Length change data underlying the publication: Creep in carbonatable binders: Investigating non-hydraulic lime mortars

<strong>CONTEXT:</strong>This dataset provides the experimentally measured <strong>length change strains of air lime-containing mortars</strong>. The objective was to study the role of carbonation and curing conditions in volume stability and to generate reproducible long-term length change data that can be used to support the calculation of total creep in non-hydraulic binders, such as air lime.<br><strong>GROUPS &amp; MATERIALS:</strong>Mortars were prepared with four binder compositions—<strong>C100L0, C50L50, C33L67, and C0L100</strong>—representing varying proportions of Portland cement (CEM II/A-L 32.5R) and air lime (CL90-S). The number after <strong>'C'</strong> indicates the cement content (binder volume %), while the number after <strong>'L'</strong> indicates the air lime content. For example, C33L67 means that 33 % of the binder is Portland cement and 67 % is air lime. Standard siliceous sand (0–2 mm, EN 196-1:2016) and tap water were used. Specimens were cured under three different regimes <strong>(Curing regimes A, B, and C)</strong> and monitored for length change for up to 240 days.<br><strong>PRODUCTION OF SPECIMENS:</strong>To ensure comparability across all mixtures, the flow diameter was fixed at (164 ± 7) mm, as specified in <strong>EN 459-2:2021</strong>. A consistent mixing procedure was adopted: in total, four minutes of mixing, followed by casting in two layers. Each layer was compacted by mechanical vibration for 30 seconds, in accordance with <strong>EN 459-2:2021</strong> and <strong>EN 196-1:2016</strong>.<br><strong>CURING CONDITIONS:</strong>After initial curing for 7 days in a humid chamber at (95 ± 5) % RH and (21 ± 2) °C (<strong>EN 1015-11:2019</strong>), specimens were subjected to three curing regimes:<strong>Curing regime A</strong>: at natural atmospheric conditions (~0.04 % CO₂), until reaching 28 days.<strong>Curing regime B</strong>: at natural atmospheric conditions (~0.04 % CO₂), until reaching 91 days.<strong>Curing regime C</strong>: in an accelerated carbonation chamber (1 % CO₂), until reaching 28 days.Throughout curing and testing, all groups were maintained at (21 ± 2) °C and (55 ± 5) %. Except for C100L0 (Curing regime A), which was kept at (95 ± 5) % RH, (21 ± 2) °C, and (~0.04 % CO₂) until reaching 28 days, in accordance with <strong>EN 1015-11:2019</strong>.<br><strong>TESTING PROTOCOL:</strong>Length change was measured in accordance with EN 12390-16:2019:<strong>Monitoring duration</strong>: 56 days (Curing regime A) and 240 days (Treatments B and C).<strong>Specimens</strong>: two prisms (10 × 10 × 40 cm) per group per curing regime, providing four measurement points per group in each curing regime.<strong>Measurement</strong>: manual readings with dial gauges (± 0.001 mm) at the intervals recommended by <strong>EN 12390-16:2019</strong>.<strong>Adjustment</strong>: Apart from the identification of outliers, no post-processing, normalization, or fitting has been applied.<strong>Strain calculation</strong>: based on a 20 cm gauge length.<br><strong>VALUE OF THE DATA:</strong>This dataset provides long-term length change strain measurements (up to 240 days) for air lime-containing mortars under three well-defined curing regimes (A, B, and C). It enables analysis of how binder composition and curing environment influence expansion, shrinkage, and overall volume stability. The dataset is valuable for:Assessing the suitability of <strong>EN 12390-16</strong> for non-hydraulic binders.Comparing accelerated and natural carbonation in relation to length change.Supporting model development and calibration for shrinkage/expansion prediction in lime-rich mortars.Complementing the total strain dataset by providing the free length change component under identical curing conditions.Contributing reproducible evidence to both conservation practice and sustainable construction research.