THE FIRST POUR

A field guide to concrete — ratio, sound, and timing. From the Gulf to the slab.

I. THE RATIO

Mix 1:2:3 — One part cement, two parts sand, three parts aggregate. Water to cement ratio: 0.45 ± 0.05. This is the law.

Component Part by Weight Volume Equivalent Source
Cement 1.0 1 sack (94 lb) Q45190
Sand 2.0 2 cu ft ASTM C33
Aggregate 3.0 3 cu ft (¾" ACI 211.1
Water 0.45 5–6 gal Q283

NOTE: Cement (Q45190) is a hydraulic binder made from limestone and clay. Water (Q283) is H₂O — the activator. Add water LAST. Always.

II. THE SOUND

"Listen to the mix."

Wet concrete sings a low hum — like distant thunder rolling over the bay. Too dry, and it crackles like dead leaves. Too wet, and it slaps like mud on a tin roof.

Target sound: A thick whisper. The consistency of heavy cream, not milk.

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HUMIDITY CHECK
Above 80% RH? Reduce water by 0.03. Below 40%? Mist the aggregate first.
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WIND SPEED
Over 15 mph? Cover the mix immediately. Evaporation steals the cure.

III. THE TIMING

From first water contact to final set: 90 minutes at 75°F. Temperature shifts the clock.

0–10 min
MIXING — rotate the drum. Watch for clumps.
10–25 min
TRANSPORT — keep agitation. No stops longer than 2 minutes.
25–45 min
POUR — continuous flow. Rod every 12 inches.
45–60 min
FLOAT — wood trowel only. Steel comes later.
60–90 min
SEED — cover with burlack. Begin cure.

TEMP CORRECTION: For every 5°F above 75°F, subtract 5 minutes from each phase. Below 75°F? Add 8 minutes per 5°F.

IV. THE NEIGHBOR'S HAND

This guide stands on shoulders:

Alvester's kiln work teaches the same breath-between-heat principle. His temperature curves inform our timing chapter.

V. THE IMAGE

See the mix in motion:

License-clean media fetched on demand.

VI. NEXT STEPS

This guide is Chapter One. The next pours will carry:

  • Rebar spacing calculations — grounded in steel yield strength (Q1144626).
  • Slab thickness by load — residential vs. industrial footprints.
  • Cure monitoring — humidity sensors and the thermal signature of setting.

Each chapter a deeper dive. Each pour a stronger foundation.