hi you can do that in the Following Way.
<asp:TemplateField HeaderText="Small Image">
<ItemTemplate>
<asp:Image ID="imgPlacesSmallImage" ImageUrl='<%# String.Concat(@"~\Uploads\PlaceImages\SmallImage\",Eval("placetovisitimages_image")) %>' AlternateText="N.A"
Width="25%" Height="15%" runat="server" />
</ItemTemplate>
<ItemStyle Width="30%" HorizontalAlign="Center" />
</asp:TemplateField>