件的感应热自修复率逐渐提升,试件顶面最高温度达到80℃时,其平均自修复率为89.2%,且当钢砂体积分数为6%与粒径为1.0 mm时,试件具有最高的自修复率,为96.2%;钢砂提高了SBS改性沥青混凝土的高温稳定性,但是对低温抗裂性有一定影响,当钢砂体积分数为6%与粒径为1.0mm时,试件的动稳定度为6 813次·mm^(-1),冻融劈裂残留强度比为93.18%,浸水马歇尔残留强度比为93.88%,同时低温弯曲应变下降为3.155×10^(-3),仍然满足《公路沥青路面施工技术规范》(JTG F40—2004)不小于3.0×10^(-3)的要求;建议采用钢砂体积分数为6%与粒径为1.0mm的SBS改性沥青混凝土用于感应加热自修复路面。

SBS modified asphalt concrete beam specimens added steel grits with pre-cut were prepared,an electromagnetic induction heating experiment was carried out,the influences of heating distance,particle size and content（volume fraction）of steel grit on the crack self-healing property and road performance of SBS modified asphalt concrete were analyzed,and thecorresponding suggestions on how to use such conductive materials were proposed.Research result shows that the smaller the heating distance is,the greater the induction heating rate is.When the induction coil is 10 mm away from the top of beam specimen,the specimen has higher heating rate and the infrared camera can capture the images easily.The steel grits are easily dispersed during the concrete preparation.The larger the size and content of steel grit are,the greater the average induction heating rate is.The top surface of the specimen has the largest average induction heating rate that reaches 1.25 ℃ ·s-1 when the volume fraction and particle size of steel grit are 6% and 1.4 mm,respectively.With the content increase of steel grit,the induction heating self-healing rate of the specimen gradually increases.The average self-healing rate can reach 89.2% when the maximum temperature of top surface of the specimen is 80℃.At the same time,the largest self-healing rate of the specimen is 96.2% when the content and particle size of steel grit are 6% and 1.0 mm,respectively.Steel grits improve the hightemperature stability of SBS modified asphalt concrete,but affect the low-temperature crack resistance.When the content and particle size of steel grit are 6%and 1.0 mm,respectively,the dynamic stability of the specimen is 6 813 times·mm-1,the residual strength ratio of freezingthawing cleavage is 93.18%,the inundation Marshall residual intensity ratio is 93.88%,and the lowtemperature bending strain only decreases to 3.155×10-3 that still meets the demand（≥3.0×10-3）of Technical Specification for Construction of Highway Asphalt Pavements（JTG F40—2004）.Therefore,the SBS modified asphalt concrete may be used for induction heating self-healing pavement when the content and particle size of steel grit are 6%and 1.0 mm,respectively.1 tab,13 figs,22 refs.