Review of emulsified asphalt modification mechanisms and performance influencing factors

In recent years,with the improvement of the requirements of road performance,modified emulsified asphalts with better performance has gradually replaced the emulsified asphalt and become the primary material for road maintenance.This paper introduces the modified emulsified asphalt materials commonly used in pavement maintenance projects,definitions and modified mechanisms of polymerized styrene butadiene rubber(SBR)modified emulsified asphalt,styrene butadiene styrene block polymer(SBS)modified emulsified asphalt and waterborne epoxy resin(WER)modified emulsified asphalt are summarized.The analysis focused on comparing the effects of modifiers,preparation process,auxiliary additives,and other factors on the performance of modified emulsified asphalt.In this paper,it is considered that the greatest impact on the performance of emulsified asphalt is the modifier,emulsifier mainly affects the speed of breaking the emulsion,stabilizers on the basic performance of emulsified asphalt evaporative residue is small;and when the modifier is distributed in the asphalt in a network,the dosage at this time is the recommended optimum dosage.Finally,this study recommends that in the future,the polymer-asphalt compatibility can be improved through composite modification,chemical grafting and other methods to continue to develop broader applicability and better performance of modified emulsified asphalt.

Mixing ratio design of emulsified asphalt cold recycled mixture based on gyratory compaction molding

In order to study the application of gyratory compaction molding method in emulsified asphalt cold recycled mixture and optimize the relevant technical parameters, the study was carried out according to splitting strength, stability and water stability test;the design of the experiment involved changing gyration number, emulsified asphalt and water content, molded specimen temperature and other factors to analyze the volume parameters, mechanical properties and water stability. The results show that both the maximum dry density and dry and wet splitting strength ratio(DWSSR) of emulsified asphalt cold reclaimed mixture are improved by the rotary compacting method, while the porosity and the optimal dosage of water are reduced. Furthermore, with the increase of compaction times, the porosity and splitting strength index both change exponentially. DWSSR and porosity are consistent with quadratic functions. The use of gyratory compaction for 70 times at 25 °C and the optimum dosage of emulsified asphalt can be determined based on the splitting strength ratio. The high-temperature stability and water damage resistance of the pavement can be improved by the use of rotary compacting method effectively, and the early strength and road performance are higher than the regulatory requirements.

Fe_(3)O_(4) nanoparticles encapsulated in graphitized and inplane porous carbon nanocages derived from emulsified asphalt for a high-performance lithium-ion battery anode

In this work,C@Fe_(3)O_(4) composites were prepared through a typical template method with emulsified asphalt as carbon source,ammonium ferric citrate as transition metal oxide precursor,and NaCl as template.As an anode for lithium-ion batteries,the optimized C@Fe_(3)O_(4)-1:2 composite exhibits an excellent reversible capacity of 856.6 mA·h·g^(-1)after 100 cycles at 0.1A·g^(-1)and a high capacity of 531.1mA·h·g^(-1)after 300 cycles at 1 A·g^(-1),much better than those of bulk carbon/Fe_(3)O_(4) prepared without NaCl.Such remarkable cycling performance mainly benefits from its well-designed structure:Fe_(3)O_(4) nanoparticles generated from ammonium ferric citrate during pyrolysis are homogenously encapsulated in graphitized and in-plane porous carbon nanocages derived from petroleum asphalt.The carbon nanocages not only improve the conductivity of Fe_(3)O_(4),but also suppress the volume expansion of FesO4 effectively during the charge discharge cycle,thus delivering a robust electrochemical stability.This work realizes the high value-added utilization of low-cost petroleum asphalt,and can be extended to application of other transition-metal oxides-based anodes.

Viscoelastic deformation behavior of cement and emulsified asphalt mortar in China railway track system I prefabricated slab track

Under repeated train-induced loads, cement and emulsified asphalt mortar(CA mortar) as a viscoelastic material has a time-dependent deformation, part of which is irreversible. This could lead to debonding between the mortar layer and the track slab. Based on the theory of viscoelasticity and the analytical method of the time hardening law(THL), the viscoelastic deformation behavior of CA mortar was studied. Using ABAQUS, we established a solid model of China railway track system(CRTS) Ⅰ prefabricated slab track, with CA mortar at different initial Young’s moduli under cyclic loading corresponding to the influence of actual train loads. The results reveal that the fitted parameters of the THL for CA mortar are suitable for describing its viscoelastic deformation. As the initial Young’s modulus increases, the strain difference before and after cyclic loading gradually decreases, and the displacement difference increases from 0.2 mm to 0.6 mm. The deformation mainly occurs at the end of a mortar layer with longitudinal distribution of about 2.5 times the fasteners’ spacing. It follows that the viscoelastic performance of CA mortar is one of the most important reasons that cause debonding underneath the track slab. Therefore, we suggest that the adverse effects of viscoelastic behavior of CA mortar should be considered when researching such deformation and damage.

Laboratory investigation of emulsified asphalt binder modified with wood-derived nano-cellulose and nano paper-cellulose

Emulsified asphalt is the primary material for preventive maintenance and cold-mix paving,but its low cohesive strength and poor mechanical properties limit its wide application,even with polymer modification.In this study,Styrene-Butadiene Rubber(SBR)emulsified asphalt was modified with nano-cellulose materials,namely nano paper-cellulose(NPC)and wood-derived nano-cellulose(WDC),to improve its properties.A novel preparation method of nano-cellulose solution was developed,including blending,ultrasonic stirring,and centrifugal treatment.Four types of nano-cellulose solution(0.5%NPC,0.5%,1.0%,and 1.5%WDC by weight of water)were selected.The microscopy analysis indicated that 0.5%WDC emulsion had a smaller particle size than 1.5%WDC emulsion.The rheology test indicated that WDC modified residue improved rutting resistance with the increased solution dosage due to the cross-linking effect,but its creep-and-recovery performance was worse than that of SBR emulsion residue.The NPC modified binder had a higher rutting factor than WDC modified binder at the same dosage after short-term aging.In addition,1.0%WDC could be regarded as the optimal dosage in terms of fatigue and low-temperature performance.Furthermore,Fourier Transform Infrared Spectroscopy(FTIR)results showed that 0.5%NPC modified residue performed better in long-term aging resistance compared with 0.5%WDC modified asphalt.

NOVEL SYNTHETIC METHOD OF LINGNINAMINETYPE ASPHALT EMULSIFIER

The slurry scaling with cationic emulsified asphalt, which is a new technique in highway construction, is rapidly extended at home and abroad. The technique should apply an excellent slow set cationic cmulsincr. Now, slow set emulsificrs are ligninamines which are synthesized by trimethylamine-epichlorohydrin route. Owing to high price and unstable quality, the extending of slurry sealing technique is affected seriously. We prepare the ligninaminc by a novel synthetic method. By the novel method, the cost of production is reduced by more than 30%, and the products have stable quality, high emulsifying function and broad adaptability for various asphalts. The novel synthetic method uses soda lignin, secondary amines and inexpensive aminating assistants as raw materials. The technological process of the method may use either one or two-step process, and the technological condition arc uncomplicated and easy to master.

Preparation of fluidized catalytic cracking slurry oil-in-water emulsion as anti-collapse agent for drilling fluids

Fluidized catalytic cracking slurry oil-in-water emulsion(FCCSE)was prepared by using interfacial complexes generation method that was simple and versatile.The critical factors influencing the sample preparation process were optimized,for instance,the optimum value of the mixed hydrophile-lipophile balance of compound emulsifier was 11.36,the content of compound emulsifier was 4 wt%,the emulsification temperature was 75
C,the agitation speed was 200 rpm,and the emulsification time was 30e45 min.The performance as a drilling fluid additive was also investigated with respect to rheological properties,filtration loss and inhibition of FCCSE.Experimental results showed that FCCSE was favorable to inhibiting clay expansion and dispersion and reducing fluid loss.Furthermore,it had good compatibility with other additives and did not affect the rheological properties of drilling fluids.FCCSE exhibited better performance than the available emulsified asphalt.It has a promising application as anti-collapse agent in petroleum and natural gas drilling.