Laboratory study of the effect of long-term aging and temperature on resilient modulus of dense graded asphalt concrete with lime kiln dust

Abstract

The flexible pavements are highly vulnerable to surface damage due to an increase in temperature, excessive load, moisture and aging of asphalt mixes. They should have high engineering and structural performance to have a maximum service life. Resilient Modulus (Mr) is the stiffness or a measure of cohesion of asphalt concrete (AC) mixture. It is an important parameter in pavement design and plays a vital role in flexible pavement durability. Stiffness of an AC mixture is varying with temperature and long-term field condition. Previous researches proved that Lime Kiln Dust (LKD) performs well as a mineral filler and moisture damage reducing agent in Dense Graded Asphalt (DGA) mixture. This paper highlights how LKD effects on the stiffness of DGA mixes with the variation of temperature and aging. Mr is measured by using the indirect tensile method under aged and unaged conditions at 20 oC and 40 0C temperatures. The study was done on DGA 10 and DGA14 mixtures with hydrated lime (HL), LKD and no additive (control mix). SHRP long-term oven aging (LTOA) was used for aging specimens to represent 15 years of field aging in a Wet-No-Freeze climate and 7 years in a Dry-Freeze climate. This research found that LKD and HL based mixtures perform almost the same when considering the effect of aging and temperature on Mr. Stiffness of all mixtures decrease when temperature increases and increase with aging. LKD provides more stiffness to DGA mixtures than HL under long term aging condition. LKD based mixtures show minimum stiffness reduction with the temperature increasing. Therefore, it can be concluded that LKD is an excellent mineral filler that can be used as a substitute for HL to enhance the performance of DGA mixture in terms of high temperature and excessive loading.