We had a tricky little job to undertake in an expensive riverside courtyard development, the brief was to reconstruct the garage area without inconvenience to the residents in the block. The tarmac had been installed in the seventies and had oxidized and crumbled into the sub base, in addition there was some tree root damage from trees that had subsequently been removed.
We used a 3 tonne excavator and a 1 tonne dumper to excavate and remove the decayed material and the areas around the old trees. Material was carefully transported to a designated area, neatly boarded, next to the entrance – where it could be safely removed by grab lorry. The sub base was reconsolidated and amended with an Mot type 3 high stone content sub base to correct levels and falls. The central drain gulley was adjusted to increased the crossfall from the garages and a new C250 25 tonne loading cast iron grating installed on concrete. To the existing planter areas, we used a Marshalls KL kerb in charcoal to form planters using a chamfered profile with internal and external radius pieces to form the corners to the planter detail, giving a nice structure to the planter areas.
We chose to use a 12:1 semi dry lean mix concrete instead of the conventional dense bituminous macadam base course. The lean mix concrete is laid and compacted in the same way as the macadam base course but tends to give a more solid base construction where the whole sub base structure has not been reconstructed from the subgrade up. The lean mix base is a useful addition to the armory when considering the best available options to reconstruct legacy areas where the budget constraints may preclude full depth reconstruction.
Once the lean mix had cured we were able to install a 6mm stone mastic asphalt ‘Tuffdrive’ proprietary surface course, with a bitumen emulsion tack coat applied to the lean mix base. The Tuffdrive performs excellently where there is likely to be static turning in confined areas. Aesthetically the Tuffdrive has a close graded appearance identical to conventional dense bituminous macadams, but is two grades higher in bitumen content and the polymodified binders sets the material off very hard as soon as the materials have cooled from laying temperatures.
Using this format Glenco were able to bring Quality to the Surface as we always strive to do!
