Rajan Choudhary

Characterization of Fly Ash Bituminous Concrete Mixes

Fly ashes were collected from 14 thermal power stations located in different parts of India and were characterized using simple tests like fineness modulus, specific gravity, Rigden voids, German filler test and methylene blue value test, and advanced tests like X-ray diffractometer, scanning electron microscope, and chemical analysis. These fly ashes were divided into four groups based on the above tests and then used as filler in bituminous concrete (BC) mixes. The stone dust, a conventional filler in India, was also used for comparing the results. Rheological properties of filler-bitumen (F/B) mastic prepared at different F/B ratios were determined from softening point test, viscosity test, and dynamic shear rheometer test. Strength and durability tests like Marshall stability, retained stability, tensile strength ratio, and static creep tests were conducted on BC mixes with five types of fillers and the results are analyzed and compared. The study indicated that all the four groups of fly ashes are suitable for use in BC mixes with fly ashes in group 4 having the best performance. The optimum filler content is 7% and properties of fly ash BC mixes are better than those of conventional mix.

Performance Characteristics of Bituminous Concrete with Industrial Wastes as Filler

Granite and marble dust from the stone industry and fly ash from thermal power plants are waste products that are produced in large quantities in India. The physical properties of these materials meet the requirements laid for fillers in Indian specifications. This study explores the possible use of these three industrial wastes, along with hydrated lime and conventional stone dust from quartzite, as filler in bituminous construction. Different test procedures are used to examine the void and clay content in the five fillers. Bituminous concrete (BC) mixes were designed according to the Marshall method at four different percentages of the five types of fillers. The performance of bituminous concrete mixes is studied through moisture susceptibility, static creep, flexural fatigue, and wheel-tracking tests. The results suggest that marble dust, granite dust, and fly ash have good potential for their use as filler in bituminous mixes. Among the three industrial wastes, marble dust is the most promising filler and will prove to be very economical also, as mixes with marble dust have the lowest optimum binder content (OBC).

Evaluation of Frictional Pavement Resistance as a Function of Aggregate Physical Properties

AbstractFrictional resistance or skid resistance on pavement surfaces can quantify the safety aspects of road users and impact the efficiency of their travel. Skid resistance primarily depends on t...

Calibration of HDM-4 models for Indian conditions of flexible pavement having modified bitumen in wearing course

Abstract India is developing her national highway network through widening and rehabilitation of existing highways along with the construction of expressways in different phases, since 1999. Unprecedented growth of road traffic, high variations in pavement temperature and need of long lasting pavements have increased the use of modified bitumen specifically in wearing courses of many flexible pavement road sections of national highway network in entire country. Crumb rubber-modified bitumen (CRMB) and polymer-modified bitumen (PMB) of different grades are mostly used modified binders under different climatic and environmental conditions. During the design life, bituminous road sections show different rates of initiation and propagation of distresses under varying traffic and climatic conditions. In this study, an effort has been made to calibrate the internationally recognised Highway Development & Management (HDM-4) road deterioration models for the selected flexible pavement sections over time with traffic. The different road distresses are modelled using HDM-4 tool for the newly constructed flexible pavement sections of Indian national highway network having modified binder in bituminous concrete (BC) mixes which are located in different regions of the country. Pavement condition data of 23 in-service flexible pavement sections were collected for three consecutive years starting from 2011 to end of the year 2013. Data collected from the study were analysed for calibration and validation of HDM-4 distress models for similar climatic conditions, pavement compositions and traffic loading characteristics. The results of this study are useful for developing pavement maintenance management strategies for Indian national highway network with similar climatic conditions, pavement compositions and traffic characteristics.

Rheology of modified binders under varying doses of WMA additive–Sasobit

ABSTRACT Use of warm mix asphalt (WMA) technology to reduce construction temperatures of asphalt mix has gained strong interest worldwide. However, the technology is still in its inception stage in India. Present study evaluated the rheological properties of polymer- and crumb rubber-modified bitumen with various doses of WMA additive Sasobit (1%, 2%, and 3% by binder weight). Frequency sweep and temperature sweep results showed that increase in Sasobit content improved elastic properties of binders. Creep, repeated creep recovery, and multiple stress creep recovery results showed better resistance toward permanent deformation for Sasobit-modified binders in comparison to control binders.

Moisture susceptibility of WMA mixes with modified bituminous binders

ABSTRACT Moisture-induced damage has been a major concern associated with warm mix asphalt (WMA). This study focused on the evaluation of moisture susceptibility characteristics of WMA mixes with different WMA additives and modified bituminous binders through the tensile strength ratio (TSR) and retained Marshall stability (RMS) tests. Experimental design included two binders (polymer and crumb rubber modified), four production temperatures, and two additives (Evotherm and Sasobit), each with a different dosage. Results indicated that (i) WMA additive type and its dosage had significant effect on moisture performance of warm mixes, and (ii) Evotherm mixes exhibited higher TSR and RMS values compared to Sasobit. The results were also analyzed statistically.

Fatigue characterisation of modified asphalt binders containing warm mix asphalt additives

Fatigue is one of the major distresses in asphalt pavements and is strongly influenced by the properties of asphalt binder. Use of warm mix asphalt (WMA) additives allows production of asphalt mixes at lower temperatures than conventional hot mix asphalt. Lower production temperatures reduce the oxidative ageing of binders and thus addition of WMA additives may significantly impact fatigue performance of the binders and the mixes. The existing Superpave specifications prescribe the parameter G*sin δ as an indicator for fatigue behaviour of asphalt binder. In view of critical weaknesses associated with G*sin δ, several test procedures have been proposed for evaluating the fatigue performance of asphalt binder. The current study investigated fatigue characteristics of two modified binders (polymer- and crumb rubber-modified, PMB and CRMB) containing different dosages of two WMA additives: an organic additive, and a chemical additive. A total of twelve binders including ten warm asphalt binders and two control binders were studied. Five binder fatigue test procedures were employed in the study: Superpave fatigue parameter G*sin δ, linear amplitude sweep (LAS) test, DSR-based elastic recovery (DSR-ER) test, elastic recovery from MSCR (MSCR-ER) test, and binder yield energy test (BYET). Additionally, mixes were prepared and evaluated for fatigue using indirect tensile fatigue test. Results of the study showed that PMB and CRMB binders containing the chemical additive performed better in fatigue than the control binders and the binders containing the organic additive. The trends of mix fatigue life corroborated the binder fatigue results. Further, the results showed that monotonic test procedures (DSR-ER and BYET) produced the best correlations with mix fatigue results.