Effect of Ageing on Self-Healing Properties of Asphalt Concrete Containing Calcium Alginate/Attapulgite Composite Capsules

Abstract

Calcium alginate capsules within asphalt concrete can gradually release interior asphalt rejuvenator under cyclic loading to repair micro cracks and rejuvenate aged asphalt in-situ. However, asphalt pavement will become aged due to environmental and traffic factors during the service period. In view of this, this paper investigated the effect of ageing on the healing properties of asphalt concrete containing calcium alginate/attapulgite composite capsules under cyclic loading. The capsules were fabricated using the orifice-bath method and the morphological structure, mechanical strength, thermal stability, oil release ratios and healing levels of capsules in fresh, short-term ageing and long-term ageing asphalt concrete were explored. The results indicated that the different ageing treatments would not damage the multi-chamber structure nor decrease the mechanical strength of capsules but would induce the capsules release oil prematurely. The premature oil released from capsules in turn can offset the ageing effect owing to ageing treatment. The short-term ageing and long-term ageing plain asphalt mixtures gained strength recovery ratios of 39.3% and 34.2% after 64,000 cycles of compression loading, while the strength recovery ratios of short-term ageing and long-term ageing asphalt mixtures containing capsules were 63.5% and 54.8%, respectively.

Self-Healing Performance of Asphalt Concrete with Ca-Alginate Capsules under Low Service Temperature Conditions

“…The improvement in the level of healing was attributed to the collective action of more of the rejuvenator being released and an enhanced healing temperature. In the previous literature [ 22 , 23 , 27 , 29 , 33 , 46 , 47 ], when the test temperature was 20 °C, the asphalt concrete with the calcium alginate capsules all obtained higher healing ratios than plain asphalt concrete (without capsules).…”

“…Therefore, the Ca alginate capsules must withstand the mechanical action created in the production period of the asphalt concrete. Practice has shown that the mechanical strength of the capsules used for bituminous mixtures must be greater than 10 N [ 33 , 34 ]. Figure 8 presents the compressive strength of the capsules after specific temperature treatment.…”

“…Sunflower oil can supply light component for aged asphalt and help it restore its original property. Besides, sunflower oil has a distinct peak at 1745 cm −1 , while virgin asphalt has no absorption peak between 1700–1750 cm −1 [ 23 , 31 , 33 ]. Therefore, according to FTIR spectra, this characteristic peak can be used to evaluate the healing agent release ratio of the capsules in bituminous concrete after cyclic loading.…”

“…In this work, the chemical evaluation of the healing agents released by the capsules in the asphalt mixtures was performed by FTIR spectroscopy (Thermo Fisher Scientific, Nicolet 6700, Waltham, CT, USA). Sunflower oil has a peak at 1745 cm −1 with a peak area lined with the oil content in asphalt, while asphalt has no peak in this characteristic range [ 23 , 33 ]. Figure 4 a shows the infrared spectra of the oil and asphalt used in this study.…”

Self-Healing Mechanical Properties of Selected Roofing Felts

“…The authors of [ 40 ] present SH in microcapsule asphalt; [ 41 ] presents SH in asphalt due to the microwave heating of the pavement. The durability and aging of self-healed asphalt concrete is discussed in [ 42 ], and the performance of SH in porous asphalt is presented in [ 43 ]. Modeling SH materials is another group of articles that could be distinguished.…”