GATE 2019 CE (CE1) – Question 22
An isolated concrete pavement slab of length L rests on a frictionless base. Top and bottom temperatures are $T_t$ and $T_b$, respectively, with $T_t>T_b$. Thermal-expansion coefficient is α and elastic modulus E. With concrete unit weight zero, find maximum thermal stress.
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Correct answer: (D) zero
Explanation
With no base friction,weight or imposed restraint,the slab may freely expand and curl to accommodate the thermal strain gradient. No elastic strain is needed to enforce compatibility,so the induced stress is **zero,D**. Thermal stress requires restraint,not temperature difference alone.