جستجوی مقالات مرتبط با کلیدواژه « linear amplitude sweep » در نشریات گروه « عمران »

Today, with the expansion of the road network and the increase in construction and maintenance costs of pavements, using additives in bitumen has become a popular method to improve asphalt performance. Various polymeric additives are widely used additives in bitumen and asphalt mixture. This paper investigates the effects of 2, 4, and 6 wt% of Styrene-Ethylene/Propylene-Styrene (SEPS) polymer on the bitumen's behavior. In this regard, linear amplitude sweep (LAS) and time sweep (TS) tests have been used to evaluate the fatigue characteristics of modified bitumen. In addition to the common method of estimating fatigue life in the LAS test, the pseudo-stress method was also used, and the results of three techniques were compared. As a result, using SEPS in bitumen reduces the fatigue life by 12% in the sample containing 2% of SEPS; however, fatigue life increased to 27.9 times greater than virgin bitumen by increasing the percentage of SEPS. The results of LAS and TS tests show a significant difference compared to each other. The LAS test is a suitable method to check the fatigue characteristics of bitumen due to the shorter test time. According to the pseudo-stress method results, the fatigue life of the samples containing 2, 4, and 6 wt% of SEPS are 0.75, 2.5, and 15.8 times greater than the virgin bitumen sample.

Applying the tire rubber powder as an additive of bitumen has been one of the considerable topics for the researches. The use of the recycled tire rubber as a measure for protecting the environment moreover the considerable improvement in the bitumen performance and cheaper than the other polymers make the topic more important. In this research, in addition to the tire rubber powder, it has been tried to use the asphalt recycled from reclaimed asphalt pavement as an alternative for replacing bitumen. So, a sample of rubber modified bitumen was prepared and combined with different percentages of the recycled asphalt and tested. The aim of the tests has been examining the rutting and fatigue performance of the bituminous binder by the newer methods such as multiple stress creep recovery, temperature and frequency sweep and linear amplitude sweep. The test results showed that adding 15 to 25 percent of the recycled asphalt to the base rubber bitumen has a considerable effect in increasing complex shear modulus and decreasing the phase angle. So, the recycled asphalt improved the elastic behavior of the rubber bitumen and increased rutting resistance of the bitumen. But, the fatigue resistance of the rubber bitumen was decreased.