Faculty Publications
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Item Application of Andreassen and Modified Andreassen Model on Cementitious Mixture Design: A Review(Springer, 2021) Snehal, K.; Das, B.B.Cement is a widely used construction material and its consumption on large-scale causes environmental degradation; thus, more emphasis is being given on industrial by-products as alternative materials to cement for their sustainable usage. It is necessary that varying particle size of supplementary cementitious particles is to be used for filling the voids to form a dense particle-packed concrete. The selection of right combination of material is tedious job by trials involving different replacement materials and the resultant concrete may show unexpected results; thus, a more suitable method is the selection of materials based on optimum packing of particles. To select the optimum size of replacement materials particle packing models are essential, so that a low-cement concrete can be prepared which will be ecological as well as economical with improved density, low porosity and high compressive strength. It is found that there are different models have been developed to achieve optimal packing. However, application of Andreassen and modified Andreassen models for the particle packing of multiple ingredients of cementitious matrix found to be largely being accepted by the researchers. This paper reviews the application of Andreassen and modified Andreassen models for the effective particle packing investigations on cementitious particles. It also reviews the software’s employed for designing various cementitious mixtures based on Andreassen and modified Andreassen models. © 2021, Springer Nature Singapore Pte Ltd.Item Influence of compression toughness on acoustic emissions of cementitious materials(ICE Publishing subscriptions@icepublishing.com, 2019) Vidya Sagar, R.; Shetty, S.; Bhat, A.This paper reports on the variation of acoustic emission (AE) characteristics with the compression toughness of cementitious materials. The purpose of the study was to understand the relation between compression toughness and AE released during the fracture process in cementitious materials. There is limited knowledge about the 'relation between the compression toughness of cementitious materials and the corresponding AE released'. Specimens of different cementitious mixture compositions were tested as per the ASTM C 39 standard in the laboratory under unconfined uniaxial compression, and simultaneously the released AEs were recorded. Specimens consisted of concrete with 20 mm aggregates, concrete with 12 mm aggregates and mortar. AE monitoring system consisting with resonant type differential AE sensors were used to record the AE parameters. A detailed analysis revealed that an inverse relation may exist between the AE energy (S) and compression toughness (T ac) of the cementitious materials. The properties of cementitious materials that influence the relationship between AE energy and compression toughness and the behaviour of AE signals were studied. © 2019 ICE Publishing: All rights reserved.Item Effect of elevated temperatures on ferrochrome ash based mortars(Associated Cement Companies Ltd., 2019) Kumar, B.; Yaragal, S.C.; Das, B.B.Due to boom in construction sector, large amount of Ordinary Portland Cement (OPC) is being consumed. Cement production is energy intensive and releases large amount of CO2 into atmosphere. Efforts are on to bring down cement consumption by the use of secondary cementitious materials. An attempt is made to study the influence of combined effect of various levels of ferrochrome ash (FCA) and lime, as replacement to OPC for different cement mortar mixtures at elevated temperatures. FCA replacement considered is in the range of 0% to 20% and along with 7% lime as replacement to cement. Compressive strength of cementitious materials is being an important parameter in the design of structures. The main objective of this work is to assess the residual compressive strengths at different levels of temperatures (200, 400, 600, and 800ºC) for a retention period of half an hour. Residual strengths of mortar mixtures produced, using FCA, have shown a good performance. Upto 20% FCA and 7% lime, mixture turns out to be a good elevated temperatures enduring material. This would increase the suggested application for environmental friendly materials. Important differences were seen in microstructural observations with scanning electron microscope (SEM) for various levels of FCA and lime incorporated mortars. © 2019, Associated Cement Companies Ltd. All rights reserved.Item Statistical analysis of acoustic emissions generated during unconfined uniaxial compression of cementitious materials(Elsevier Ltd, 2019) Vidya Sagar, R.; Singh, M.; Deepak, S.; Desai, P.R.The article reports a study on the ‘goodness of fit’ of Weibull and Normal (Gaussian) distributions on the compressive strength and the corresponding Acoustic Emissions (AE) of cementitious materials. An attempt has been made to understand the variation of the parameters of the Weibull distribution and the Gaussian distribution carried out on the uniaxial compressive strength data and the corresponding recorded AE parameters. The statistical analysis of ‘Damage Parameter’ based on the peak amplitude of AE signals was also carried out. It was observed that the Weibull distribution was a better fit than Gaussian distribution for compressive strength and damage parameter. But in the case of AE parameters, Gaussian distribution was a better fit. The results obtained from this statistical study may be an addition to the existing knowledge on the statistical approach of AE associated with cementitious materials. A statistical approach may be suitable in predicting the data values without conducting further experiments. The results may be useful to understand the variation of physical properties such as homogeneity and ductility with the variation of compressive strength of cementitious materials and its corresponding AE parameters. © 2019Item 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 Internal damage growth in quasi-brittle fibre-reinforced cementitious materials under cyclic compressive loading(Structural Engineering Research Centre, 2023) Vidya Sagar, R.; Basu, D.J.; Suhas Reddy, K.V.; Prathap, Y.; Bhuvaneswari, G.; Sai Keerthi, P.This article reports a comparison between the internal damage growth in cementitious materials without fibres and with fibres subjected to elevated amplitude cyclic compressive loading. The damage progression was assessed using ultrasonic testing method and Acoustic Emission (AE) testing. The intricate fracture mechanism in the test specimens causes rise to a higher harmonic generation, which was used as an indicator to the internal damage. The decrement in wave peak amplitude with higher harmonic generation may be regarded as a ‘internal damge growth’ in the deformable solid. The complexity in the fracture mechanism in fibrous cementitious matrix influenced the heterogeneity of the specimen, which is reflected by the steep decrement in the slope of the line plotted using normalized higher harmonic ratio and load. It was observed that the ‘magnitude of the total damage’ developed in plain concrete at the last loading phase was relatively lower than brass coated steel fibre reinforced concrete. This was supported by the damage parameter based on generated AE, where final failure of the specimens preceded an AE avalanche. Therefore, the utilization of a combination of nondestructive testing techniques such as AE and nonlinear ultrasonic testing can offer a more comprehensive understanding of the progression of damage in quasi-brittle cementitious materials. © 2023, Structural Engineering Research Centre. All rights reserved.