PSI - Issue 73

Sushant Chaudhary et al. / Procedia Structural Integrity 73 (2025) 19–26 Pratanu Ghosh / Structural Integrity Procedia 00 (2025) 000–000

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1. Introduction The use and demand for concrete have been ever-increasing worldwide, with global production exceeding 4 billion tons annually [Liu Z. et al. (2023)]. With the increase in demand for concrete, the concrete industry is facing increasing pressure to reduce its environmental footprint while maintaining or improving structural performance. The development of high-performance concrete (HPC) with supplementary cementitious materials (SCMs) has gained significant attention. Among these SCMs, zeolite has emerged as a promising alternative due to its pozzolanic properties, widespread availability, and potential to enhance concrete durability while reducing cement consumption. Compressive strength estimation is the critical factor required by engineers and contractors for schedule planning and quality control. Traditionally, this has been accomplished by testing field-cured specimens, which often fail to represent the actual curing conditions of the concrete structure. The maturity method, which uses the unique temperature history of the structure to predict its strength, offers a more reliable approach, allowing for real-time strength estimation without destructive testing, and is standardized in ASTM C1074. The development of maturity can be traced to the early 20 th century when a series of papers dealing with accelerated curing methods was published by McIntosh (1949), Nurse (1949), and Saul (1951). McIntosh (1949) first hypothesized that the rate of hardening of concrete at any moment is directly proportional to the amount by which the curing temperature exceeds the datum temperature. However, he found discrepancies between specimens cured at a higher temperature of 200°F (93°C) versus specimens cured at a control temperature of 60°F (16°C). Later, Nurse (1949) findings on the relationship between 3-day compressive strength and time-temperature product for concrete cured at temperatures ranging from 64°F to 212°F (18°C to 100°C), together with Saul (1951) definition of ‘maturity’ of concrete as the its age multiplied by the average temperature above freezing, led to the birth Nurse-Saul maturity (NSM) function or Temperature-Time Factor (TTF) [ASTM 1074]. To overcome the limitation of linear proportionality assumptions between strength gain and temperature, Freiesleben Hansen and Pedersen (1977) proposed an Arrhenius-based function that describes the effect of temperature on the rate of a chemical reaction. Studies have shown the superiority of the Arrhenius equation over the NSM function, provided an appropriate activation energy value specific to each concrete mixture is determined. Various studies have been conducted on the maturity validation of concrete containing SCMs, with varying conclusions regarding its effectiveness. Carino and Tank (1992) validated the maturity method for the concrete containing fly ash; however, they noted differing strength-maturity relationships from conventional concrete, particularly at later ages. Barnett et al. (2006) found that the concrete containing ground granulated blast-furnace slag (GGBS) required mix-specific calibration for accurate strength prediction due to increased activation energy with the GGBS content. Researchers like Brooks et al. (2007) and Wade et al. (2010) also emphasized the need for mix-specific parameters for SCMs like fly ash, slag, metakaolin, and silica fume to ensure accuracy. There is, however, minimal research on zeolite-based concrete, with existing studies focusing more on mechanical and durability properties [Nagrockiene (2016), Yen Thi Tran (2019)] rather than non-destructive testing like the maturity method. Zeolite, due to its high-water demand, slower hydration rate, and altered temperature profile, can have significantly different effects on the strength-maturity curve and hence requires more investigation in terms of applicability and accuracy of the maturity method. The present research addresses these knowledge gaps by systematically evaluating the effectiveness of the NSM and Arrhenius maturity functions and various strength prediction models. This study provides practical guidance for implementing the maturity method in construction projects utilizing zeolite-based concrete by determining appropriate maturity parameters and analyzing the prediction accuracy for varying zeolite content. 2. Research Significance and Objectives This research analyzes the maturity method's effectiveness and accuracy for estimating zeolite-based high performance concrete's compressive strength. The specific research objectives include: • To validate the applicability of the maturity method for predicting the strength development of zeolite based HPCs with various proportions of natural zeolite as a partial replacement of cement. • To compare the accuracy of different maturity functions—specifically the Nurse-Saul and Arrhenius