Zhanyong Yao

Performance of Composite Modified Asphalt with Trinidad Lake Asphalt used as Waterproofing Material for Bridge Deck Pavement

Performance of composite modified asphalt with Trinidad Lake Asphalt (TLA) used as waterproofing material for bridge deck pavement was studied through the shear test, pull-out test, and water permeability test. The results showed that shear strength at 20°C of composite modified asphalt with TLA was affected by the material dosage and the optimum dosage was 1.2 kg/m2. Shear strength at 20°C of composite modified asphalt with TLA increased with the increase of TLA content and then decreased with the further increase of TLA content. However, the shear strength at 50°C shows different results. Based on shear strength at 20°C, the optimum TLA content was 20 % by total weight of composite modified asphalt. Bond strength at 20°C of composite modified asphalt with TLA was very close to that of styrene-butadiene-styrene (SBS) modified asphalt but the bond strength at 50°C of composite-modified asphalt with TLA was 47 % higher than that of SBS modified asphalt. Both composite modified asphalts with TLA and with SBS modified asphalt met the impermeability requirement. Composite modified asphalt with TLA could be used as waterproofing material for bridge deck pavement for better performance.

Piezoresistive Characterization of Polyethylene Terephthalate–Graphite Composite

This study investigated the mechanical properties as well as electrical resistivity and piezoresistivity of the polyethylene terephthalate (PET)–graphite composite. The effects of graphite content, loading type, and loading rate on the performance of PET–graphite composite were investigated. Test results showed that the compressive and flexural strengths of the composite decreased rapidly as the graphite content was beyond 12 %. The electrical resistivity of the composite decreased from 3.5 × 108 Ω · cm to 2.2 × 103 Ω · cm as the graphite contents increased from 8 % to 12 %. The graphite content for the conductive percolation threshold of the PET–graphite composite was determined to be 13 %. The PET–graphite composite was sensitive to low compressive stress. When the compressive stress reached 0.7 MPa, the fractional change in the resistivity could reach 10.5 %. The piezoresistivity of the PET–graphite composite was significantly influenced by the loading rates. The field test indicated that the composite was able to detect the traffic effectively.

Mix Proportion Design and Mechanical Properties of Recycled PET Concrete

The mix proportion and mechanical properties of polyethylene terephthalate (PET) concrete were studied by orthogonal test. PET concrete was produced by mixing melted PET with aggregate and mineral admixtures. The effects of several factors on the properties of PET concrete were investigated. These factors included: (1) coarse aggregate type, (2) mineral materials, (3) PET and mineral/aggregate (PETAM/AG) ratio, (4) sand ratio, (5) PET/mineral (PET/MA) ratio, and (6) maximum particle size of coarse aggregate. The results showed that the most important factor was PETAM/AG, followed by sand ratio and PET/MA. Samples with 10 mm coarse aggregate had the highest compressive strength of 36 MPa. The compressive strength decreased 8.6 and 37 % as the coarse aggregate maximum particle sizes changed from 10 to 4.75 and 13 mm, respectively. There was no significant difference in flexural strength when the sand ratio changed from 35 to 68 %. The strength of PET concrete with basalt was higher than that of concrete with limestone. The concrete containing fly ash and 5 % talc had the highest strength followed by concrete with fly ash, Portland cement (PC), fly ash with 5 % asphalt, without any mineral. The best mix proportion of PET concrete was PETAM/AG of 1:3, sand ratio of 35 % and PET/fly ash of 2:1.

Mix Proportion Design and Mechanical Properties of Recycled Polyethylene Terephthalate Concrete

The mix proportion and mechanical property of polyethylene terephthalate (PET) concrete was studied by orthogonal test and mix proportion design. Different limestone, basalt aggregate and mineral were used to mix with melted PET to produce PET concrete. The effects of mineral materials, PET, and mineral/aggregate ratio (PETWA/AG), sand ratio, PET/mineral ratio (PET/MA), and materials of coarse aggregate on PET concrete mechanical property were analyzed. The results showed that the most important factor was PETWA/AG and then sand ratio and PET/MA. Basalt was better than limestone as coarse aggregate in PET concrete. From high to low compression strength sequence of PET concrete mixed with different mineral was fly ash with 5% talc, only mixed fly ash or Portland cement (PC), mixed fly ash with 5% asphalt, without any mineral. The best mix proportion of PET concrete was PETWA/AG=1/3, sand ratio=35%, and PET/fly ash=2~1.

Vibration Propagation of Dynamic Compaction in Widening Highway Foundations

Dynamic compaction is an economical and effective method to improve foundation conditions. When widening the highway foundation, it is unclear whether the law of dynamic compaction vibration affects the original subgrade and structure, which restricts the use of dynamic compaction technology in the highway foundation-broaden project. By using free lossless audio codec (FLAC) 3-D numerical calculation software, a dynamic compaction vibration finite difference model was built to analyze the dynamic compaction vibration propagation law of the roadside foundation in the subgrade and pavement structure. At the same time, the vibration acceleration of the key points and the rammer subsoil dynamic pressure value were made as double assessment indicators. The dynamic compaction vibration response of the subgrade and comprehensive evaluation of the foundation reinforcement effect with different parameters were obtained. Through the indoor model test, the reliability of the numerical analysis was verified. The tamping energy of 1500 KN m, drop height of 6 m (corresponding rammer weight of 25T) and rammer diameter of 1.5 m or 2 m were used in the test. The result showed that a good foundation reinforcement effect can be reached as well as the minimal vibration effects on the surrounding environment. Compared with flat terrain, the dynamic compaction vibration acceleration attenuation at embankment toe is more significant. For all, the pavement structure vibration accelerations tended to be a rapid decay. The medial maximum acceleration reached to 3.9 m/s². The compaction vibrations acceleration of road base and subbase does not significantly change, which both are less than the surface layer.