Pumped Concrete: Distances, Equipment and Site Rules

Bringing ten cubic metres of concrete to a building's sixth floor with no truck access, pouring a 300 m2 slab in one morning, crossing a garden without damaging the existing paving: in all these cases the answer is pumping — concrete travels through a pipe under pressure. But travelling concrete is tired concrete: friction, pressure, segregation and blockage risks. Pumping well means choosing the right machine, preparing the mix and the line, and following a few simple rules that separate a smooth pour day from a site at a standstill.

The machines: boom or line

Two big families equip Moroccan sites. The boom pump (truck-mounted) carries its telescopic mast folded on its chassis: ten minutes of setting up, the boom unfolds and pours straight from the truck to the point of use — common booms cover about twenty metres of reach, large machines exceed 50 m in maximum configuration. It is the default choice whenever access exists: fast, clean, no pipeline to lay. The stationary pump stays on the ground and feeds a pipeline assembled towards the formwork: indispensable for pouring inside a dense rebar cage, at the bottom of an excavation, or on floors the boom cannot reach — but it demands building the line, holding it and cleaning it.

The crane-handled skip remains the third way — slow, but sometimes the only option on very congested sites. The hire company sizes it with you: that is their trade, and yours is to give them the right information (access, distances, lift, volumes per hour).

What pumping changes in the mix

A pumped concrete is not any concrete tipped into a pipe. Three requirements return systematically. Enough fines — cement + fillers + fine sands: the paste that lubricates the line, with a total fines content commonly targeted around 350-400 kg/m3; without fines, the concrete blocks. A calibrated slump — too stiff and friction wins; too fluid and segregation lurks: the typical window sits between 120 and 180 mm of slump, held for the whole transport duration. A dosed superplasticiser — it alone holds workability at constant water (the admixtures guide details these families); the temptation to “loosen” the mix with water costs MPa and shifts the formula during the day. The cement class follows the strength target: CPJ 45 for everyday pumped concrete, CPJ 55 when the mix climbs in demands — and in both cases, a consistent batch, because pumping amplifies cement variations (setting that moves, admixture that drops off).

Distances and losses: the line is computed

Sizing is done in equivalent linear metres: every vertical metre and every bend costs more pressure than a horizontal metre. The operators' rules of thumb: one metre of vertical lift counts as about three horizontal metres, a 90° bend as about three metres too. A line of 40 m horizontal with 12 m of lift and four bends thus “weighs” the equivalent of 40 + 36 + 12 = nearly 90 m — to compare with the pump's capacity and the total truck-to-formwork distance. When the equivalent exceeds the machine's sensible range, you move the pump closer, simplify the line, or change machines: that is a pre-site computation, not a discovery at the first batch.

The day-of protocol

On pour morning, the checklist that prevents 90% of incidents: clean lines (a badly rinsed tube hides a dry plug), checked couplings (a slurry leak mid-pour creates a plug downstream), launching cushion — start with a mortar batch or a separation ball to grease the line before the concrete, pour plan respected (direction of travel, positioned construction joints, never an improvised joint mid-slab), and pump-truck communication for the rate. During pumping: steady rhythm, no long stops (concrete resting in the line becomes a live plug), watching the arriving concrete — concrete arriving segregated (paste on top, aggregates apart) signals a mix or a rate to fix immediately. End of shift: full rinse with water recovery, dismantling and tube inspection.

The costly mistakes

• Sizing the pump by eye: equivalent length not computed, undersized machine.
• Loosening the mix with water to “flow better”: the line gains, strength loses.
• Skipping the launching cushion: the first batch rubs dry and blocks.
• Unjustified long stops: every pause beyond a few dozen minutes endangers the line.
• A line badly cleaned the day before: the dry plug waits for tomorrow's first concrete.
• A joint mid-slab because the schedule slipped: the pour plan is to be respected, period.

What DAM supplies — and does not

Pumping is the trade of ready-mix plants and pump hirers — not ours, and we prefer saying so. Our role starts upstream: supplying the consistent, documented cement (CPJ 45 and CPJ 55 compliant with NM 10.1.004, certificate per batch) that plants and sites build their pumped mixes on, and helping you frame volumes coherently with the chosen pumping capacity. If your site pumps site-mixed concrete, we deliver cement in bags, big bags or bulk to match the rate; if you buy pumped ready-mix, our dedicated page points you there. Describe the site — volumes, rate, schedule — and we align the cement logistics.

In summary

Pumping is prepared: the machine is chosen by equivalent distance (vertical and bends counted triple), the mix by fines, calibrated slump and superplasticiser, the day by the cushion, a steady rate and the rinse. CPJ 45 for everyday, CPJ 55 for demanding, and never added water to “save” a batch — pumping discipline is exactly concrete discipline: prepared, calibrated, executed without improvisation.