Conventional assembly parameters: sourcing round 1 (AR-74)¶
Status: sourcing round 1, Session 32 (2026-09-28). No catalog record carries these values yet.
They integrate in PR-4 (feat/p1-conventional-assemblies) and, for densities, in PR-2's
volume → mass seam. See the design §5.1 and
action register AR-74.
These are quantity parameters and densities, not impact factors. They gate on the catalog provenance rule (decision #28: citation, per-parameter Axis-2 verdict, Weidema pedigree), not on the seed-EPD gate. Pedigree scores follow Weidema & Wesnæs (1996): 1 is best, 5 is worst. They are listed in the order R / C / T / G / Te: reliability, completeness, temporal, geographical, further technological correlation.
1 · Block format: Senegal market¶
The Dakar-market hollow block (parpaing, agglo creux) is 500 × 200 mm on the face. That is a coordinating size: a 490 × 190 mm block plus a 10 mm joint. It comes in 15 cm and 20 cm widths, class B40 (4 MPa).
| Evidence | What it says | Use |
|---|---|---|
| CYPE Senegal price generator, GMB010 / GMB070 / GMB080 | 500×200×200 hollow block "selon NF EN 771-3", B40, 10 mm joints, mortar 250 kg cement/m³, 1:6 | Cross-check only (licence below) |
| 3M Distribution (Dakar), "Zone Dakar-500 Agglos 15x20x50" | 15×20×50 hollow, 16 kg, B40 | Block mass, weak |
| TCB SARL (Bamako), Sunu Équipement | 15×20×40 hollow blocks also on the market | Alternative format |
The block format is therefore a stated parameter on the record (block_length,
block_height, joint), not a hidden constant. Blocks per m² changes from 10.0 to 12.5 with it.
2 · Wall parameters¶
| Parameter | Value | Unit | Source | Vendor? | R/C/T/G/Te | Justification |
|---|---|---|---|---|---|---|
| Blocks per m², 500×200 format | 10.0 (before breakage) | u/m² | Geometry: 1 / ((0.49 + 0.01)(0.19 + 0.01)). Cross-check: CYPE GMB070/GMB080 give 10.000 U/m²; GMB010 gives 10.500 including special pieces and breakage | Yes, as project arithmetic | 2/2/1/1/2 | A first-principles count that matches the Senegal cost database exactly. |
| Blocks per m², 400×200 format | 12.5 | u/m² | Same geometry | Yes | 2/2/1/2/2 | Only when the project specifies 40 cm blocks. |
| Mortar per m², 20 cm wall | 0.0138 | m³/m² | Full-bed joint geometry, 10 mm joints: bed 5 m × 0.20 × 0.01, plus 10 head joints × 0.19 × 0.20 × 0.01. Cross-check: CYPE GMB010 has 3.528 kg cement at 250 kg/m³, giving 0.0141 m³/m² (Δ = 2.3 %) | Yes, as project arithmetic | 2/3/1/2/2 | Geometry with an independent Senegal cross-check. Assumes full bedding, which is what CYPE assumes. |
| Mortar per m², 15 cm wall | 0.0104 | m³/m² | Same formula, t = 0.15 | Yes | 2/3/1/2/2 | No direct Senegal figure for this width. |
| Mortar mix | 250 kg cement/m³, 1:6 | — | CYPE Senegal GMB010, clauses techniques | No (cite only) | 3/3/1/1/3 | The only Senegal-specific mix found. A permitted source is still needed (AR-74(b)). |
The mortar formula generalises to
V = t · j · (1/(H + j) + n · H), where n is blocks per m², H the actual block height,
t the wall thickness and j the joint thickness.
3 · RC roof slab rebar: BLOCKED¶
| Candidate | Value | Why it is not a default |
|---|---|---|
| CYPE Senegal Dalle pleine | 21 kg/m² (22.05 with 5 % waste) on a 24 cm slab, about 87.5 kg/m³ | Wrong thickness. It comes from a parametric commercial price generator, not a design, and it cannot be vendored. |
| EN 1992-1-1 §9.3.1.1 minimum steel (A_s,min), 150 mm slab, C25/30, B500, d ≈ 120 mm | ≈ 162 mm²/m each way, about 17 kg/m³ (bottom mesh only) | This is a lower bound, not a typical value. Keep it as a test assertion: any sourced value must be ≥ 17 kg/m³. |
| Office-slab optimisation literature (e.g. Paknahad et al. 2025, doi:10.3390/su17198662, CC BY) | — | Office loads with 4–14 m spans; the context doesn't match. |
| Aggregators (One Click LCA help pages, blogs) | 60–90 kg/m³ | No primary source. Not admissible. |
Keur Songho struct.rc-350 |
100 kg/m³ | Forbidden (AR-14). |
Route to close: a structural engineer does a worked EC2 design of a 150 mm single-storey
roof slab at the estimator's span, recorded as named EXPERT-JUDGEMENT (who, date, basis). AR-74
already allows this for (c).
4 · Densities¶
| Material | Value | Unit | Source | Vendor? | R/C/T/G/Te | Justification |
|---|---|---|---|---|---|---|
| Normal-weight concrete, plain | 2300 (2300.333) | kg/m³ | ÖKOBAUDAT "Ready-mix concrete C25/30", a71e60a5-b64b-4715-ae8a-c8c8819149d2 v20.26.070, reference-flow mass per m³ |
Yes (DL-DE-BY-2.0) | 2/2/1/4/2 | Use the plain density because rebar mass is added separately. The reinforced 25 kN/m³ would count the steel twice. EN 1991-1-1's 24 kN/m³ (about 2400 by the ISO 9194 convention) brackets it. |
| Reinforcing steel | 7850 | kg/m³ | EN 1992-1-1 §3.2.7(3), mean density | Yes (single cited value; standard text not reproduced) | 1/1/1/2/1 | A physical property that doesn't vary by location. It is a better citation for AR-23 than EN 10025. |
| Cement mortar | 1900–2300 (range) | kg/m³ | EN 1991-1-1 Annex A, Table A.1 (19–23 kN/m³), as confirmed by JRC Eurocodes Handbook 3 | Range cite only | 2/3/2/3/3 | ÖKOBAUDAT "Cement mortar" (96171066-…) declares no density. A point value would need EXPERT-JUDGEMENT. |
| Cement plaster | 1900–2300 (as cement mortar) | kg/m³ | Same. ÖKOBAUDAT has only lime-cement plaster, at 1800 kg/m³ | Range cite only | 2/3/2/3/3 | A cement-sand render is a cement mortar. |
| Block concrete, net | 2000 | kg/m³ | ÖKOBAUDAT "Concrete masonry brick; 2000 kg/m3", 2cdcffc6-84e9-4238-b8af-beebabea9a2d v20.26.070 |
Yes (DL-DE-BY-2.0) | 2/3/1/4/3 | Gives block mass only together with a void fraction, which is unsourced. |
| Hollow block, gross, 15×20×50 | ≈ 1067 (16 kg / 0.015 m³) | kg/m³ | 3M Distribution Dakar product page | No (retailer, no licence) | 4/5/1/1/2 | PROVISIONAL. One unverified retailer claim. |
| Hollow block, gross, 20 cm | — | — | none found | — | — | BLOCKED. |
Mortar and plaster density may not be needed. The existing finish.cement-plaster-16
recipe already breaks plaster down into cement and sand. If the CMU records do the same with
mortar (the AR-74(b) mix), mass comes from composition. The two range rows then drop out, and so
does their EXPERT-JUDGEMENT step.
Block mass per unit (kg/block) is the better record parameter than hollow-block density. It can be measured directly, and AR-74(a) asks for it anyway. A Dakar producer datasheet or a weigh-test would close both widths.
5 · Licences¶
| Source | Terms | Verdict |
|---|---|---|
| ÖKOBAUDAT | DL-DE-BY-2.0 (THIRD_PARTY.md §3) | Vendorable with attribution |
| EN 1991-1-1, EN 1992-1-1 | © CEN; purchase required | Cite single values; don't reproduce tables (same pattern as EN ISO 52016-1) |
| CYPE Générateur de prix (Senegal) | Legal notice: "usage personnel et non commercial"; no passing reproduced content to third parties | Not vendorable. Cross-check citation only |
| 3M Distribution, TCB SARL, Sunu Équipement | Retail pages, no licence stated | Cite only; weak evidence |
No Senegalese national standard (ASN / NS) for block dimensions or slab reinforcement was found online. ASN standards appear to be paywalled.
6 · What this unblocks¶
| AR-74 item | State after round 1 |
|---|---|
| (a) blocks per m² | Sourceable. Geometry formula with the format as a parameter |
| (a) block mass / composition | 15 cm PROVISIONAL (retailer); 20 cm BLOCKED; composition BLOCKED |
| (b) mortar m³/m² | Sourceable. Geometry formula, cross-checked against CYPE |
| (b) mortar mix | BLOCKED for vendoring (CYPE is cite-only) |
| (c) slab rebar | BLOCKED. Needs structural-engineer EXPERT-JUDGEMENT |
| Densities for PR-2's seam | concrete 2300 and steel 7850 vendorable; mortar/plaster only if composition is not used |
Sources¶
- CYPE Ingenieros, Générateur de prix — Sénégal: GMB010, GMB070, GMB080, Dalle pleine (senegal.prix-construction.info), accessed 2026-09-28. Legal notice: shop.cype.com/fr/mentions-legales/.
- 3M Distribution, "Zone Dakar-500 Agglos-15x20x50" (3mdistribution.net), accessed 2026-09-28.
- TCB SARL, "Parpaing creux 15x20x40" (tcbsarl.com), accessed 2026-09-28.
- Holický et al., Implementation of Eurocodes, Handbook 3: Action effects for buildings, Leonardo da Vinci CZ/02/B/F/PP-134007 (eurocodes.jrc.ec.europa.eu).
- EN 1991-1-1:2002, Annex A; EN 1992-1-1:2004, §3.2.7 and §9.3.1.1.
- ÖKOBAUDAT (soda4LCA API), datasets
a71e60a5-…,96171066-…,dca9f05c-…,2cdcffc6-…, v20.26.070, accessed 2026-09-28.