Vanstone Precast (Pty) Ltd

Introduction

Straight Edge Avalon Flag Stones are precast concrete paving slabs in different sizes from a 225 x 225mm to a 450 x 450mm module and 40mm thick. The slabs have a natural stone texture and colour on top and can be laid in a grid or random pattern using different sizes in the 225mm module.

Straight Edge Avalon Flag Stones 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 delicate surface texture or cause chipping off of corners and edges. Regular vehicular traffic over the flag stones will lead to rapid deterioration of the surface and other damage.

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 Straight Edge Avalon Flag Stones 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 seesaw-action occurs. Each flag stone 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 at least 10mm 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 suitable for regular vehicular traffic purposes like driveways that are used every day but only for occasional use.

Effect substrata preparation as above. On top of this cast a concrete floor slab of 75mm thickness. Use strength 15MPa concrete 15MPa or a 1:3:6 mixture and cast in panels not more than 4m in size nor with lengths of more than twice the width. Lay and bed Straight Edge Avalon Flag Stones in a 20mm thick slightly moist bedding mixture of river/crusher sand to which was added 20% cement as above. 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 Straight Edge Avalon Flag Stones 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.

Straight Edge
Avalon Flag Stones may be sealed with a good quality water-based sealer suitable for cement tiles. The sealing may be done before laying, which will improve protection against staining.