A Study on High and Low Temperature Rheological Properties and Oil Corrosion Resistance of Epoxy Resin/SBS Composite Modified Bitumen

In order to investigate the high and low temperature rheological properties and fuel corrosion resistance of epoxy resin on SBS modified asphalt, epoxy resin/SBS composite modified asphalt (ER/SBS) was prepared by high-speed shear. Moreover, composite modified bitumen with different proportions were designed based on the uniform design method and the basic performance index test was performed. The optimal composite mixing ratio of the ER and SBS modifier in composite modified asphalt (2.3% and 3.8%, respectively) was determined. Temperature scanning and a multiple stress creep test (MSCR) on ER/SBS composite modified asphalt with different ER content before and after oil corrosion was carried out using a dynamic shear rheometer (DSR). In addition, the high temperature rheological properties of different ER contents and composite modified asphalt after oil corrosion were evaluated by combing DSR measurements with the test data. The creep stiffness (S) and creep rate (m) indexes were obtained by a bending rheometer (BBR), and the effect of ER on the low-temperature rheological properties of SBS modified bitumen was investigated. The influence of the modifier incorporation on the micromorphology of asphalt and the change of micromorphology of asphalt after oil corrosion were analyzed by fluorescence microscopy. The test results show that the incorporation of 2.3% ER and 3.8% SBS can effectively improve the high temperature performance of SBS modified asphalt under the premise of cost saving. Moreover, the composite modified asphalt doped with ER can effectively improve the resistance of SBS modified asphalt to fuel corrosion at high temperatures, and the greatest improvement in the oil corrosion resistance of composite modified asphalt is observed at the ER content of 2.3%.

Static test research on steel bridge deck pavement structures paved by high-content hybrid fibre polymer concrete

Steel bridge deck pavement has always been a key and difficult point in the construction of long-span bridges. In practical engineering, common paving material is asphalt, and serious damage is caused on the pavement layer in the early stage. In this study, a high-performance high-content hybrid fibre polymer concrete was used as the paving material. A test was conducted on the small beam of the composite structure formed by the pavement layer and steel plate, and a positive/negative bending moment test was conducted to analyse the stiffness and bearing capacity of the composite structure. As revealed in the research results, the flexural and tensile stiffness of the structure and the bearing capacity of the composite structure showed superior performance, increased significantly with the pavement thickness, but increased slowly after the pavement thickness exceeded 80 mm and the increase in thickness contributed little to the bearing capacity. Under the simulated action of a positive/negative bending moment, the pavement layer still exhibited certain ductile failure features when the structure was bearing an ultimate load. This proves that high-content hybrid fibre polymer concrete exhibits suitable mechanical properties for steel bridge deck pavement.

Effect of Carbon Black on Rutting and Fatigue Performance of Asphalt

As an additive to improve the performance of asphalt binder, tire pyrolysis carbon black is gradually being used in road engineering, but the effect of carbon black (CB) with different particle sizes on asphalt modification remains to be further studied. In this study, three kinds of particle sizes and three kinds of contents of CB were used to modify asphalt, and different tests were conducted to research the high temperature performance and fatigue resistance of carbon black modified asphalt binder. It is found that the addition of CB can enhance the rutting resistance and medium temperature fatigue performance of virgin asphalt binder in general. However, for CB of 270 μm and 2.6 μm, its addition under certain contents lead to the decrease of high temperature performance and fatigue performance of the asphalt binder. For aged asphalt, the addition of CB decreases the rutting resistance and improves the fatigue resistance. The recommended content and particle size of CB are 2% and 2.6 μm. This study refines the complex effects of CB on asphalt properties, providing a reference for determining the size and content of CB in asphalt modification.

Synergistic Effects of Ladder and Cage Structured Phosphorus-Containing POSS with Tetrabutyl Titanate on Flame Retardancy of Vinyl Epoxy Resins

The cage and ladder structured phosphorus-containing polyhedral oligomeric silsesquioxanes (DOPO-POSS) have been synthesized through the hydrolytic condensation of 9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide (DOPO)-vinyl triethoxysilane (VTES). The unique ladder and cage–ladder structured components in DOPO-POSS endowed it with good solubility in vinyl epoxy resin (VE), and it was used with tetrabutyl titanate (TBT) to construct a phosphorus-silicon-titanium synergy system for the flame retardation of VE. Thermal stabilities, mechanical properties, and flame retardancy of the resultant VE composites were investigated by thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), three-point bending tests, limiting oxygen index (LOI) measurement, and cone calorimetry. The experimental results showed that with the addition of only 4 wt% DOPO-POSS and 0.5 wt% TBT, the limiting oxygen index value (LOI) increased from 19.5 of pure VE to 24.2. With the addition of DOPO-POSS and TBT, the peak heat release rate (PHRR), total heat release (THR), smoke production rate (SPR), and total smoke production (TSP) were decreased significantly compared to VE-0. In addition, the VE composites showed improved thermal stabilities and mechanical properties comparable to that of the VE-0. The investigations on pyrolysis volatiles of cured VE further revealed that DOPO-POSS and TBT exerted flame retardant effects in gas phase. The results of char residue of the VE composites by SEM and XPS showed that TBT and DOPO-POSS can accelerate the char formation during the combustion, forming an interior char layer with the honeycomb cavity structure and dense exterior char layer, making the char strong with the formation of Si-O-Ti and Ti-O-P structures.

Efficient Adsorption of Dyes Using Polyethyleneimine-Modified NH2-MIL-101(Al) and its Sustainable Application as a Flame Retardant for an Epoxy Resin

Metal-organic frameworks (MOFs) exhibit highly designable properties and have been used in wide applications. To further improve their performance, the modification of MOFs is an effective method. However, the modification process is usually complicated. Besides, the sustainable use of MOFs is difficult to achieve due to the complicated recycling treatment. Herein, we designed a polyethyleneimine (PEI)-modified NH₂-MIL-101(Al) composite (PEI@NH₂-MIL-101(Al)). This composite showed excellent dye removal performance of methyl orange (MO, 89.4%) and Direct Red 80 (DR80, 99.8%). Remarkably, the dye removal application of PEI@NH₂-MIL-101(Al) also acted as a modification process toward flame retardant application. Thus, the dye-adsorbed PEI@NH₂-MIL-101(Al) composite (MO-PEI@NH₂-MIL-101(Al) and DR80-PEI@NH₂-MIL-101(Al)) was sustainably used as an effective flame retardant for an epoxy resin (EP) at low additions (4.0 wt %). The limiting oxygen values of EP/MO-PEI@NH₂-MIL-101(Al) and EP/DR80-PEI@NH₂-MIL-101(Al) increased to 26.5 and 26.7%, respectively. The heat release and the smoke production of dyes-PEI@NH₂-MIL-101(Al)/EP were greatly reduced compared with those of EP. This strategy provides a simple and effective modification method for MOFs. Meanwhile, the modified MOF composite can achieve sustainable application, giving full play to the advantages of MOFs.