Contradictory effects of basalt fiber on chloride transport in concrete: a scopus-centered systematic review and study-level quantitative synthesis

Basalt fiber (BF) can improve, worsen, or reverse chloride transport in concrete. We systematically assessed matched BF-only contrasts across rapid chloride permeability (RCPT), diffusion, migration, chloride-content, and penetration-depth outcomes, treating each experimental program as independent. Scopus was searched on 30 August 2026 with three queries (1,108 records); normalized exact-title deduplication left 874 records for screening. Reporting completeness and extraction provenance were appraised; no validated risk-of-bias tool was used. The final dataset contained 125 effects from 24 program clusters (26 reports); 17 sought reports were not retrieved. RCPT effects averaged B = 0.039 (14 clusters; 95% cluster-bootstrap interval − 0.142 to 0.209), and diffusion effects averaged B = 0.047 (7 clusters; −0.184 to 0.298); positive B = − ln(BF/control) indicates a lower measured chloride indicator. Smaller outcome families were descriptive. An exploratory normalized-dose model (12 studies, 79 rows) yielded a concave interior maximum in 52.3% of cluster-bootstrap samples, but coefficient and turning-point intervals were broad. One author screened and extracted data without independent duplicate review; within-condition variances were unavailable. The review was Scopus-only and not prospectively registered. Results support neither a transferable BF dosage optimum nor causal test-method effects. No external funding was received.