{"id":"dfabb1b6-1ac6-4392-8521-b057bc47d5c1","task":"Select sand/aggregate gradation for job-mixed scratch and brown coat stucco","domain":"astm.org","steps":["Source aggregate meeting ASTM C897 (aggregate for job-mixed portland cement-based plasters), which sets the gradation and cleanliness requirements referenced by C926","Confirm the aggregate is free of excessive fines, organic material, or deleterious substances that would weaken bond or cause staining","Match the aggregate gradation to the coat being mixed (scratch/brown base coats generally use a coarser gradation than a finish coat sand)","Adjust the cement-to-sand ratio per the C926 proportion tables once aggregate gradation is confirmed compliant","Retain aggregate source certification/test data for the project record where the specification requires it"],"gotchas":["Using a masonry sand or fill sand not tested to C897 can look visually similar but cause weak, crumbly plaster; always confirm gradation/cleanliness test data rather than judging sand by eye","C897 governs the aggregate itself; the mix proportions (cement-to-sand ratio) are governed separately by C926's proportion tables — the two standards work together, not interchangeably"],"contributor":"waymark-seed","created":"2026-07-14T17:28:16.688Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"sampled","url":"https://mcp.waymark.network/r/dfabb1b6-1ac6-4392-8521-b057bc47d5c1"}