Two-channel field carbonation archive (302 records): phenolphthalein depths, depth-resolved apparent pH, chloride, and cover from existing reinforced concrete in hot-arid/coastal service

This dataset supports the study "Beyond the Phenolphthalein Front: Field-Scale Quantification of Alkalinity Transition Zones in Existing Reinforced Concrete." The research hypothesis is that the phenolphthalein-defined carbonation depth provides only a partial description of the underlying alkalinity field in existing structures, and that jointly interpreting indicator depths with depth-resolved apparent-pH profiles quantifies the finite alkalinity-transition zone that a single indicator reading cannot resolve. Version 2 supersedes Version 1 and is the authoritative public derivative of the underlying field archive. Relative to Version 1, this release: (i) expands the public derivative from the earlier filtered carbonation/cover subset to the reconstructed 302-record archive; (ii) preserves explicit age-evidence classes, including lower-bounded entries such as ">25 years", rather than converting them to point ages; (iii) adds depth-resolved apparent-pH and chloride variables and stable anonymized project/structure identifiers; (iv) removes 12 cover values present in the earlier derivative that could not be traced to the authoritative source records; and (v) includes the complete analysis and simulation code and numerical outputs. The archive was compiled from anonymized commercial condition-assessment records of existing reinforced concrete structures in hot-arid/coastal service. Variables include phenolphthalein carbonation depths with positive, reported-zero, and missing states distinguished; apparent pH measured on powder samples at depths of 30–150 mm; acid-soluble chloride at multiple depths; reported cover bounds with evidence tiers; service-age evidence classes; exposure-domain descriptors; and anonymized project, structure, and location identifiers. Project names, structure names, client names, and site labels were removed to preserve confidentiality. The data support the findings that, at apparent pH 11.5, the alkalinity recovery depth lies on average 27.8 mm beyond the phenolphthalein marker, with a median depth ratio of 2.06 under a structure-aware interval-censored model; that restricting analysis to internally crossing profiles inflates the ratio to 3.04, demonstrating complete-case selection bias; and that 40.9% of records whose indicator front remained below the lower cover bound showed apparent pH below 11.5 at that bound. Apparent pH values are protocol-specific powder-suspension measurements and should not be interpreted as pore-solution pH. Cover information supports screening-level interpretation only. The archive does not support kinetic or service-life calibration, and no such outputs are included.