Precast Concrete Products

Introduction

Vanstone Paving Slabs are precast concrete paving blocks in different sizes from 300 x 300mm to 600 x 600mm and also round Stepping Stones. The slabs are mostly 50mm thick and are available is smooth natural grey, coloured concrete and exposed aggregate finished.

Vanstone Paving Slabs are made for pedestrian use but, depending on the preparation of the paving foundation, may be allowed to take occasional light vehicle traffic. Heavy vehicles may damage the slabs.

Vanstone is not liable for the integrity of paving that has not been installed strictly according to the requirements and used within the limits set by this specification. If any doubt exists, the services of a qualified professional engineer with local knowledge should be employed.

Instructions for installation

Always survey and plan the installation well, taking into consideration required drainage and position of lines and patterns.

For pedestrian Traffic

The substrata must be of a sufficiently sturdy and stable type like gravel, clay free soil or pure hard core filling. Expanding clay, silt, collapsing sand or other soils with poor bearing capacity or with unstable characteristics must be removed to a sufficient depth and replaced with suitable soil. Consult with an engineer if in doubt.

Loosen the subsoil to a depth of 150mm and re-compact at optimum moisture content to at least 90% of the modified AASHTO density to the required level. On top of the compacted layer, use a 20mm bedding layer of clean river sand or crusher sand, which is spread evenly over the surface and leveled. Ten percent of cement may be added to the sand to provide additional strength.

Lay Paving Slabs on the prepared sand and bed-down thoroughly by wriggling each slab a few times left and right. Test evenness of bedding by pressing down alternatively on opposite corners of each slab to determine if any see-saw action occurs. Each slab must be bedded evenly over its whole base and no gaps may be left.

If straight lines, which are neater, are required, the slabs should be laid using a fish line or straight edge.

Leave joints of 15 to 20mm wide between slabs and grout with a semi-dry mixture of cement and river/crusher sand. Use a mix ratio of 1 cement to 3 sand. Work into each joint and compact to ensure that no voids are left. Smooth down the tops of joints by stoking firmly with a brick joining tool. Remove any excess joining material.

For occasional Vehicle Traffic

This method is not for road type traffic but more suitable for domestic driveways provided no heavy vehicles are allowed.

Effect substrata preparation as above but with a final layer density of at least 93% AASHTO. Lay and bed Vanstone Paving Slabs in a 20 to 25mm thick slightly moist bedding mixture of river/crusher sand as above to which was added 20% cement. Keep slabs clean while working. Bed-down as above and allow to cure for 24 hours before grouting and final cleaning.

Important: Cleaning and Sealing

Immediately after a section of Vanstone Paving Slabs has been laid and cement was used in the process, the paving must be cleaned off of all cement residues to prevent staining. This must happen within an hour or two as cement-setting will render cleaning very difficult. Use clean water and a sponge.