Effect of Zn/Al Layered Double Hydroxide Containing 2-Hydroxy-4-n-octoxy-benzophenone on UV Aging Resistance of Asphalt

Abstract

UV radiation is a main factor to reduce the service life of asphalt pavement due to the UV aging of asphalt binder. To obtain enhanced UV aging resistance, an organic UV absorber called 2-hydroxy-4-n-octoxy-benzophenone (HNOB) had been intercalated into an inorganic UV absorber called Zn/Al layered double hydroxide (LDH) to play a combined anti-UV role in asphalt binder. Fourier transform infrared spectroscopy revealed that HNOB anions have been intercalated into the interlayer galleries of Zn/Al-LDH containing HNOB anions (Zn/Al-HNOB − -LDH). X-ray diffraction results of Zn/Al-LDH containing<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mtext>C</mml:mtext><mml:mtext>O</mml:mtext></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>anions (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mtext>Zn/Al-</mml:mtext><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mtext>CO</mml:mtext></mml:mrow><mml:mrow><mml:mn mathvariant="normal">3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mn mathvariant="normal">2</mml:mn><mml:mo>-</mml:mo></mml:mrow></mml:msup><mml:mtext>-LDH</mml:mtext></mml:math>) and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mtext>Zn/Al-</mml:mtext><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mtext>CO</mml:mtext></mml:mrow><mml:mrow><mml:mn mathvariant="normal">3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mn mathvariant="normal">2</mml:mn><mml:mo>-</mml:mo></mml:mrow></mml:msup><mml:mtext>-LDH</mml:mtext></mml:math>/styrene-butadiene-styrene (SBS) modified asphalt disclosed that asphalt molecules entered into LDH interlayer galleries to form an expanded phase structure. UV-Vis absorbance patterns showed that Zn/Al-HNOB − -LDH has a better capacity of blocking UV light due to the synergetic effect of HNOB and Zn/Al-LDH. The chemical fractions analysis, conventional physical tests, and rheological tests of SBS modified asphalt,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mtext>Zn/Al-</mml:mtext><mml:msup><mml:mrow><mml:msub><mml:mrow><mml:mtext>CO</mml:mtext></mml:mrow><mml:mrow><mml:mn mathvariant="normal">3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:mn mathvariant="normal">2</mml:mn><mml:mo>-</mml:mo></mml:mrow></mml:msup><mml:mtext>-LDH/SBS</mml:mtext></mml:math>modified asphalt, and Zn/Al-HNOB − -LDH/SBS modified asphalt before and after UV aging testified that Zn/Al-HNOB − -LDH can improve the UV aging resistance of SBS modified asphalt more significantly.