Influence of smoke suppressant on the smoke inhibition effect and properties of different types of asphalt

The current understanding of the influence of smoke suppressants on the smoke inhibition effect and working performance of different types of asphalt is limited. In this study, portable gas detector (PGD) tests were used to investigate the influence of the smoke suppressant on different types of asphalt and the smoke purification effect. Subsequently, gas chromatography-mass spectrometry (GC-MS) was used to analyze the influence of the smoke suppressant on the volatile organic compounds (VOCs) in different types of asphalt fume, so as to compare and verify the PGD tests results. Finally, scanning electron microscopy and energy dispersive spectrometry were used to observe and analyze the influence of the smoke suppressant on the microstructure and element composition of different types of asphalt. The results show that the smoke suppressant can purify various harmful gases volatilized from different types of asphalt, but the effect and the optimal dosage of smoke suppressant are slightly different. The purification rate of the smoke suppressant for SO2 or H2S in the fumes of various asphalts can reach >70% and the NO and VOC purification rates can reach >40%. The influence of the smoke suppressant on the VOC purification rate of different asphalts detected through the GC-MS and PGD tests is similar. The smoke suppressant has little effect on the asphalt surface microstructure and on the changes in the element content in asphalt, indicating that it has no effect on the main properties of the asphalt itself. This study is helpful to further understand the relationship between smoke suppressants and the smoke inhibition effect and the working performance of different types of asphalt. Additionally, it provides basis and guidance for the development of low-smoke asphalt with a better emission reduction effect, which has a certain guiding and application significance

Study on Mechanics-Based Cracking Resistance of Semiflexible Pavement Materials

Semiflexible mixture is a composite paving material combining the advantages of both asphalt and cement concrete materials. It consists of matrix asphalt skeleton and cement mortar. Due to the different volume characters between asphalt structure and cement mortar, stress concentration always happens in this semiflexible mixture, leading to internal cracking. The objective of this study is to alleviate the internal cracking concern of the semiflexible mixture by adjusting the material components. To this end, optimal material design and numerical simulation have been conducted. Matrix asphalt structures with four different air voids were incorporated with different dosages of cement mortar. The contraction strain and expansion strain of cement mortar as well as the indirect tensile strength of matrix asphalt structure were measured. The results were input into ABAQUS for numerical simulation. The results indicated that (1) the internal stress in this semiflexible mixture is mainly determined by the contraction of cement mortar, rather than expansion; (2) larger air void of matrix asphalt structure and less volumetric variation of cement mortar reduce the internal stress; (3) once the air void of matrix asphalt structure is decided, both maximum contraction and expansion deformations of cement mortar should meet specific requirement to ensure less internal cracking. This is a practical-ready paper that provides reference for the anticracking design of semiflexible pavement

Laboratory evaluation on water-based and flexible epoxy/SiO2 nanocomposites to enhance anti-sliding effectiveness of pavement

The anti-slip (AS) layer of the cement concrete pavement (CCP) can probability decrease traffic accidents and extend the service life of the road. Epoxy resin has excellent adhesion and mechanical strength, making it possible in this field. Herein, a flexible waterborne epoxy resin (WER) without a small molecule emulsifier was synthesized by bisphenol A epoxy resin, poly (propylene glycol) diglycidyl ether (PDE), diethylenetriamine (DETA). The mechanism of the group reaction was characterized by fourier transform infrared (FTIR), and dynamic scanning calorimetry (DSC) determined the heat of curing of WER. Then, the physical properties of WER were enhanced by the silane coupling agent modified nano-silica (SCA-NS) and the composite’s water absorption rate and mechanical propriety were evaluated. Finally, the pavement performance of the AS layer was prepared and tested as well as compared with the commercial waterborne epoxy resin (CWER) and emulsified asphalt (EA). The result shows EA has low durability and adhesion strength than epoxy resin. The small molecule emulsifier and low-flexible resistance of CWER decrease water stability and anti-sliding durability of the AS layer. Due to applied nanomaterial reinforced and without small molecule emulsifiers, the WER base AS layer shows extremely high adhesion strength, water stability, and skid-resistance durability at addition 3 wt% of SCA-NS, which have a great potential for CCP

Case analysis of integrated maintenance technology for multi-dimensional rapid detection and trenchless reinforcement

China’s highway construction has moved from “construction-oriented” to the development stage of “equal attention to construction and maintenance”. The infrastructure represented by urban expressways, under heavy and complex traffic loads, is prone to a variety of diseases that take place in the middle and lower layers of pavement such as “frost boils” and “voids”, which cannot be repaired ideally with the help of conventional detection and treatment techniques. In order to solve the above problems, this paper adopts nondestructive testing plans such as ground penetrating radar and falling weight deflectometer to conduct multidimensional rapid detection of the road surface to obtain the image information and mechanical data of the road structure. Based on the improved calculation method, the pavement disease area, depth and type can be effectively judged. Combined with the observation of water level, the polymer grouting reinforcement plan is designed to eliminate the problems in the middle and lower layers of the road surface. It can effectively reduce the incidence of diseases in the upper layer of the sidewalk, and significantly improve the efficiency and service level of the sidewalk

Research on Application Effect of Mixconverter in Cement Concrete Pavement

In order to improve the strength of cement concrete pavement and reduce pavement cracking, the application effect of the hydration reaction enhancer Mixconverter in cement concrete pavement was studied by testing the compressive strength, bending strength, crack resistance and chloride ion permeability of concrete indoors. The test results show that the addition of Mixconverter to concrete can significantly improve the compressive and flexural strength of concrete, effectively prevent the expansion of plastic shrinkage and cracking of concrete, and significantly reduce the chloride ion diffusion coefficient. Finally, the test road pavement further proves the improvement effect of Mixconverter on concrete strength and cracking

A study of film thickness and hydrodynamic entrance length in liquid laminar film flow along a vertical tube

The liquid film thickness and hydrodynamic entrance length in a vertical tube was studied experimentally and numerically. Measurements using distilled water, 30 wt % MEA and 40 wt % sugar solutions were carried out to investigate the effects of liquid flow rate on the formation of the liquid film. The experimental results validate the new Navier-Stokes based equation in cylindrical coordinates (Eq. 16) and the volume of fluid (VOF) model giving a competitively high prediction of the liquid film thickness especially in the low Reynolds number region. In addition, a new empiricalmodel and an improved minimal surface model have been first proposed for calculation of the hydrodynamic entrance length, with a relatively reasonable average absolute relative deviation (AARD) of 3.03% and 6.83%, respectively. Furthermore, the effects of the hydrodynamic entry length on the gas–liquid interfacial area calculated by the improved minimal surface model were comprehensively studied, and can be ignored if the ratio of the liquid film length (y) and the hydrodynamic entrance length (kE) is lower than 10. However, it should be noted that the hydrodynamic entrance length cannot be ignored in packed columns in which the liquid flow is very complex due to the packings with different structures and materials.submittedVersionThis is the pre-peer reviewed version of an article, which has been published in final form at https://doi.org/10.1002/aic.16081. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving

Study on the Performance of the Physical Foaming Warm-mix Recycled Asphalt Mixture

In order to evaluate the performance of the physical foaming warm-mix recycled asphalt mixture (WRAM), the hot mix plant recycling technology was adopted to develop AC-20 hot-mix recycled asphalt mixture (HRAM) and the WRAM of different reclaimed asphalt pavement (RAP) contents. The high temperature stability, water stability and low temperature crack resistance performance of the reclaimed asphalt pavement were evaluated. The results indicate that the physical foaming WRAM feature better high temperature stability, water stability and low temperature crack resistance compared to those of HRAM. With the increase in RAP contents, the high temperature stability of the physical foaming WRAM and HRAM rises notably but the water stability and low temperature crack resistance performance continues to drop

Design method of the mix ratio of hot mix plant recycled asphalt mixture containing high mixture content

This paper mainly used the Superpave and the Marshall design methods to design the mix ratio of the hot mix plant recycled asphalt mixture. The road performance of AC-20, SUP-20 with 30% RAP content and AC-20 with 50% RAP content was studied to evaluate the water stability and high temperature stability and low temperature crack resistance of the recycled asphalt mixture. Research shows that the road performance of AC-20 mixed with 50% RAP content meets the technical requirements of the same type of asphalt mixture. It is recommended to use the Marshall design method for hot mix plant recycled asphalt mixture design