BITS Faculty Publications
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Item Recycled Aggregate Concrete: Particle Packing Method (PPM) of Mix Design Approach(Springer, 2019) Pradhan, Subhasis; Barai, Sudhir KumarThe reuse of old concrete as a source of aggregate is a reliable alternative to Natural Aggregate (NA) in concrete construction. Because of poor quality of Recycled Aggregate (RA), the performance of Recycled Aggregate Concrete (RAC) is not up to the mark in fresh stage and hardened stage as compared to Natural Aggregate Concrete (NAC). In this work, Recycled Coarse Aggregate (RCA) is replaced 100% to produce RAC. The Particle Packing Method (PPM) is proposed for the mix proportioning of concrete. In PPM, the smaller particles are selected to fill up the voids between large particles and so on. PPM is found out to be cost-effective than IS code method of mix design because of the requirement of lesser quantity of cement. The 7 and 28 days compressive strength of conventional concrete and RAC using PPM design mix are very similar. But, the increment in compressive strength from 28 to 90 days curing is higher for NAC than RACItem Performance of reinforced recycled aggregate concrete beams in flexure: experimental and critical comparative analysis(RILEM, 2018) Barai, Sudhir Kumar; Pradhan, SubhasisThe necessity of sustainable approaches in the construction sector persuades the researchers to utilize the recycled coarse aggregate (RCA) extracted from waste concrete and study the performance of structural members by substituting natural coarse aggregate (NCA) with the RCA. In the present context, the flexural performance of RAC beam was examined on fourteen numbers of beams by completely replacing the NCA with RCA and using four different longitudinal reinforcement ratios (ρ) of 1.61, 1.31, 0.75 and 0.42%. In order to improve the quality of RAC, the particle packing method (PPM) of mix design approach was employed along with the two stage mixing approach (TSMA). The improved mechanical properties owing to the combined effect of PPM design mix and TSMA are also translated in the flexural performance of RAC beams even at 100% use of RCA. A maximum reduction of 35, 4 and 5% in cracking load, yield load and ultimate load, respectively, are observed in RAC beams as compared to the conventional concrete beams. However, the undesirable shear tension mode of failure was witnessed for RAC beams at ρ = 1.61%. A database is prepared by compiling the reported experimental results of RAC beams with shear reinforcement in the available literature. The suitability of the existing expressions to predict the ultimate load is verified for RAC beams and it is observed that, the number of unconservative predictions is significant. In this scenario, an equation is proposed to predict the ultimate load of transversely reinforced RAC beams by operating the flexure database, which shows good correlation with the available experimental results. Further, the increment in shear strength of RAC beams due to the inclusion of stirrups is estimated by using the derived expression.Item Construction and Building Materials Shear performance of recycled aggregate concrete beams: An insight for design aspects(Elsevier, 2018-07) Barai, Sudhir Kumar; Pradhan, SubhasisThe shear failure of reinforced concrete beam is a brittle type of failure and can be dangerous if it is not properly designed. The inherent inferior quality of recycled coarse aggregate (RCA) makes the recycled aggregate concrete (RAC) beams even more vulnerable in shear resistance. This persuades the structural designers to account each of the contributing components in the shear resistance mechanisms seriously, especially that of concrete. In this regard, an experimental investigation was carried out on fourteen beams to examine the shear performance of RAC beams in the absence and presence of transverse reinforcement. Six numbers of beams without transverse reinforcement were tested to examine the contribution of RAC in shear resistance mechanisms and eight beams with shear reinforcement were tested to verify the applicability of the prevailing shear design provisions for RAC beams. The inferior mechanical properties of the RAC are improved satisfactorily by implementing the Particle Packing Method of mix design approach along with the established Two Stage Mixing Approach. However, even with the improved mechanical properties of RAC, the poor performance of RAC beams in shear could not be avoided and a drop of 14% was recorded in the ultimate shear strength of RAC beams without stirrups. A database is prepared by compiling the reported test results of RAC beams with and without transverse reinforcement. An alternative equation is proposed to predict the diagonal tension cracking strength of RAC beams, by using the database of RAC beams without transverse reinforcement and it exhibits a better correlation with the experimental results. Further, in the shear resistance mechanisms of RAC beams the effectiveness of stirrups is studied using the database of RAC beams without and with transverse reinforcement.Item Partially hydrated recycled aggregate concrete: A systematic approach towards sustainable development(Elsevier, 2018-10) Barai, Sudhir Kumar; Pradhan, SubhasisThe experimental investigation on the mechanical properties of partially hydrated recycled aggregate concrete (PHRAC) with the addition of polypropylene fiber (PP fiber) is carried out and compared with the conventional concrete. The 28 days compressive strength is observed to be higher for PHRAC, whereas the tensile strength is lower than natural aggregate concrete (NAC). Based on the mechanical properties, the optimal dosage of PP fiber for both NAC and PHRAC is obtained as 0.6% by weight of cement. The bond strength is also evaluated by conducting the pullout tests using rebar of 12 mm, 16 mm and 20 mm diameter. Higher bond strength is experienced for PHRAC with respect to NAC, whereas the PP fiber addition does not have a significant effect on the bond strength of concrete. Further, -test reveals that, barring flexural tensile strength other mechanical parameters are not influenced either by the type of aggregate or by the incorporation of PP fiber. The cost analysis shows that, the preparation of PHRAC is 4.5% cheaper than NAC.Item Impact of particle packing mix design method on fracture properties of natural and recycled aggregate concrete(Wiley, 2018-11) Barai, Sudhir Kumar; Pradhan, SubhasisThe fracture properties of four types of concrete prepared using natural coarse aggregate and recycled coarse aggregate and conventional and particle packing method (PPM) of mix design approaches are studied. The three-point bending (TPB) test is performed using three different sizes of single edge notched beam. The fracture energy is calculated from the load-CMOD curve obtained in the TPB test, and in this process the load-CMOD curve is curtailed at 2% of the depth of the beam. Based on CTODc and w1 relationship, appropriate softening function is used to estimate the double-K fracture parameters. The fracture energy and fracture toughness parameters of recycled aggregate concrete (RAC) is inferior to the natural aggregate concrete (NAC). The PPM mix design improves the fracture properties of concrete in comparison to the conventional mix design approach. The fracture properties of PPM mix designed RAC are comparable to that of NAC prepared using conventional method.Item Comparative LCA of recycled and natural aggregate concrete using Particle Packing Method and conventional method of design mix(Elsevier, 2019) Barai, Sudhir Kumar; Pradhan, SubhasisIn construction industry, apart from cement, the aggregate type, mix design method and transport distance of raw materials also contribute significantly to the environment related issues. This paper compares environment impacts of recycled coarse aggregate (RCA) and Particle Packing Method (PPM) of mix design approach with the concrete proportioned using natural coarse aggregate (NCA) and IS code method. The system boundary is determined based on cradle-to-gate theory. The primary data regarding the preparation of NCA and RCA are collected from the respective production facilities and Ecoinvent 3.01 is used as background database. Abiotic depletion, abiotic depletion due to fossil fuels, global warming potential, depletion of ozone layer, formation of tropospheric ozone photochemical oxidants, acidification potential, and eutrophication potential are measured using CML baseline method with the help of SimaPro software. Lower environmental impacts are observed for PPM mix designed concrete owing to the requirement of lesser cement quantity. The combination of RCA and PPM mix design approach exhibits minimum environmental impacts. Transport activities are the second largest contributor after cement and hence, sensitivity analysis is carried out to evaluate the influence of different transport scenarios and distances in Indian context. For comparable environmental impact with natural aggregate concrete proportioned using IS code method, the maximum possible supply distance of RCA is determined for different collection distance of C&D waste. The collection distance of C&D waste can be incremented by 9–12 km for each 50 km increment in the supply distance of processed RCA to prepare recycled aggregate concrete.Item Automation in Site Management: A Qualitative Approach(IAARC, 2007) Barai, Sudhir KumarThis paper will address a new approach to construction management: Qualitative Construction Site Assessment System (QCSAS). QCSAS is essentially a site management software package. The objective of this system is three fold. Firstly, it aims to provide a holistic view of construction site to the project manager. It tries to achieve this by tracking essential factors like construction progress, construction quality, safety on site and resource requirement. Secondly, it assesses the condition of all factors on site in qualitative terms by using fuzzy logic. Thirdly, the system intends to achieve smooth information flow between various participants of site, i.e., the site supervisors, procurement officer, quality inspector, safety engineer, planning engineer and project manager with minimal effort and time wastage.Item Abonyi, Janos 43 Alchanatis, Victor 159 Avineri, Erel 221 Ballerini, Lucia 149(Springer, 2009) Barai, Sudhir KumarContains a collection of papers that were presented at the 12th On-line World Conference on Soft Computing in Industrial Applications, held in October 2007Item Neural Networks for Damage Detection in Steel Railway Bridges(IABSE, 1995) Barai, Sudhir KumarThe paper presents Artificial Neural Networks developed for typical steel railway bridges for the purpose of damage detection. Multilayer perceptrons have been used for generating the architecture for the bridges of different configurations. The back propagation algorithm has been adopted for training the network with simulated damage states. The training pairs have been generated using a standard finite element program. The weights of the trained networks have been stored and can be used as a knowledge source independently. It is demonstrated that the trained networks have practical relevance.Item Air Quality Prediction: An Opportunistic Neuro-Ensemble Approach(Sage, 2003) Barai, Sudhir KumarThe present article discusses the development of neural-network-based air quality prediction models which can work with a limited number of data sets and are robust enough to handle data with noise. Five different variations of neural network models (partial recurrent network (PRNM), sequential network construction (SNCM), self-organizing feature maps (SOFM), moving window (MWM), and integrated normalized autoregressive moving average-self-organized feature maps models (NARMA-SOFM)), were implemented in a WINDOWS environment using MATLAB software. Developed models were run to simulate and forecast the daily average data for three parameters: RPM (respirable particulate matter), SO2 (sulphur dioxide), and NO2 (nitrogen dioxide) for the Ashram Chowk location in New Delhi, India. The implemented models were found to predict air quality patterns with modest accuracy. To improve the models’ performance, an innovative approach using an opportunistic ensemble of the first four developed neural network models (OEM) was proposed for predicting the same short-term data. The ensemble approach indeed demonstrated an improvement on earlier models. However, the NARMA-SOFM model performed the best.