BITS Faculty Publications

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Durability Performance of Cementitious Mixes with Reclaimed Asphalt Pavement Aggregates
(Springer, 2022-02) Abraham, Sarah Mariam
The effect of fine fraction of Reclaimed Asphalt Pavement (RAP) aggregates on durability characteristics of mortar and concrete were assessed. The natural fine aggregates were replaced by finer fraction of RAP at 25%, 50%, 75% and 100% by volume. Resistance to sulfate and acid attack, drying shrinkage, alkalinity, chloride content and presence of carbonation of the mixes were analyzed. Increase or equivalent strength was observed for both mortar and concrete specimens with 50% or lower RAP replacement level under sulfate attack in sodium sulfate solution in comparison to decrease in strength under sulfate attack in sulfuric acid and acid attack in hydrochloric acid solutions. This is due to difference in formation and filling of pores and microcracks by salt—crystallization products in mortar and concrete. The pore distribution characteristics such as threshold diameter supports this observation as well. The threshold diameter decreases from control mix to 50% RAP mix and then increases. Similar pattern of observation was seen in concrete mixes as well. The drying shrinkage of RAP inclusive cementitious mixes were within the stipulated limits. The RAP inclusive concrete mixes do not pose any threat to the reinforcement due to absence of carbonation, chloride content being lower than the maximum limits and pH content between 12 and 13. From the study, it may be concluded that fine RAP inclusive cementitious mixes have durability life and has the potential to be used as pavement quality concrete.
Effects of Reclaimed Asphalt Pavement aggregates and mineral admixtures on pore structure, mechanical and durability properties of cement mortar
(Elsevier, 2019-08) Abraham, Sarah Mariam
The study evaluate the feasibility of fine fraction of Reclaimed Asphalt Pavement (RAP) aggregates in cementitious mixes. In order to understand the true effect of fine RAP aggregates in cementitious mixes, cement mortar specimens were casted in place of concrete mixes. The natural fine aggregates were partially replaced by RAP aggregates at 25%, 50%, 75% and 100% by volume. In addition to that, cement was partially replaced by mineral admixtures like silica fume and activated sugarcane bagasse ash. The RAP inclusive cement mortars did showcase satisfactory performance in terms of strength and durability. The characteristic compressive strength and commendable flexural strength were achieved by cement mortars with RAP aggregates. Interesting results were observed for resistance against sulfate attack for RAP inclusive cement mortars where gain of strength was obtained for 25% and 50% replacement mixes even after 90 days of sulfate attack. This behavior was replicated by mineral admixture mixes with similar RAP percentage levels. The gain as well as loss in strength due to sulfate attack was substantiated using pore structure characteristics obtained by Mercury Intrusion Porosimetry (MIP). Analysis of data obtained from MIP supports the presence of entrained air in RAP mortars which suggests qualitatively that cement paste is being protected from frost damage and salt decay. This is an initial study and the same shall be replicated for concrete mixes in near future.
Feasibility of reclaimed asphalt pavement in rigid pavement construction
(CRC, 2016) Abraham, Sarah Mariam
Construction and demolition waste along with waste obtained from reconstruction or resurfacing of pavements produces enormous amount of aggregates. Many studies have been carried out to analyse the use of Recycled Concrete Aggregates (RCA) and Reclaimed Asphalt Pavement (RAP) in flexible and rigid pavement respectively, but very few on each other Due to the benefits offered by rigid pavement, developing countries like India is paying more attention in constructing the same. But the lack of funds and natural aggregates seems to be one of the hurdles, which paves the path for use of RAP in rigid pavement construction. The overall objective of this paper is to bring out the studies conducted on use of RAP in rigid pavements. It is concluded that RAP with or without admixtures can be used in rigid pavements after thoroughly investigating its respective properties.
Feasibility of Utilization of ECC Mix in Pavement Construction
(Springer, 2022-06) Abraham, Sarah Mariam
Engineered cementitious composites are a class of high-performance fiber-reinforced cementitious composites with strain hardening and multiple cracking properties. The specialty of engineered cementitious composite is its tensile strain carrying capacity to be 300–500 times that of conventional concrete. Analysis results suggest that engineered cementitious composite can greatly extend the service life of the structure due to its high fatigue and ductility performance. This has led to the wide acceptability of engineered cementitious composite and has the potential to be used as an overlay, interlayer, and even as a surface course in pavement construction. The present paper discusses the advantages and disadvantages of engineered cementitious composite in comparison to conventional concrete in terms of strength and durability characteristics, life cycle costs, and field applications. It has summarized the performance of engineered cementitious composite in different courses of the pavement. In this study, an empirical relation has been derived for a relation between flexural strength and compressive strength of the engineered cementitious composite.
Influence of RAP aggregates on strength, durability and porosity of cement mortar
(Elsevier, 2018-11) Abraham, Sarah Mariam
The influence of fine fraction of Reclaimed Asphalt Pavement (RAP) aggregates on mechanical, durability and porosity characteristics of cement mortar was studied when the same was used as a replacement of Natural fine aggregates (NA) at 25%, 50%, 75% and 100% by volume. The stipulated 28-day characteristic compressive strength was achieved by mortar mixes with 25% and 50% of RAP content. Porosity, determined through Mercury Intrusion Porosimetry (MIP), increases with RAP content and existing strength – porosity models (Hasselman D.P.H, Balshin M.Y, Ryshkewitch E. and Schiller K.K.) holds good. Drying shrinkage of RAP mortar mixes showed erratic behavior, whereas partially replaced mixes (25% and 50%) showed increase in compressive strength under sulfate attack.
Laboratory Research on Reclaimed Asphalt Pavement – Inclusive Cementitious Mixtures
(ACI Material Journal, 2020-03) Abraham, Sarah Mariam
Procurement of natural aggregates (NA) leads to environmental implications, following which government agencies have closed the quarrying activities. Hence, researchers and industrialists are striving to achieve an alternate source of aggregates to NA. Connectivity of a country through road, rail, and air is one of the primary scales of infrastructural development. India ranks second after the United States in WHUPV RI URDG OHQJWK DQG KRXVHV¶ ÀH[LEOH SDYHPHQWV²WKH majority of which has reached their design life. These pavements either need to be reconstructed or resurfaced accordingly
Pore Structure Characteristics of RAP-Inclusive Cement Mortar and Cement Concrete Using Mercury Intrusion Porosimetry Technique
(ASTM, 2019-03) Abraham, Sarah Mariam
The pore structure characteristics of cement mortar and concrete incorporating reclaimed asphalt pavement (RAP) fine aggregates as part replacements of natural fine aggregates (NAs) were studied using mercury intrusion porosimetry (MIP) technique. NAs were replaced by RAP at 25, 50, 75, and 100 % by volume of total fine aggregates. Mineral admixtures, namely silica fume and activated sugarcane bagasse ash, were incorporated as part replacements of cement as well. MIP technique could identify the mesopores and macropores in the cementitious mixture. Porosity increases with an increase in RAP content in cementitious mixture, owing to larger and porous interfacial transition zone. Total intrusion pore volume increases with an increase in RAP content and is greater than the control mix irrespective of RAP content and mineral admixture. Mesopores and macropores follow a similar trend as total intrusion pore volume, suggesting finer and larger pores in RAP-inclusive cementitious mixtures. Threshold diameters were observed to initially decrease until 50 % RAP content and to increase thereafter for RAP-inclusive cement mortar, suggesting easy penetration of chemical species for higher RAP content mixes. From pore classification studies, entrained air, large capillaries, medium capillaries, and small capillaries were also analyzed. Large capillaries follow a similar trend to threshold diameter, in which the former affects the transport processes in cementitious mixture. RAP-inclusive cementitious mixtures have the ability to resist freeze as well as thaw and salt decay; this is concluded indirectly from pore structure studies. The pore-mass fractal dimension has the ability to describe the pore-solid structure, whereas the pore-surface fractal dimension failed to do so for RAP-inclusive cementitious mixtures.
Strength and permeation characteristics of cement mortar with Reclaimed Asphalt Pavement Aggregates
(2018-04) Abraham, Sarah Mariam
In order to assess the effect of fine fraction of Reclaimed Asphalt Pavement (RAP) aggregates as an alternative to natural fine aggregates (NA), cement mortar samples were prepared with 25%, 50%, 75% and 100% replacement of natural aggregates. The influence of grading of fine aggregates was also studied. Even though the compressive strength, flexural strength and splitting tensile strength were decreasing with increase in RAP content, the mortar mixes possessed minimum strength requirement providing the potential of fine RAP aggregate as an alternative. The trend of sorptivity characteristics of RAP cement mortar were in contradiction to the porosity nature of the same which suggests that the conventional methodology to determine the former will not cater for concrete or mortar mixes with RAP aggregates.
Temperature variation and stresses in unreinforced concrete pavement containing RAP
(Elsevier, 2020-12) Abraham, Sarah Mariam
Temperature profile and corresponding stresses in concrete pavement were investigated on prototype scale. Four prototypes were considered, conventional and 25%, 50% and 75% of fine-Reclaimed Asphalt Pavement (RAP) inclusive concrete mixes. The observed temperature profile during 270-days was nonlinear with higher degree of nonlinearity for conventional mixes. The profile could be represented in quadratic form which annuls the assumption of linear temperature variation in numerous design methodologies. The total temperature stresses were lower for RAP inclusive prototypes. Stresses with linear temperature profile assumption over or under-estimated and failed to identify the nature of the stress due to actual temperature profile.