Damping-imparting composition having high impact durability at low temperature

A thermally curable composition that is a pumpable composition at a temperature in a range of 15 to 60° C., comprising:

• as a component (a):
• (a1) a solid rubber in an amount of between 2.5% and 8% by mass,
• (a2) an olefinic double bond-containing polymer which is liquid or pasty at 22° C., has a styrene content in a range of 10% to 60% by mass and has a glass transition temperature of −30° C. to 20° C. in an amount of less than 5% by mass,
• (a3) a hydrocarbon resin in an amount of, in total with said component (a2), 5% by mass or more and 20% by mass or less, and
• (a4) a liquid polydiene different from (a2) in an amount of 15% by mass or more,
• based on the total mass of the composition;
• and
• as a vulcanization system (b):
• at least one substance selected from the group consisting of the following (b1) to (b3):
• (b1) sulfur and one or more accelerator(s),
• (b2) peroxide vulcanization system or disulfide vulcanization system, and
• (b3) quinones, quinone dioximes or dinitrosobenzene;
• wherein after curing, the loss factor tanδ (50 Hz) measured by a DMA method is 0.5 or more at a temperature in the range of −20 to 0° C.