Research On Design And Properties Of High Viscosity Modified Asphalt With SBS Compound Polyphosphoric Acid

The researchs and applications of acidic asphalt modifiers represented by polyphosphoric acid have begun abroad in the early 1990s.Since the 21st century,polyphosphoric acid modification has gradually become an important asphalt modification method in China.Polyphosphoric acid modified asphalt has the characteristics of excellent high temperature performance and high viscosity.This article mainly studies polyphosphoric acid composite SBS high-viscosity modified asphalt with high dynamic viscosity,low construction viscosity,excellent high-temperature rutting resistance,good low-temperature performance,and excellent storage stability。First of all,in order to reduce the construction viscosity of high-viscosity asphalt with polyphosphoric acid composite SBS,polyethylene wax is cited in this paper for the three-factor orthogonal experimental design of polyethylene wax,rubber powder and SBS;on the basis of a good asphalt performance,the high-viscosity asphalt with a construction viscosity of≤2.5 Pa.s was selected as the polyphosphoric acid composite modified parent asphalt.The formula of the parent high viscosity asphalt（HVA-4）is 0.75%polyethylene wax,5.5%SBS,10%40 mesh rubber powder,1%crosslinking agent,5%aromatic hydrocarbon oil,3%Terpene resin.Then on the basis of preparing HVA-4,two sets of polyphosphoric acid composite SBS high-viscosity modified asphalt（HVA-0.5%,HVA-1%）with different amounts of polyphosphoric acid（0.5%,1%）were prepared.HVA-4,HVA-0.5%,HVA-1%,domestic HVA high-viscosity asphalt and Japan TPS high-viscosity modified asphalt were used to compare asphalt performance.The temperature scanning and MSCR test results show that adding 1%polyphosphoric acid can improve a high-temperature grade and modulus grade of high-viscosity asphalt;PG grade of HVA-0.5%is 88℃,at 88℃it belongs to extremely high modulus grade,domestically produced HVA and TPS high-viscosity asphalts belong to high modulus grade.after the isolation of HVA-0.5%,the unrecoverable creep compliance J_nr3.2is incred by 12.668%compared with that before isolation,which is 2.7%lower than that of domestic HVA J_nr3.2,and 2.1%higher than TPS;the recoverable ratio R_3.2Reduced by10.153%,which is 7.4%lower than Jnr3.2 of domestic HVA and 4.3%higher than TPS;combining the changes of J_nr3.2and R_3.2,it can be concluded that HVA-0.5%storage stability is similar to TPS and superior to domestic HVA.The optimal mixing temperature determined by the viscosity temperature curve fitted by the designed zero-shear temperature is 180℃,and the compaction temperature is 172℃,which is about 10℃lower than the temperature of ordinary high-viscosity asphalt.As a result,when the content of polyphosphoric acid is0.5%,the comprehensive performance of asphalt is the best,the dynamic viscosity at 60℃>120000Pa.s,and the rotational viscosity at 135℃is only 2.87Pa.s.Finally,the road performance of the self-made polyphosphoric acid composite SBS high-viscosity asphalt was verified.Three types of OGFC-13 mixtures were prepared by using HVA-0.5%,domestic HVA and TPS.The road performance test results show that the dynamic stability of the self-made high-viscosity asphalt mixture is up to 8536 times/mm,which is1300 times/mm higher than the OGFC-13 made by TPS;low temperature bending test results shows The difference is slight;the scattering losses of three OGFC-13 made by HVA-0.5%,TPS,domestic HVA are 13.6%,18.7%,19.3%;After a freeze-thaw test on 13℃,the ratio of split strength to split strength was 82.14%,87.27%,and 80.95%respectively;the results showed that the self-made high-viscosity asphalt mixture had the best water stability under water conditions.The water stability of self-made high-viscosity bitumen is slightly inferior to TPS under melting conditions and better than domestic HVA.