White paper 10 · Annex D
Data tables behind the exhibits
This annex gives the values plotted in every chart of the paper, with units, evidence status and sources, so that readers can check them and reuse them. The same values are published as machine-readable files with the web edition (one JSON file per chart, generated by the script that draws the chart). Schematic diagrams that carry no data are listed in the first table with a note.
Index of exhibits and their data
Table D.1 Exhibits, their data files and evidence status
| Exhibit | Content | Data file | Status | Values |
|---|---|---|---|---|
| Figure ES.1 | Yield force of a 12 mm bar under compliant and defective scenarios | hero_capacity.json | derived | Table D.2 |
| Figure 1.1 | How a reinforced concrete beam works (schematic) | beam_ductility.json | illustrative | No data |
| Figure 1.2 | Stress-strain curves by ductility class (schematic) | stress_strain.json | illustrative | Table D.3 |
| Figure 1.3 | Capacity ratio by mass deficit and yield strength | capacity_heatmap.json | derived | Table D.4 |
| Figure 2.1 | QST cross-section and temperature history (schematic) | qst_section.json | illustrative | No data |
| Figure 2.2 | Nine quality control points in a mini-mill | process_qc.json | illustrative | Table D.5 |
| Figure 2.3 | Carbon equivalent map | cev_map.json | derived | Table D.6 |
| Figure 3.1 | What the tensile test measures (schematic) | tensile_definitions.json | illustrative | No data |
| Figure 3.2 | Rib geometry parameters (schematic) | rib_geometry.json | illustrative | Formula in Table 3.3 |
| Figure 4.1 | Quality infrastructure for rebar in Cameroon | qi_map.json | sourced | Sources in caption |
| Figure 4.2 | Milestones in standardisation and control | timeline.json | sourced | Table D.7 |
| Figure 4.3 | Capacity and demand by product | capacity_demand.json | sourced | Table D.8 |
| Figure 5.1 | Yield-strength distributions under three regimes | yield_distributions.json | derived | Table D.9 |
| Figure 5.2 | Control chart of heat-mean yield (simulated) | spc_chart.json | illustrative | Table D.10 |
| Figure 6.1 | Mass of a 12 m bar: nominal, minimum and undersize | mass_check.json | derived | Table D.11 |
| Figure 6.2 | Probability of detecting light bars by sample size | detection_probability.json | derived | Table D.12 |
| Figure 6.3 | Site acceptance routine | site_flow.json | illustrative | Table D.13 |
| Figure 7.1 | Specimen mill certificate (invented values) | mill_certificate.json | illustrative | No data |
| Figure 7.2 | Price per kilogram and effective price of light bars | price_per_kg.json | derived | Table D.14 |
| Figure 8.1 | Corrosion mechanism and two-stage model (schematic) | corrosion_mechanism.json | illustrative | No data |
| Figure 8.2 | Monthly relative humidity in four cities | humidity.json | sourced | Table D.15 |
| Figure 8.3 | Time to corrosion initiation by cover (model) | chloride_initiation.json | illustrative | Table D.16 |
| Figure 9.1 | Imports of long products by HS line | imports_products.json | sourced | Table D.17 |
| Figure 10.1 | Indicative implementation calendar | roadmap.json | illustrative | Table D.18 |
Source: Cameroon Steel. Data files are published with the web edition.
Safety margin and capacity
Table D.2 Yield force of one nominal 12 mm bar (Figure ES.1)
| Scenario | Yield force (kN) | Ratio to design value |
|---|---|---|
| Certified B500B, typical production (mean yield about 560 MPa) | 63.3 | 1.29 |
| Certified B500B at the characteristic yield of 500 MPa | 56.5 | 1.15 |
| Bar 1 mm undersize (11 mm), yield 500 MPa | 47.5 | 0.97 |
| Fe400 steel sold as Fe500 (yield 400 MPa) | 45.2 | 0.92 |
| Both defects together (11 mm, 400 MPa) | 38.0 | 0.77 |
| Design value: 500 MPa / 1.15 × 113.1 mm² | 49.2 | 1.00 |
Source: derived by Cameroon Steel; partial factor [S36]; mean yield of controlled production [S29].
Table D.3 Parameters of the schematic stress-strain curves (Figure 1.2)
| Curve | Yield Re (MPa) | Tensile Rm (MPa) | Rm/Re | Agt (%) | Strain at fracture (%) |
|---|---|---|---|---|---|
| Class C type | 530 | 647 | 1.22 | 12.0 | 17.0 |
| Class B type | 545 | 627 | 1.15 | 8.0 | 13.0 |
| Class A type (cold-worked, proof stress) | 520 | 560 | 1.08 | 3.0 | 4.5 |
| Out-of-specification bar | 410 | 440 | 1.07 | 1.5 | 2.2 |
Source: illustrative parameters chosen by Cameroon Steel to show the class limits of EN 1992-1-1 Annex C [S30][S36]; not test data.
Table D.4 Marked points of the capacity map (Figure 1.3)
| Point | Mass deficit (%) | Yield (MPa) | Ratio to design value |
|---|---|---|---|
| Certified bar (typical) | 0.0 | 560 | 1.29 |
| At mass tolerance | 4.5 | 500 | 1.10 |
| Fe400 sold as Fe500 | 0.0 | 400 | 0.92 |
| 1 mm undersize (12 to 11 mm) | 16.0 | 500 | 0.97 |
| Both defects | 16.0 | 400 | 0.77 |
Source: derived: ratio = (1 minus deficit) × fy / (500/1.15). Axes span 0% to 20% deficit and 350 to 620 MPa.
Metallurgy
Table D.5 Process steps and quality control points (Figure 2.2)
| Step | Control point |
|---|---|
| Scrap and DRI/HBI yard | Sorting, radiation portal, no sealed containers |
| Electric arc furnace | Bath samples, temperature, oxygen activity |
| Ladle furnace | Spectrometer: C, Mn, Si, P, S, N, Cu, Ceq |
| Continuous caster | Heat number stamped on every billet |
| Billet yard, reheating | Surface defects, macro-etch, furnace profile |
| Rolling mill | Diameter, ovality, rib height and spacing |
| QST quench and temper | Water flow and pressure, surface temperature |
| Cooling bed, cut, bundle | Tensile, bend, rebend, mass per metre |
| Tag and dispatch | Bundle tag, 3.1 certificate, lot release |
Source: Cameroon Steel schematic; common factory production control practice [S31][S38].
Table D.6 Assumptions and windows of the carbon-equivalent map (Figure 2.3)
| Item | Value |
|---|---|
| Formula | Ceq = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
| Assumed Cu + Ni (%) | 0.35 |
| Assumed Cr + Mo + V (%) | 0.15 |
| Cast limit Ceq (%) | 0.50 |
| QST B500B window: C (%) / Mn (%) | 0.17 to 0.22 / 0.65 to 1.05 |
| High-carbon window: C (%) / Mn (%) | 0.26 to 0.31 / 1.15 to 1.55 |
Source: derived; formula and limit [S31][S32]; residuals and windows assumed (Annex A).
Cameroon’s quality infrastructure and market
Table D.7 Milestones plotted in Figure 4.2
| Date | Event | Source |
|---|---|---|
| 5 Aug 1996 | Law 96/11 on standardisation sets the legal basis for Cameroonian standards (NC) | S14 |
| 17 Sep 2009 | Decree 2009/296 organises ANOR, the standards and quality agency | S14 |
| 1 Jul 2015 | Decree 2015/1875/PM creates PECAE, conformity assessment of imports before shipment | S15 |
| 31 May 2016 | Prime Minister’s office suspends rebar imports until further notice | S13 |
| 31 Aug 2016 | PECAE becomes operational (SGS, Intertek, TÜV Rheinland) | S15 |
| 31 May 2021 | Decree 2021/3306/PM amends and clarifies the PECAE programme | S15 |
| 2021 | NC 236:2021, the national standard for rebar (acier pour béton armé), is issued | S04, S05 |
| 20 Apr 2022 | Ministerial order makes NC 236 mandatory: Fe400 and Fe500 ribbed, Fe215 and Fe235 smooth | S04, S05, S09 |
| Apr to Jun 2023 | Import ban reaffirmed; engineers and consumers report substandard and counterfeit bars | S09, S10, S12 |
| 21 Oct 2023 | Homologated producer prices per bar reduced by diameter and grade | S11 |
| 16 Oct 2024 | ANOR withdraws a conformity certificate and recalls Fe450 bars absent from NC 236 | S04, S05 |
| 19 Jan 2026 | Government refuses an industry request to revise the rebar standard (NC 236/2024/06) | S06, S07 |
| 6 Oct 2026 | ANOR simplifies the start of PECAE checks (IM number accepted) | S17 |
Source: as listed; Annex C.
Table D.8 Installed capacity and demand by product, kt per year (Figure 4.3)
| Product | Capacity (kt/yr) | Demand (kt/yr) | Capacity / demand |
|---|---|---|---|
| Rebar | 627 | 180 | 3.5 |
| Wire rod and nails | 72 | 36 | 2.0 |
| Sheets | 43 | 21 | 2.0 |
| Tubes | 34 | 14 | 2.4 |
| Annealed wire | 2.8 | 1.8 | 1.6 |
Source: industry figures reported in Cameroon Tribune, 11 May 2026 [S53]; ratios derived.
Testing and statistics
Table D.9 Parameters and shares of the yield-strength distributions (Figure 5.1)
| Regime | Mean (MPa) | Standard deviation (MPa) | Share below 500 MPa | Share below 400 MPa |
|---|---|---|---|---|
| Certified production: mean 560, sd 30 MPa | 560 | 30 | 2.3% | 0.0% |
| Same mean, uncontrolled spread: sd 80 MPa (CoV 14%) | 560 | 80 | 22.7% | 2.3% |
| Site sample pattern: median below 400 MPa (fitted, sd 75) | 395 | 75 | 91.9% | 52.7% |
Source: derived (normal model); σ = 30 MPa [S29]; CoV 14% [S28]; site pattern fitted to [S19] (illustrative).
Table D.10 Simulated heat-mean yield strengths, MPa (Figure 5.2; mean of heats 1 to 30 = 563.8, control limits 544.5 and 583.2, run rule at heat 46)
| Heats | +0 | +1 | +2 | +3 | +4 | +5 | +6 | +7 | +8 | +9 |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 to 10 | 557.2 | 560.2 | 559.7 | 568.1 | 564.0 | 567.0 | 572.7 | 572.9 | 569.8 | 562.4 |
| 11 to 20 | 560.0 | 559.5 | 563.2 | 565.6 | 558.2 | 556.9 | 568.4 | 551.2 | 564.6 | 569.4 |
| 21 to 30 | 558.1 | 557.1 | 559.9 | 571.2 | 565.0 | 551.0 | 562.6 | 574.1 | 573.9 | 571.0 |
| 31 to 40 | 564.1 | 551.2 | 567.4 | 564.6 | 566.6 | 578.3 | 567.5 | 568.2 | 552.0 | 551.8 |
| 41 to 50 | 555.5 | 558.7 | 550.2 | 547.7 | 554.8 | 554.5 | 552.4 | 558.4 | 559.2 | 553.7 |
| 51 to 60 | 554.6 | 558.3 | 554.3 | 550.4 | 555.7 | 552.4 | 557.3 | 554.0 | 555.2 | 558.1 |
Source: Cameroon Steel simulation, random seed 10 (illustrative).
Defects and site acceptance
Table D.11 Mass of a 12 m bar (Figure 6.1)
| Diameter (mm) | Nominal (kg) | Minimum within tolerance (kg) | 1 mm undersize (kg) | Undersize shortfall |
|---|---|---|---|---|
| 8 | 4.74 | 4.46 | 3.63 | 23.4% |
| 10 | 7.40 | 7.07 | 5.99 | 19.0% |
| 12 | 10.66 | 10.18 | 8.95 | 16.0% |
| 14 | 14.50 | 13.84 | 12.50 | 13.8% |
| 16 | 18.94 | 18.08 | 16.65 | 12.1% |
| 20 | 29.59 | 28.26 | 26.71 | 9.8% |
| 25 | 46.24 | 44.16 | 42.62 | 7.8% |
Source: derived: nominal mass per metre as tabulated (to three decimals) at 7,850 kg/m³; undersize bar and shortfall from the diameters; tolerance [S31][S32].
Table D.12 Probability that at least one light bar is found (Figure 6.2)
| Bars weighed | 10% of bars light | 20% light | 33% light | 50% light |
|---|---|---|---|---|
| 1 | 10% | 20% | 33% | 50% |
| 3 | 27% | 49% | 70% | 88% |
| 5 | 41% | 67% | 87% | 97% |
| 10 | 65% | 89% | 98% | 100% |
Source: derived: 1 minus (1 minus p) to the power n.
Table D.13 Site acceptance steps (Figure 6.3)
| Step | Action |
|---|---|
| 1 Paperwork | Delivery note, mill certificate (EN 10204 type 3.1), product certificate number, heat numbers on tags |
| 2 Marks and tags | Rolled-in mill mark and grade on the bar; bundle tag matches certificate and delivery note |
| 3 Weigh | Weigh three full bars per diameter; compare with nominal mass less 4.5% (6% at 8 mm and below) |
| 4 Look and measure | Measure diameter over ribs and rib spacing; no laps, cracks, deep pitting or flaking rust |
| 5 Bend | Bend a sample 180 degrees round a mandrel of about 4d (larger for big bars): no cracks on the outside |
Source: Cameroon Steel recommended practice.
Table D.14 Homologated price per kilogram and effective price of light bars (Figure 7.2)
| Bar | FCFA/kg at nominal mass | 4.5% light | 10% light | 16% light (one size down at 12 mm) |
|---|---|---|---|---|
| 8 mm Fe400 | 612 | 641 | 680 | 728 |
| 8 mm Fe500 | 648 | 678 | 720 | 771 |
| 10 mm Fe400 | 602 | 631 | 669 | 717 |
| 10 mm Fe500 | 635 | 665 | 705 | 756 |
| 12 mm Fe400 | 601 | 629 | 667 | 715 |
| 12 mm Fe500 | 633 | 663 | 704 | 754 |
| 6 mm | 575 | 602 | 639 | 685 |
Source: homologated prices made public on 21 October 2023 [S11]; per-kilogram values derived (Annex A).
Durability
Table D.15 Mean relative humidity at 2 m,%, 1991 to 2020 (Figure 8.2)
| City | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Kribi | 85 | 87 | 88 | 89 | 89 | 90 | 90 | 90 | 91 | 90 | 89 | 87 | 89 |
| Douala | 81 | 84 | 87 | 88 | 89 | 90 | 90 | 91 | 90 | 89 | 88 | 83 | 88 |
| Yaoundé | 77 | 81 | 86 | 88 | 88 | 88 | 88 | 90 | 90 | 89 | 86 | 80 | 86 |
| Garoua | 19 | 16 | 20 | 43 | 64 | 73 | 80 | 84 | 82 | 74 | 47 | 27 | 53 |
Source: NASA POWER climatology API, modelled [S50].
Table D.16 Years to corrosion initiation in the illustrative chloride model (Figure 8.3)
| Concrete | D (m²/s) | 25 mm cover | 40 mm cover | 50 mm cover |
|---|---|---|---|---|
| Poor concrete: w/c about 0.65, site-batched | 5.0 × 10⁻¹² | 1.6 | 4.1 | 6.4 |
| Ordinary structural concrete: w/c about 0.50 | 1.5 × 10⁻¹² | 5.4 | 13.7 | 21.4 |
| Durable marine mix: w/c 0.40 with slag or fly ash | 5.0 × 10⁻¹³ | 16.1 | 41.1 | 64.2 |
Source: illustrative model: Cs = 1.5%, Ccrit = 0.4% by mass of binder (assumptions, Annex A).
Products and implementation
Table D.17 Cameroon imports by HS line, US$ million (Figure 9.1)
| HS line | 2019 | 2020 | 2021 | 2022 | 2023 |
|---|---|---|---|---|---|
| HS 7213 wire rod | 40.6 | 55.6 | 74.0 | 26.6 | 8.1 |
| HS 7216 sections | 16.8 | 29.6 | 29.1 | 26.2 | 26.3 |
| HS 7214 bars incl. rebar | 3.7 | 12.5 | 9.2 | 6.9 | 3.3 |
| HS 7217 wire | 2.8 | 4.0 | 5.3 | 6.3 | 5.1 |
Source: UN Comtrade public API, Cameroon reporter data [S52].
Table D.18 Indicative implementation calendar (Figure 10.1)
| Measure | Start | End | Lead |
|---|---|---|---|
| R1 Publish NC 236 essentials and certified-mill list | 2027 Q1 | 2027 Q2 | ANOR |
| R2 Certification with surveillance and audit testing | 2027 Q1 | 2028 Q2 | ANOR, mills |
| R3 Market surveillance at merchants, published results | 2027 Q2 | 2030 Q4 | ANOR, MINCOMMERCE |
| R4 Price homologation per tonne, not per bar | 2027 Q1 | 2027 Q3 | MINCOMMERCE |
| R5 Certified rebar clause in public works contracts | 2027 Q1 | 2027 Q4 | MINMAP, ARMP |
| R6 Site acceptance testing tied to building permits | 2027 Q3 | 2029 Q2 | MINHDU, councils |
| R7 Accredited testing capacity in each main city | 2027 Q3 | 2029 Q4 | ANOR, labs |
| R8 Training for masons, foremen and engineers | 2027 Q1 | 2030 Q4 | Industry, schools |
| R9 Durability rules for the coast (cover, mixes) | 2027 Q3 | 2028 Q4 | MINHDU, ANOR |
| R10 Annual public report on rebar conformity | 2028 Q1 | 2030 Q4 | ANOR |
Source: Cameroon Steel indicative calendar; quarters approximate.
Sources cited in this chapter
Bracketed markers refer to these sources; the full list is in the annex. Full list of sources
- S36EN 1992-1-1:2004 Eurocode 2: Design of concrete structures, Part 1-1: General rules and rules for buildings (with corrigenda). European Committee for Standardization (CEN), 2004.eurocodes.jrc.ec.europa.eu/EN-Eurocodes/eurocode-2-design-concrete-str…
- S29Probabilistic Model Code, Part 3: Resistance models, 3.2 Static properties of reinforcing steel. Joint Committee on Structural Safety (JCSS), 2001 edition.jcss-lc.org/publications/jcsspmc/rebar.pdf
- S30EN 1992 Eurocode 2: Design of concrete structures (J. Walraven), workshop "Eurocodes: background and applications", Brussels, 18 to 20 Feb 2008. European Commission (DG Enterprise and Industry, Joint Research Centre), Feb 2008.eurocodes.fi/wp-content/uploads/1992/sahkoinen1992/EN-1992.pdf
- S31Certificat N° B03/176 rév. 16, aciers pour béton armé, NF A 35-080-1 nuance B500B (fiche descriptive and caractéristiques certifiées). Association Française de Certification des Armatures du Béton (AFCAB), AFNOR Certification, 6 Jun 2025.feralpi-stahl.com/sites/default/files/media/certifications/NF%20AFCAB-…
- S38BS 4449:2005+A3:2016 Steel for the reinforcement of concrete. Weldable reinforcing steel. Bar, coil and decoiled product. Specification. British Standards Institution (BSI), 2016.boutique.afnor.org/en-gb/standard/bs-44492005-a32016/steel-for-the-rei…
- S32Technical specification SPF400 rev. 12, Rebars B500 (chemical, mechanical and dimensional requirements under EN 10080 and national standards). Ferriere Nord S.p.A. (Pittini group), 14 Sep 2021.pittini.it/wp-content/uploads/Pittini-Group-Reinforcing-Steel-Bars-B50…
- S53Production: les acteurs en présence. Cameroon Tribune, 11 May 2026.cameroon-tribune.cm/article.html/76600/fr.html/details_2
- S28Mechanical strength variability of deformed reinforcing steel bars for concrete structures in Ethiopia. Scientific Reports 12, 2600. T. Achamyeleh, H. Çamur, M. A. Savaş, A. Evcil; Nature Portfolio, 2022.doi.org/10.1038/s41598-022-06654-1
- S19Assessment of Deviation in Quality of Steel Reinforcing Bars Used in Some Building Sites in Cameroon. World Journal of Engineering and Technology, 11(4), pp. 917 to 931. P. C. Bame, B. E. Yamb, B. Ndigui; Scientific Research Publishing, 2023.doi.org/10.4236/wjet.2023.114061
- S11Fer à béton: les producteurs acceptent une baisse des prix. EcoMatin, 23 Oct 2023.ecomatin.net/fer-a-beton-les-producteurs-acceptent-une-baisse-des-prix
- S50POWER climatology API, parameters T2M, RH2M, PRECTOTCORR, 1991 to 2020, at Douala, Kribi, Yaoundé and Garoua. NASA Langley Research Center.power.larc.nasa.gov/api/temporal/climatology/point?parameters=T2M,RH2M…
- S52UN Comtrade public API, Cameroon (reporter 120), imports and exports by HS line, chapters 72 and 73, 2019 to 2023. United Nations Statistics Division.comtradeapi.un.org/public/v1/preview/C/A/HS?reporterCode=120&period=20…
Cite this chapter
Cameroon Steel (2026). Safer buildings need rebar that meets its declared grade. White paper 10, annex D: Data tables behind the exhibits. CS-WP-10. https://www.cameroon-steel.com/en/library/quality-steel/annex-data/
Source