CRACKS & JOINTS: 'ARMA-FLEX' TECHNIQUE

• APPLICATIONS

All types of cracks, fissures or joints and crazed areas with a maximum width of 30 mm. Where there is additionally some local deterioration in the vicinity of the crack and where movement is to be expected.

• ADVANTAGES

Level and neat finish; ratio between cross-section of filler and bonding area very favourable, allowing movement without debonding. Groove width maintained at a constant 130 mm (unless excessive local deterioration is evident) as the ‘Armacutter’ milling machine can follow meandering cracks, thus minimising material usage.

• WORK METHOD

At crack, fissure or joint locations Klaruw’s ‘Armacutter’ milling machine is used to cut a groove 130 mm wide and 30 mm deep. Following this, the groove is blasted dry and clean using Klaruw’s purpose designed SuperJet hot air lance during which the horizontal and vertical bonding surfaces are pre-heated. Wide cracks at the bottom of the milled groove are prepared by caulking pre-filling with sealant. Immediately after this, the bottom and vertical walls of the groove are coated with a primer of sealant into which a glass-fibre reinforcing gauze is embedded. Following this the groove is filled with a mixture of single size aggregate and flexible sealant. This mixture is compacted with either a vibrating roller or plate to produce a smooth, neat finish. Finally the repair is completed by applying a thin sealing coat into which calcined bauxite is spread.

• COMMENTS

We have applied the treatment since 1981. Many hundreds of thousands of metres have been repaired using this method with excellent results.