Faculty Publications
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Item Experimental Studies on Self-Compacting Alkali Activated Slag Concrete Mixes Incorporating Reclaimed Asphalt Pavement as Fine Aggregate(Trans Tech Publications Ltd, 2023) Joy, A.; Manjunath, R.; Neha, S.N.; Prashanth, M.H.Here performance evaluation of Self Compacting Alkali Activated Slag Concrete incorporating Reclaimed Asphalt Pavement as fine aggregate was carried out. Investigation on mechanical properties by replacing the fine aggregate by Reclaimed Asphalt Pavement in different proportions were also evaluated. Development of Self Compacting Alkali Activated Concrete mixes (SCAAC) was made with GGBFS and Lime are used binders, with binder content varying between 550 to 650 kg/m3 of fresh concrete and lime content varying from 10% to 20% of binder content. The net W/B ratio of the mixes was kept around 0.57. The fine aggregate was replaced by Reclaimed Asphalt Pavement with percentage replacement from 50 to 100% of Crushed Stone Sand. The alkaline solutions had Na2O dosage percentages in the range 5-6% with a constant activator modulus maintained at 1. By using Minitab Statistical Software nine mixes were produced with 4 factors and 3 levels. In this study the TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) optimization technique was carried out to know the effectiveness. Results showed the slump flow greater than 650 mm, with their L–Box, U-box and V-Funnel values ranging between 0.85,20mm and10s respectively, results showed enhanced mechanical properties as compared to control OPCC mix. © 2023 Trans Tech Publications Ltd, All Rights Reserved.Item Flexural behavior of reinforced high performance self-compacting alkali activated slag concrete beams(Associated Cement Companies Ltd., 2020) Manjunath, R.; Prashanth, M.H.; Narasimhan, M.C.; Bala Bharathi, U.K.The present manuscript discusses the results of a series of tests conducted to study, in detail, the performance of reinforced, alkali activated slag concrete beams in terms of their flexural behavior. The present authors have developed and evaluated the performance of a new class of high-performance, self-compacting, alkali-activated slag concrete (HPAASC) mixes, using three industrial by-products, all from the iron and steel industry. While these HPAASC mixes have higher compressive strengths (around 70-90 MPa), reasonable splitting and flexural strengths along with moduli of elasticity, here, in this investigation, reinforced concrete beams made of these mixes are evaluated for their flexural performances in order to promote their applicability in large-scale infrastructural applications. Twelve under-reinforced concrete beams, were cast and were tested. Their flexural behaviors were experimentally evaluated in terms of loads at first crack, ultimate loads, strain-distributions, their load-deflection characteristics along with ductility values. Results of the present study indicate that, all the reinforced beams made of HPAASC mixes exhibit comparable flexural performances, as compared to that of beams cast with a reference OPC-based concrete mix, making a strong case for the possible application of these HPAASC mixes as structural elements in large-scale infrastructure projects. © 2020, Associated Cement Companies Ltd.. All rights reserved.Item Flexural and fracture performance of fiber reinforced self compacting alkali activated concrete– A DOE approach(Elsevier B.V., 2024) Prakash, G.B.; Prashanth, M.H.; Narasimhan, M.C.; Mahendra, K.; Das, A.K.Owing to their much-reduced carbon footprint and lower embodied energy, compared to conventional Portland Cement (OPC-based) Concrete mixes, Alkali Activated Concrete (AAC) mixes represent a pivotal advancement towards achieving sustainability goals. The fracture properties were investigated using Three-Point Bending Tests (3-PBT) under the mode I failure mechanism. This study utilises Taguchi analysis to analyse and optimise Self-Compacting Alkali-Activated Concrete (SAAC), focusing mainly on its flexural strength and fracture characteristics. An L-16 orthogonal array of experiments with three input parameters − replacement of Blast Furnace Slag (BFS) with Fly ash (FA) (0 %, 30 %, 40 %, and 50 %), Steel Fibers (SF) volume content (0 %, 0.25 %, 0.5 % and 0.75 %) and Notch to Depth (a0/d) ratio (0.2,0.3,0.4 and 0.5), at four levels each, was adopted. The Work of Fracture Method (WFM) and Double K Fracture Criterion (DKFC) were utilised to determine the Fracture Energy (GF) and fracture toughness, respectively. The results obtained from all the sixteen mixes showed that the F0-S0.75-N0.5 mix demonstrated better values in several parameters, such as flexural strength of 7.82 MPa,KICini of 0.928 MPa√m, KICuns of 6.99 MPa√m and KICini/ KICuns of 0.133. A maximum GF of 2350 N/m was obtained with F50-S0.75-N0.2 mix. However, all the inferior values of these parameters were observed with F50-S0-N0.5 mix, which recorded a flexural strength of 4.90 MPa, KICini of 0.612 MPa√m,KICuns of 1.16 MPa√m, KICini/ KICuns of 0.528 and GF of 125 N/m. Through Taguchi analysis, the optimal combination for flexural strength was identified as FA 0 %, SF 0.75 %, and a0/d 0.5 and for both Initial Fracture Toughness (KICini) and Unstable Fracture Toughness (KICuns) at FA 0 %, SF 0.75 % and a0/d 0.4. For both the ratio of initial to unstable fracture toughness (KICini/ KICuns) and fracture energy (GF), the optimum combination was FA 0 %, SF 0.75 % and a0/d 0.2. Furthermore, the results indicate that FA significantly influences KICini, while SF predominantly affects all other parameters. The predictive performance of the regression equations demonstrates good agreement with experimental outcomes. © 2024 Elsevier LtdItem Development and performance evaluation of self-compacting lightweight alkali-activated concrete incorporating hydroton clay balls(Elsevier Ltd, 2025) Kuttagola, I.; Prashanth, M.H.Alkali-activated concrete has emerged as a promising alternative in construction due to its enhanced performance characteristics and reduced carbon footprint. This study introduces a novel category of self-compacting lightweight alkali-activated concrete using hydroton clay balls (lightweight expanded clay aggregate, LECA) as coarse aggregate and manufactured sand as fine aggregate. The research investigates the influence of fly ash content in the binder and maximum aggregate size (MAS) on the mechanical properties of the concrete mixes. Three series of mixes were developed with MAS varying at 10 mm, 12.5 mm, and 16 mm, and fly ash proportions at 0 %, 30 %, and 50 %. A novel pre-treatment method involving geopolymer slurry was employed to enhance the stability of LECA by mitigating water absorption, crucial for achieving self-compacting properties. The lightweight concrete mixes demonstrated excellent filling and passing abilities, adhering to EFNARC guidelines, with the mix L10FA50 (smallest MAS and highest fly ash) achieving the highest workability. Compared to the normal-weight mix N16G100, the mix L10FA50 recorded 17 % higher slump flow, 45 % better sieve segregation resistance, and 34 % faster V-Funnel flow times. Dry densities of lightweight mixes ranged from 1851 to 1943 kg/m³, about 19–20 % lower than normal-weight concretes. The pre-treated LECA enhanced the mechanical performance of lightweight mixes, achieving maximum compressive strengths of up to 49.17 MPa, splitting tensile strengths of 3.40 MPa, flexural strengths of 8.60 MPa, and fracture energy of 161.51 N/m, approximately 65 % of the normal-weight mixes. Higher strength gains were particularly notable with higher GGBFS content and larger MAS. The microstructural analysis confirmed dense morphologies with C-S-H and C-A-S-H gel formations, contributing to improved strength. This research establishes the feasibility and performance benefits of utilizing LECA in alkali-activated concrete formulations for sustainable construction practices with enhanced mechanical and microstructural properties. © 2025 Institution of Structural EngineersItem Application of Taguchi's optimization techniques for enhancing the fracture characteristics and brittleness of self-compacting alkali-activated concrete(Elsevier B.V., 2025) Kuttagola, I.; Prashanth, M.H.Alkali-activated concrete has emerged as a promising material for energy-efficient construction, offering a technically viable and eco-efficient alternative that aligns with global sustainability goals. This study explores optimizing fracture properties in self-compacting alkali-activated concrete (SAAC) through controlled variations in maximum aggregate size (dmax) and fly ash. A systematic approach incorporating Taguchi's design of experiments (DOE) and ANOVA analysis was employed to identify optimal mix proportions that enhance fracture performance and ductility. The study employed the Weight-Compensated Work of Fracture Method (WWFM) based on curtailment of the tail of the P–? curve to determine the size-independent fracture energy (GF), enhancing the reliability of SAAC in structural applications. Additionally, the Two-Parameter Fracture Model (TPFM) evaluated the critical stress intensity factor (KsIc) and critical crack tip opening displacement (CTODc), while the MATLAB-based Box-Counting Dimension Method (BCDM) assessed the fractal dimension (D). The findings revealed a higher fracture performance with 0 % fly ash and 16 mm dmax (GF of 206.3 N/m and KsIc of 1.91 MPa?m), suitable for structural applications requiring maximum fracture energy and toughness. The study further tailored a higher ductility mix with 50 % fly ash and 16 mm dmax (CTODc of 0.032 mm and D of 1.144) offering a balanced solution for non-structural applications, providing sufficient strength with enhanced ductility. The closed-form predictive design (CPD) model enables the prediction of ft and KIc under a specified maximum fracture load, offering engineers a practical tool to optimize SAAC formulations by adjusting aggregate sizes and binder proportions for specific project needs. Regression models aligned strongly with experimental and existing literature results, affirming the reliability of predictive performance for future SAAC mix designs. © 2025 Elsevier Ltd