Journal Articles
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Item A comparative study on properties of porous friction course mixes with neat bitumen and modified binders(2009) Suresha, S.N.; George, V.; Ravi Shankar, A.U.R.This paper summarises details of the laboratory investigation on the effect of various binders on the performance and durability of porous friction course (PFC) mixes. Three different modified binders and neat bitumen were investigated for three different aggregate gradations at two predetermined binder contents. The performance was evaluated in terms of stone-on-stone contact condition, air voids, and hydraulic-conductivity of compacted PFC mixes. The structural durability was investigated based on aged abrasion loss and moisture susceptibility. The findings provide a better understanding of the effect of each binder type on the performance and durability of PFC mixes. Crown Copyright © 2008.Item Evaluation of properties of porous friction course mixes for different gyration levels(2009) Suresha, S.N.; George, V.; Shankar, A.U.R.Porous frictions courses (PFCs) are characterized by high percent air voids content, and are widely used as pavement surface drainage layers. This paper presents details on the laboratory investigation performed on evaluation of properties of PFC mixes using the Superpave gyratory compactor. It also, provides a brief review of the latest specifications related to standard practices for mix design and the uses of these mixes adopted by various agencies. Major differences were observed in the design gyrations (Ndesign) and the design aggregate gradations. In this study, six gradations (G) were investigated with binder contents (BCs) ranging between 4.0 and 5.0% by mass of the total mix, for various gyration levels (N). The effect of N, G, and BC on the volumetric properties, unaged abrasion loss, permeability, and the permanent deformation characteristics of PFC mixes were investigated. The experimental results were statistically analyzed to identify the major influencing factors and their significance. © 2009 ASCE.Item Laboratory and theoretical evaluation of clogging behaviour of porous friction course mixes(2010) Suresha, S.N.; George, V.; Ravi Shankar, A.U.The clogging of porous friction courses (PFCs) plays a major role in their resulting performance. Clogging occurs due to deposition of external and internal materials, leading to the loss of permeability and drainage characteristics of PFCs. In this study, investigations were conducted to determine the effect of clogging and de-clogging on the permeability of PFC mixes. Tests were conducted to study the effect of three different clogging materials on PFC mixes prepared using four different aggregate gradations. Permeability tests were conducted using the falling-head concept on cylindrical PFC specimens. The influence of the particle size ratios and the effective air voids on the permeability of fresh, clogged and de-clogged PFC specimens was analysed. Experimental results on the permeability observed were compared with those predicted using theoretical models. Although, the theoretical models tend to overestimate the permeability values, statistical analyses indicate good correlations with the observed results.Item Hydraulic Performance of Pervious Concrete Based on Small Size Aggregates(Hindawi Limited, 2022) Mulu, A.; Jacob, P.; Dwarakish, G.S.The paper aims to study the impact of clogging on pervious concrete mixes and explore a simple method to calculate permeability and clogging using the falling head method in a fabricated unit. The materials used are cementitious materials and aggregates, along with superplasticizers. The cementitious materials used are OPC Grade 53 cement and micro Ground Granulated Blast Furnace Slag (μGGBS). Two separate narrow aggregate gradations are used: 2.36-4.75 mm and 4.75-6.30 mm. The water-binder ratio is taken as 0.25, and the aggregate-binder ratio is taken as 3.33. The compressive strength, permeability, and clogging potential of pervious concrete are calculated. The average permeability for 2.36-4.75 mm and 4.75-6.3 mm is 4.78 mm/s and 8.16 m/s, respectively. The clogging materials used are clay and sand with a concentration of 5 g/l. The introduction of clay slurry reduces the permeability by 69.8% and 74.9%, respectively, and with sand, it decreases by 74.7% and 71.7%, respectively, in its first cycle. The permeability response for such small aggregates is different from the standard coarse aggregates. The paper compares the study's compressive strength, porosity, and permeability with the existing literature. It concludes that the maximum clogging occurs when the clogging material is introduced to the specimen for the first time. The degradation of permeability depends on the clogging particle's particulate size and the concrete matrix's pore size. The smaller aggregates in pervious concrete are not recommended in areas of high siltation. © 2022 Arega Mulu et al.Item Effect of aggregate gradation and bitumen type on mechanical properties of semi-flexible asphalt mixtures(Elsevier Ltd, 2023) Kumar, D.H.; Chinnabhandar, R.K.; Chiranjeevi, K.; Ravi Shankar, A.U.R.Semi-Flexible Asphalt (SFA) mixture is a wearing course in which Open-Graded Asphalt (OGA) mixes having air voids of 20–35% are grouted with cement mortar. The grout consists of cement, sand, superplasticizer, and water. In the present work, an effort was made to assess the effect of the Sand-Cement (S/C) ratio in determining the optimal grout proportions. Taguchi technique combined with Grey Relational Analysis was used to obtain the optimal grout proportion. The optimum grout was found to be the mixture prepared with an S/C ratio of 0.6, a water-to-cement (W/C) ratio of 0.40, and a polycarboxylic ether-based superplasticizer (SP) content of 0.75% by weight of cement. The SP content was the most influencing factor, while the S/C ratio was the second most influencing factor. To investigate the effect of aggregate gradation and bitumen type on the mechanical properties of SFA mixtures, a new aggregate gradation with neat and modified bitumen was used to prepare OGA mixtures and later grouted with optimal grout proportion. The Marshall Stability, compressive strength, Indirect Tensile Strength, Cantabro loss, fatigue resistance, moisture and Oil spillage resistance tests were conducted. The results showed that the SFA mixtures prepared with polymer-modified bitumen and the new aggregate gradation have better mechanical properties, implying the significance of bitumen type and aggregate gradation. © 2023