How to put a template column in Vaadin-Grid?

I have the following table:

                <vaadin-grid id="temp" style=" height:70vh;">
                  <table>
                    <colgroup>
                      <col name="Column1"/> 
                      <col name="ColumnTime"/>                                
                    </colgroup> 
                    <thead>
                      <tr>
                        <th >Column1</th>
                        <th >ColumnTime</th>
                      </tr>
                   </thead>
                  </table>
                </vaadin-grid>

and my datasource:

{
    "Column1": "My Name",
    "ColumnTime": "<iron-icon icon='image:timelapse' style='cursor:pointer'></iron-icon>"

}

The problem is that the Vaadin-Grid does not deploy the Iron-Icon:

I have noticed that it is because it is within a SPAN element; Which is automatically added by Vaadin, any idea how to make the Iron-Icon deploy?