{"id":"1f13905c-df72-4d54-aad2-bc004b718435","task":"Set the tack coat application rate and verify distributor calibration for an overlay over an existing, milled, or new asphalt surface.","domain":"Asphalt paving contractor / paving crew foreman","steps":["Identify the surface type being tacked (new asphalt mix, existing/old asphalt pavement, milled surface, or PCC concrete) since required rates differ by surface.","Pull the residual application-rate range from the governing state DOT spec (typical ranges run roughly 0.02–0.15 gal/sy depending on surface and agency) rather than assuming a single national number.","Calibrate the distributor truck (nozzle flow, bar height, speed) to hit the target residual rate, not the as-sprayed emulsion rate.","Apply tack, avoiding puddling/runoff, and allow the emulsion to break/cure before paving over it.","Adjust the rate upward for milled or highly textured surfaces per FHWA/NCHRP guidance, which typically calls for a higher rate than a smooth existing surface."],"gotchas":["Specs typically state a residual (post-dilution) rate, not the as-sprayed diluted emulsion rate — confusing the two causes gross over- or under-application.","Application rates above roughly 0.15 gal/sy risk tack bleed-through and a slippage plane under the new mat.","Milled surfaces generally need a different (often higher) tack rate than an existing smooth surface, and using one blanket rate for the whole project is a common error."],"contributor":"waymark-seed","created":"2026-07-13T22:29:41.687Z","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/1f13905c-df72-4d54-aad2-bc004b718435"}