We're grouting a reinforced CMU wall that's 12 feet tall.

No, you cannot legally or practically fill a 12-ft wall in a single pour. TMS 602 (ACI 530.1) Article 3.5 B limits maximum pour height to 4 ft (1.2 m) for standard grout lifts. A 12-ft pour generates ~750 psf lateral pressure at the base—enough to blow out face shells, displace reinforcement, or collapse the wall.

Legal/Code-Compliant Procedure (TMS 602 Art. 3.5):

1. Lifts: Place grout in 4-ft maximum lifts.
2. Time Limit: Complete each lift within 1.5 hours of batching (Art. 3.5 C).
3. Consolidation: Mechanical vibration required for each lift (Art. 3.5 D). Insert vibrator 6–8 in. into previous lift to knit lifts. Re-vibrate after initial settlement (5–10 min).
4. Cleanouts: Required for pours > 4 ft high (Art. 3.5 A). Install at base of every pour (every 4 ft) to remove mortar droppings, check alignment, and verify consolidation. Close before next lift.
5. Grout Spec: Use coarse grout (3/8" aggregate) per ASTM C476. Slump 8–11 in. for vibration. Do not exceed 11 in. slump—segregation risk.
6. Reinforcement: Verify vertical bars are tied/positioned per shop drawings before grouting. Horizontal bond beams must be grouted solid.

Practical Sequence:

• Day 1: Lay block to 4 ft. Install cleanouts. Vibrate Lift 1.
• Day 2: Lay next 4 ft. Cleanouts at 8 ft. Vibrate Lift 2 (penetrate Lift 1).
• Day 3: Lay top 4 ft. Final cleanouts. Vibrate Lift 3.

Inspector will check: Cleanout presence/closure, lift heights, vibrator on-site, grout tickets (slump/time), rebar position.

Bottom line: Three pours over three days. Skipping lifts or cleanouts = failed inspection and structural risk.

No, you cannot fill a 12-foot-tall reinforced CMU wall in one shot from the top and expect a legal, structurally sound grout fill. This violates industry standards and building codes.

Why it’s not allowed:

• ACI 530/ASCE 5/TMS 402 (Building Code Requirements for Masonry Structures) and ASTM C476 require grout to be placed in lifts not exceeding 5 feet in height for walls over 4 feet tall. For a 12-foot wall, this means minimum three lifts (e.g., 4 ft each).
• Pouring from the top in one continuous pour risks:
• Voids or honeycombing due to grout not flowing fully to the bottom.
• Segregation of aggregates and water, weakening the grout.
• Inadequate consolidation — you cannot properly rod or vibrate grout at the bottom if poured from the top.
• Hydrostatic pressure may blow out weak joints or cause blowouts at the base.

To do it legally and correctly:

1. Use grout lifts ≤5 ft high (per TMS 602, Section 3.3.B).
2. Place grout from the bottom up using a grout pump or bucket and chute — never pour freely from the top.
3. Consolidate each lift with a mechanical vibrator or rodding (¾-inch diameter rod) as grout is placed, re-rodding after initial settlement.
4. Wait for initial set (typically 1–4 hours, per grout manufacturer) before placing the next lift to avoid cold joints and ensure bonding.
5. Use a grout mix meeting ASTM C476 (Type Fine or Coarse, depending on bar spacing) with slump of 8–11 inches for pumpability and flow.
6. Clean out debris from cells before grouting — mortar fins, debris, or misaligned rebar block flow.
7. Inspect and verify alignment, cleanliness, and brace stability before each lift (per TMS 602, Section 1.4.B).

Bottom line: One-shot top pour is prohibited, unsafe, and will likely fail inspection. Use bottom-up lifts with consolidation. If you lack equipment or experience, hire a licensed mason or grouting specialist — improper grout compromises structural integrity and is not worth the risk. Always consult the project’s structural engineer and local building official for site-specific approval.