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Sep. 21, 2026
Concrete Admixture Technical Guide · No. 07
A high-rise building required C50 concrete for its core tube. This case study shows the mix, the admixture dosage and the results. All admixture dosages are by solid content; both admixtures are flake PCE (polycarboxylate superplasticizer).
| Requirement | Target |
| Initial Slump | ≥ 180 mm |
| Slump loss after 2 hours | ≤ 30 mm |
| Strength | High, pumpable, low bleeding |
| Air Temperature | About 30 °C |
| Transport Time | 40 minutes |
| Material | Specification |
| Cement | P·O 52.5 |
| Coarse Aggregate | 5–20 mm granite, crushing value ≤ 10% |
| Fine Aggregate | River sand, fineness modulus 2.6–2.8, clay content < 1% |
| Fly Ash | Grade I, 10% of binder |
| Slag Powder | S95, 15% of binder |
| Admixtures | PC 6010F (flake, water reducer) + PC 6020RT (flake, high slump retention) |
| Material | Dosage | Note |
| Cement P·O 52.5 | 375 | Total binder 500 |
| Fly Ash (Grade I) | 50 | 10% of binder |
| Slag (S95) | 75 | 15% of binder |
| Water | 155 | Water-binder ratio 0.31 |
| Sand (river) | 720 | 40% sand ratio |
| Crushed stone (5–20 mm) | 1080 | Graded |
| PC 6010F (flake) | 1.2 | 0.24% of binder, by solid |
| PC 6020RT (flake) | 0.3 | 0.06% of binder, by solid |
Total binder = 375 + 50 + 75 = 500 kg/m³.
Flake PCE is about 100% solid, so the dosage is direct — no conversion is required.
| Admixture | Dose | Role |
| PC 6010F | 0.24% of binder (1.2 kg/m³) | Water reduction |
| PC 6020RT | 0.06% of binder (0.3 kg/m³) | Slump retention |
| Total | 0.30% of binder | Ratio 4:1 (6010 : 6020RT) |
The ratio in this example is 4:1, but it normally ranges from 9:1 to 3:1, depending on how long the slump must hold and on the cement. Test to find it.
| Step | Detail |
| Mixing | Forced mixer, 3 minutes |
| Transport | Slow agitation in the truck |
| Slump | Initial 205 mm; after 2 hours, 180 mm (loss 25 mm, within limit) |
| Adjustment | If slump loss runs high, add 0.1% to 0.2% more PC 6020RT |
| Test | Value | Requirement |
| 28-day compressive strength | 62.5 MPa | ≥ 50 MPa |
| Initial Slump | 205 mm | ≥ 180 mm |
| Slump after 2 hours | 180 mm | ≥ 150 mm |
| Bleeding Rate | 0.8% | ≤ 1% |
| Chloride Content | 0.02% | ≤ 0.06% |
PC 6010F provides the strength; PC 6020RT maintains the workability. They work together.
The low water-binder ratio (0.31) is achievable because of the high-range water reducer.
Fly ash and slag improve workability and reduce thermal cracking.
Flake PCE is dosed by solid content — simple and exact, with no liquid-strength guesswork.
Test the PC 6020RT ratio first; the correct ratio depends on the cement and the required retention time.
In hot weather, use chilled water (≤ 20 °C) to control the mix temperature.
For a complete overview of every concrete admixture and when to use each, read Concrete Admixtures: The Complete Guide.
To choose between the PCE models, read Which Polycarboxylate Superplasticizer (PCE) Should You Choose?.
To learn how a high slump-retention PCE works, read What Is a High Slump-Retention Polycarboxylate Superplasticizer (PCE)?.
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