need be used to hold the assembly of the base matrix frames 1 in the desired configuration on the ground with the assembly of base matrix frames 1 in place the next major component f the system a grout channel forming or grout holding frame 20 is lowered into place on top of each base matrix frame 1 as can be seen in fig1 the grout holding frame 20 is a grid matrix frame of longitudinal and transverse members 21 22 configured directly to correspond to the longitudinal and transverse border walls 4 and partitioning walls 2 3 of the base matrix frame 1 so as to overlie cap their upper edges the grout holding frame 20 is suitably substantially rigid at least in so far as the mutual spacing of the longitudinal and transverse members is defined but may have the nature of a sheet that can be stored in a rolled up state and then rolled out over the base matrix frame 1 the skeleton of the grout holding frame 20 may like the base matrix frame 1 also be formed of pva coated card compressed paper it carries beneath it strips of grout 23 extending the length of the longitudinal and transverse members 21 22 and glued to the underside of the grout holding frame 20 by a peelable adhesive that will enable the frame 20 to subsequently be peeled away from the grout strips 23 leaving them in place along the top edges of the.