Investigation into engineering properties and strength mechanism of grouted macadam composite materials

Abstract

To further understand engineering properties of grouted macadam composite materials (GMCM) used as a surfacing layer in pavement, the mechanical properties and durability characteristics of GMCM were evaluated, and the relevant strength mechanisms were investigated at the micro level. Results indicate that GMCM has better high-temperature stability, fatigue performance and moisture stability than that of conventional asphalt mix, while it shows an acceptable decrease in low-temperature crack resistance due to the relative brittleness of hardened cement paste. The hardened cement paste also generates a spatial network crystalline lattice in asphalt mix skeleton to form a three-dimensional integral coagulation-crystalloid structure. This facilitates the asphalt mix skeleton and hardened cement paste to bear loads in unison and increase durability of the GMCM. Further, the fibre-like hydrated products of fresh cement slurry on the bitumen film surface increase the interfacial strength between bitumen and hardened cement paste due to toughening and bridging effects, which plays an important role to enhance mechanical properties and durability of GMCM. Finally, GMCM strength is from the internal friction of asphalt mix skeleton, the network structure of hardened cement paste and the adhesion between porous asphalt mix and hardened cement paste. It is concluded that GMCM can better meet the requirements of mechanical properties and durability characteristics than the conventional asphalt mix.

Keywords::

• grouted macadam composite materials
• engineering properties
• asphalt mix skeleton
• cement slurry
• strength mechanism

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Authors would like to thank the financial support from National Natural Science Foundation of China [grant number 51378264], [grant number 51108237] and Jiangsu Provincial Department of Education for the Qing Lan Project [grant number 2014-23] and Jiangsu Province College Graduate Students' Scientific Research and Innovation Program [grant number SJLX-0402].