Cement: Setting

Definition – Measurement

Influencing parameters

Stiffening

Setting Definition – Measurement

Cement setting definition

Setting

opassage from liquid or plastic state to a solid state

Setting time

o time required for a cement paste, gauged to a standard consistency, to reach a state of rigidification determined by the penetration of a standard needle

Standard consistency

o paste which gives a specified resistance to the penetration of a standard probe

the required water for such a paste is determined by penetration tests on pastes made with different quantities of water

Cement setting

Setting influencing parameters

Let’s brainstorm …

–W/C

–Fineness

–C3S level (C3S/C2S)

–C3A level

–FCaO

–Sulphatation (% – nature)

–Alkaline sulphates

–Mineralizer agent

–Temperature

–Weathering / ageing

–Admixtures

Free lime

Level of C3A

–Small study

o Lafarge Corporation study

–Yearly average 1992-93

o setting time (min.) =

-44 x (%f – CaO) – 0,12 x (m2 / kg) – 2,22 x (% C3A) + 216

o r2 = 0,61

–Inter-lab test – Average 1967-93

o setting time (min.) =

-25,5 x (%f – CaO) – 0,199 x (m2 / kg) – 3,44x (% C3A)- 20,4 (% Na2O eq) + 266

r2 = 0,44

Mineralizer agent

Water requirement W/C

Cement fineness

Temperature

Ageing

Stiffening

Stiffening characterization

Stiffening: determination of causes

Analysis of gauging liquor

Ettringite analysis

Nature of sulfates

X-ray diffraction after silicate dissolution

Chemical analysis