Concrete, whether ready-mixed or mixed on site, must reach a characteristic compressive strength of 20 MPa. Cement mortar is one part cement to two of fine aggregate (one to four is allowed for bedding pipes) and must be discarded after standing mixed for over an hour. Mixing water must be free of harmful impurities. In Australia timber exposed to weather is Durability Class 2 or preservative treated and timber in ground contact is Class 1; in New Zealand the treatment levels are H3 and H4 CCA. External coatings on buried pipes in corrosive ground must be moisture-tight, resist the environment and abrasion and not corrode the pipe. Where marking tape is needed it follows AS/NZS 2648.1 and names the service.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.