PSI - Issue 70

Saurav Kar et al. / Procedia Structural Integrity 70 (2025) 674–681

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1. Introduction Social and political agendas have created a major shift in focus on construction materials, especially on sustainability, resource management, and performance optimization. Concrete still remains the predominant material as construction all around the globe and has been at the epicenter of this shift. One of the most important tactics in mitigating its negative impact on nature is the semi-substitute of traditional cement binder with Supplementary Cementitious Materials (SCMs). Amongst these, fly ash- a by-product of burning coal in thermal power plants- stands out as a dependable and sustainable alternative due to its pozzolanic reactivity, availability, and beneficial effects on long-term concrete performance. The positive impact of fly ash on concrete includes improved workability, reduced hydration heat, increased durability and protection against aggressive environments and obviously it’s zero cost . Nevertheless, most interdependent variables affect structural response of pulverised fuel ash concrete, including the ratio of water-to-reactive and non-reactive binder (w/b) and percentage of fly ash, which tends to be the most important along others. It becomes even more complicated when their interaction is brought into consideration across different concrete grades, which are characterized by varying binder contents and strength requirements. In order to systematically analyze and predict influence of these parameters on the crushing strength of concrete, regression analysis is employed as a robust statistical method. Regression modelling enables the establishment of empirical relationships between independent variables (such as fly ash replacement levels and w/b ratios) and the dependent variable (compressive strength), thus reducing reliance on extensive trial-and-error experimentation. In the context of this study, regression models are developed for various concrete grades incorporating fly ash at different replacement levels and subjected to varying w/b ratios. These models serve as predictive instruments for compressive strength, enabling engineers to make informed choices in the design of sustainable, high-performance concretes. This current experimental study and analytical study is conducted to verify the regression model, which can be best fit for concrete mix proportioning with high fly ash content via a new mix design technique.

Nomenclature HVFA High Volume fly ash F ash Fly ash SF Silica Fume sp Superplasticizer F ash fly ash content σ comp

compressive strength obtained

S xy R 2

standard error

Correlation coefficient

k P

cementing efficiency of fly ash

% of fly ash in binder

W Fash weight of fly ash

Literature Review 2.1. Compressive Strength Prediction Using Linear Regression Method

Tiza et al. (2023) performed an experimental and analytical study focusing on strength prediction of concrete constructed with cement kiln replacements using a linear regression method. The study intended to develop a mechanistic model using experimental data collected by factoring different values of cement replacement, which ranged from 10% to 35%. Concrete specimens were created with consistent ratios of water and cement and underwent a series of compressive, tensile, and flexural strength tests after standard curing by Shoaib et al. (2000). Among the tested mixes, the 20% replacement level yielded the highest average compressive strength (25.6 MPa), surpassing that of the conventional OPC mix (23.9 MPa), suggesting that moderate replacement levels optimize strength characteristics by Maslehuddin et al. (2009).