Concrete & Admixtures
Admixture Dosage Calculator
Pick the admixture and set the dosage as a percentage by weight of cement. This works from each product’s published dosage band, converts it to kilos and litres per cubic metre, per batch and per truck load, and rounds up to whole drums.
Your mix
Set the binder and volume, pick the admixture, then dial the dose.
kg/m³
kg/m³
m³
m³
SG
What this assumes
- Dosage figures come from the technical data published for the product you select, expressed as a percentage by weight of cement (cementitious material), and the exact sentence is shown under every result. The provenance tag says whether it is a manufacturer figure or, for the few starting-point entries, an indicative one to confirm by trial.
- Admixture is dosed on the binder. If you replace part of the cement with fly ash, GGBS or silica fume, the dose is calculated on cement + SCM together — turn on the supplementary cementitious material control so it is not under-dosed on cement alone.
- The dosage band is the manufacturer’s window, not a single number. The tool defaults to the typical figure; move it and it flags any value outside the published low–high. Confirm the working dose by trial mix — water demand, ambient temperature and cement chemistry all shift it.
- Litres are derived from an assumed specific gravity of 1.2, typical for a water-based admixture but published for almost none of them. The kilogram figure is exact — it is a weight of cement; treat the litre figure as indicative and edit the SG if the datasheet gives a density.
- Drum counts round up to whole drums and prefer the largest drum that does not overshoot. Overdosing to finish a part-used drum is not a saving: excess superplasticiser causes segregation, retardation and bleeding.
Where these figures come from. Dosage ranges, pack sizes and the source sentence are parsed from the technical data published for each of the 120 doseable products and are shown verbatim with every result. No India-specific percentage-of-cement dosage tool exists elsewhere — generic calculators ask for millilitres per 100 kg, which is the figure you opened this to find. Where a datasheet gives a starting point rather than a full range, the tool marks it and asks you to confirm by trial before it goes on a delivery note.
Questions
Is admixture dosage a percentage of the cement or of the concrete?
Of the cement — or, more precisely, of the cementitious material: cement plus any fly ash, GGBS or silica fume in the mix. It is never a percentage of the whole concrete or of the water. A dose of 1% on 350 kg/m³ of binder is 3.5 kg of admixture in every cubic metre.
How do I turn a percentage of cement into millilitres per 50 kg bag?
Take the dose per m³ in kilograms, divide by the number of bags of cement per m³, then divide by the specific gravity to get litres and multiply by 1000 for millilitres. This tool does the per-m³ and per-batch conversion for you and shows both kilograms and litres.
Should I dose on cement only, or include the fly ash and GGBS?
Include them. Admixtures act on the whole cementitious system, so the dose is figured on cement + SCM. Dosing on the OPC alone under-doses a blended mix and you lose the slump or strength you were paying for. Switch on the supplementary cementitious material control.
What specific gravity should I use to get litres from the kilograms?
Most water-based admixtures sit around 1.1 to 1.2, and 1.2 is the default here. But it is rarely on the datasheet, so the litre figure is indicative. The kilogram figure is exact — it is a straight weight of cement — so order and dose to the kilograms where you can.
What happens if I overdose the admixture?
Overdosing a plasticiser or superplasticiser typically causes excessive retardation, segregation, bleeding and, at the extreme, a failure to set. It is not a way to stretch a drum. Stay inside the published band and settle the working dose with a trial mix on the actual materials.
Can I put this dosage straight into a mix design or BOQ?
Use it to size a delivery and to sanity-check a mix, then confirm the working dose by trial mix and against the current datasheet before it is committed. Formulations, pack sizes and the cement on site all move consumption, and the trial mix is the figure that counts.
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