AS 2699.1:2020 pdf free.Built-in components for masonry construction Part 1: Wall ties.
3.1 Material selection
Materials for wall ties shall be in accordance with Table 3.1.
Determination of the coating thickness of galvanized ties shall be in accordance with Appendix A.
NOTE 1 The method set out in Appendix A for galvanized wall ties may be used for site inspection of an individual article or for inspection of a batch lot, such as supplied to a distributor, or for house lots. It may also be used to demonstrate the galvanized coating thickness for alternative solutions.
NOTE 2 The methods set out in Clause E.2. Appendix E and Clause E.3. Appendix E for identifying 304 and 316 stainless steel wall ties may be used for site inspection of an individual article or for inspection of a batch lot, such as supplied to a distributor or for house lots. If there is any doubt, the stainless steel wall ties should be assessed by examination of the supplier test report or a laboratory as described in Clause E.5. Appendix E.
C3.1 Experience from the 1989 Newcastle earthquake showed that corrosion was found to be worst in the mortar joints of the outer leaf of cavity construction. The salt deposition in the wall cavity and roof space would normally be approximately ha If that experienced on the exterior face of the wall.
Appendix D relates the durability classes Ri to R5 to the ISO 9223 corrosivity categories and locations described in AS 4312—2008. If the location of the structure has been defined according to AS 4312— 2008, then the required durability class for components may be determined using Appendix D,. subject to the in-service conditions described in Clause 2.3.4 being met.
The corrosion rate of wall ties not directly exposed to the atmospheric environment (for example, embedded in mortar or within the cavity) may be correlated with the corrosion rates provided by AS 4312—2008 but the differences in time of wetness and chemical environment between the cavity and a rain-washed exterior mean there is not a constant factor. The corrosion mechanism within masonry is different from the atmosphere due to the accumulation of corrodents and extended time of wetness in the wall cavity whereas the external environment is sometimes rain washed and tends to dry more rapidly.
Galvanized (zinc) steel is resistant to mild alkaline conditions, such as exists in the mortar used in masonry construction. Un cured mortar does attack galvanized steel, although this attack slows once the mortar is cured, and experience has shown the durability is not significantly compromised. The coating types in AS 1397 include the “AZ” and “AM” coatings, which contain significant amounts of aluminium. These aluminium-rich products are susceptible to ongoing rapid corrosion in mortar due to their high aluminium content, and are not suitable for use when wall ties are embedded in fresh mortar.
Stain less steel grade 304 will exhibit rust spotting (tea staining) and crevice corrosion over time, specially in environments where the component is exposed to chlorides such as in marine locations and where it remains unwashed. For wall tie applications, the durability will be satisfactory for the design solutions in Table 3.1.AS 2699.1 pdf download.