try like this..
<asp:gridview id="gvTraininfo" runat="server" xmlns:asp="#unknown">
AutoGenerateColumns="False"
GridLines="None"
AllowPaging="true"
CssClass="mGrid"
AlternatingRowStyle-CssClass="alt">
<columns>
<asp:boundfield datafield="TrainCode" headertext="TrainCode" />
<asp:boundfield datafield="Train_Desc" headertext="Train_Desc" />
<asp:boundfield datafield="Sch_Time" headertext="Sch_Time" />
<asp:templatefield headertext="Image" itemstyle-horizontalalign="Center">
<itemtemplate>
<asp:imagebutton id="ImageButton1" runat="server">
ImageUrl='<%# Eval("fldImageUrl")%>' Width="50px"
Height="50px" Style="cursor: pointer"
/>
</asp:imagebutton></itemtemplate>
</asp:templatefield>
</columns>
</asp:gridview>
and use SQL Select Statement like this
Select TrainCode,Train_Desc,Train_Desc,From,To,'c:/images/'+'logo.jpg' as fldImageUrl from table