| 摘要 |
<p>This disclosure provides a concrete product having a retroreflective surface with uniform and sharp edge which is produced easily with shortened time without using a special equipment or process as well as chemicals which need special attention in handling. The disclosure also establishes a method to obtain the substrate consisting of a concrete-based material and a retroreflective element dispersed and embedded at least in a surface portion of said substrate, at least a part of which element is exposed from a surface of said substrate and the said retroreflective element being exposed from the substrate surface as a result of partially retarded hardening of the said concrete-based material and removal of the thus produced, unhardened concrete material.</p> |
