The Mix Bench — water, cement & workability

Set your mix

Start from a preset used for common simple-form grades, then experiment.

Water : cement ratio 0.55

0.35 · dry & strong0.90 · wet & weak

Aggregate share (by volume) 67%

55% · paste-rich80% · boney & harsh

Mixing time 3.0 min

0.5 min · patchy8 min · overworked

💡 Site intuition: water is what makes fresh concrete flow — but every drop beyond what the cement needs leaves tiny voids as it dries out. Wet mix now, weak slab later.

Slump test — workability

The cone is filled, lifted, and the concrete slumps. How far it drops tells you how workable the mix is.

Predicted 28-day strength

Risk flags

Your mix docket — prove all five

Explore until you’ve ticked every line. This is how the trade-off sinks in.

Apply a grade preset (N20, N25 or N32)

Build a strong mix — 32 MPa or more

Trigger the too-wet warning (weak, prone to cracking)

Trigger a segregation warning (stones and water part ways)

Dial in a balanced hand-pour mix: N20–N25 grade, slump 50–100 mm, no warnings

0 of 5 ticked

Signed off Docket complete. You’ve seen the core rule of KE9 for yourself: water buys workability and costs strength — get the proportions right and the mix does both jobs.