Mingliang Xing

Investigation on the Properties of Asphalt Mixtures Containing Antifreeze Fillers

AbstractTo investigate the properties of antifreeze asphalt mixtures (AFAC), the dense-graded and gap-graded asphalt mixtures, AC-13 and SMA-13, containing 2, 4, 5, 6, and 4 % by weight and 5, 6, 7, and 8 % by weight antifreeze filler, respectively, were used in this paper. In the experiments, Marshall, rutting, bending beam, and immersion Marshall tests were used to study the engineering performances of AFAC. In addition, a conductivity test was carried out to evaluate the salt releasing law under static state condition. Results show that the properties of AFAC are affected by the gradation composition and content of antifreeze filler. It is suggested that the content of antifreeze filler is 3∼6% by weight according to the Marshall test. The composition type of asphalt mixture is an important factor in AFAC because the durability of SMA-13 is worse than that of AC-13. Moreover, the salt releasing process is divided into three steps based on the conductivity test.

Influence of thickeners on cement paste structure and performance of engineered cementitious composites

Hydroxypropyl methylcellulose (HPMC) and amphoteric polyacrylamide (ACPAM) were respectively used to prepare engineered cementitious composite (ECC) which exhibits strain-hardening behavior under uniaxial tension. The connections between cement paste structure and the performance of the composite in fresh and hardened state were investigated, aiming at achieving the desirable workability at a given solids concentration. The experimental results of viscosity and microstructure of cement pastes show that the intimate connections between flocculation groups lead to the growing increase in viscosity. The results of deformability and fiber dispersion demonstrate that fiber dispersion coefficient is a comprehensive index which can reflect the performance of deformability as well as uniformity. And the desirable fresh mixture can be achieved by optimizing the viscosity of cement paste. At last, the ductile strain-hardening performance of the ECC prepared with HPMC or ACPAM was investigated through uniaxial tensile test.