Page 16 - ICJ Jan 2026

TECHNICAL PAPER

Functionally graded pavements: Functionally graded concrete compressive strength loss as compared to freeze-thaw, followed
[36]
has been extensively investigated to improve the flexural by fatigue cycles . Furthermore, early exposure to freeze-thaw,
performance of concrete. In a study on the functionally graded the concrete showed higher residual compressive strength
[36]
cubes, it was observed that the overall strength is higher than but lower flexural fatigue strength . The results indicate that
[35]
the strength of the weaker bottom layer . Further investigation freeze-thaw before fatigue is more detrimental to flexural
confirmed that the increased strength can be attributed to the strength under fatigue, while fatigue before freeze-thaw is more
[36]
[35]
stress distribution at the upper layer . The results suggest that detrimental to compressive strength .
functionally graded pavements can be prepared with a slightly Key contributions: Through the specific scenario of fatigue and
weaker bottom layer for better economy. freeze-thaw, the study demonstrates the coupled effect of the
exposure scenario.
Key contributions: The various studies, at a meta-heuristic level,
provide better techniques for the field application of concrete. Limitations: This work needs to be replicated over various
At a fundamental level, the studies explore different variations scenarios to establish the exact mechanism of the coupled effect
in the mixing and casting procedures and observe their effect and translate it to safety guidelines. Similar studies are also
on the properties of concrete. A better understanding of the needed to understand the interplay between various exposure
effects can help in improving the mixing and casting procedure scenarios.
of concrete.
6.2 Fire safety guidelines for limestone calcined
Limitations: The replicability of the results significantly depends clay cement
on the type of mix and instrument used. Therefore, the results 3
present a direction to the stakeholders towards possible mixing Limestone calcined clay cement (LC ) is a new type of
and casting strategies for various concrete applications. ternary blended cement, and is considered an eco-friendlier
alternative to ordinary Portland cement (OPC) and Portland
pozzolana cement (PPC). One study investigated the thermal
6. UNDERSTANDING FAILURE MECHANISMS degradation patterns of hydrated LC pastes and compared
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[37]
AND DEVELOPMENT OF SAFETY them with hydrated OPC and PPC pastes . Higher thermal
3
GUIDELINES degradation was observed for LC below 110 °C and across
600 °C – 750 °C, due to higher water content and calcium

[37]
The safe and robust industrial application of concrete while carbonates, respectively (Figure 17) . At the same time,
3
balancing economy is one of the major challenges for any lower thermal degradation was observed for LC across
stakeholder. Improving safety often involves taking a factor of 125 °C – 155 °C and 400 °C – 460 °C, due to lower mono-sulfo-

[37]
safety, providing a buffer and/or introducing reserve strength to aluminate (Afm) and portlandite content (Figure 17) . As part
3
concrete. A conservative safety guideline increases costs, while of the study, the loss in residual strength of LC concrete is
[32]
a lenient safety guideline increases risks. Developing suitable compared with OPC and PPC concrete . The results confirmed
3
safety guidelines often involves (i) understanding the failure a greater strength loss in LC concrete when exposed to
3
[32]
elevated temperatures, implying a higher risk . LC presented
mechanism, (ii) developing risk assessment models, and (iii) one case in which the introduction of a safety guideline can
identifying safety guidelines.
ensure a robust industrial application.
6.1 Coupled effect of environmental exposures
In rigid pavements in cold climatic regions, concrete is subjected
to fatigue and freeze-thaw. Exposure to both fatigue and freeze-
thaw results in the creation and growth of micro-cracks till the
[36]
concrete fails . The two exposure phenomena act together in
the field, while testing standards suggest an independent test
for each exposure phenomenon to validate the durability of
LC 3
concrete in the lab . One of the previous studies attempted
[36]
to understand the coupled effect of exposure to fatigue and
freeze-thaw by alternating applications of the two exposure
phenomena .
[36]
The study showed that a coupled exposure scenario creates
a synergistic damage to concrete, based on the exposure
[36]
pattern . Alternating exposure scenario results in higher Figure 17: TGA curve for OPC, PPC, and LC hydrated pastes
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78 THE INDIAN CONCRETE JOURNAL | JANUARY 2026