Please choose all incorrect statements about the curling in

Please choose all incorrect statements about the curling in rigid pavements.
(a) Curling stresses are mainly induced by the temperature differentials at the top and bottom of concrete slab
(b) The curl up behavior usually takes place when temperature at the surface of slab is greater than the bottom temperature.
(c) When curl ups occur, the surface of concrete usually experiences tension at the surface.
(d) Irrespective of its magnitude and condition (tension versus compression), curling stresses must be included into the structural design of pavement.
(e) Influence charts are one of tools to estimate the curling stress.

Solution

The incorrect statements are:

(b)    Reason: at night temperature is greater at bottom than top and may cause curling

(c) Reason: When temperature on top is higher than bottom surface, then top tends to expand and bottom tends to contract resulting in compressive stress at top and tensile stress at bottom and vice versa.

(e) Influence charts are not related to estimation of curling stresses