PURPOSE: To enable a harmful vibration to be suppressed further obtain sufficient rigidity as a material, by using a cement hardening structure constituted by containing cement, superfine dust, high performance water reducing agent, water and an optional amount of aggregate.

CONSTITUTION: Various kinds of Portland cement, such as normal, early- strength, super high-early-strength, and white cement, are generally used. Superfine dust, with which an air hole between grains is filled by the existence between the cement grains, is desired that an averaged grain size of the dust is smaller than the averaged grain size of the cement, preferably, in a value of 1μ or less. The high performance water shrinkage agent is a surface-active agent having large dispersion force with no excessive delay of condensation and no excessive range of air being caused even if a large amount of the agent is added to the cement. An aggregate of harder material is desired. A constructional element for a work machine is manufactured by kneading the above materials to be molded.