Does Libya Need Freeze–Thaw Provisions in Concrete Design? A Ten-Year Analysis of Daily Temperature Records in 25 Libyan Cities

Abstract

A widespread assumption in Libyan engineering practice holds that freeze–thaw action is irrelevant to local concrete design, yet this assumption has never been tested against climatic records. This study examines it through two questions: do genuine freeze–thaw cycles occur in Libyan cities, and how should these cities be classified under the exposure categories of international concrete codes? Daily minimum air temperature series for 25 cities over ten winter seasons (2015/2016–2025/2026) were retrieved from the NASA POWER database and analyzed in four stages: counting raw freezing days (Tmin ≤ 0 °C); screening them with a qualified-cycle criterion (Tmin ≤ −1 °C and Tmax ≥ +1 °C, a ±1 °C buffer); correcting for grid-cell elevation bias using the standard lapse rate of 6.5 °C/km against documented city elevations; and classifying each city according to the code. Nationally, 227 raw freezing days were recorded in the decade, with none along the entire coastal strip. Elevation correction reversed the apparent map: Ghat fell from 58 days to 3, while Nalut rose from 5 to 62 and Gharyan from 25 to 47, shifting the likely exposure belt to the Nafusa escarpment. The deepest event nationwide was −2.9 °C, and the worst corrected case corresponds to roughly 2.3 potential cycles per year. All 25 cities are judged to fall practically within exposure class F0, with low-cost field temperature logging recommended for the mountain cities whose figures rest on corrective estimation.