Application & technical guidance
Cement & PCE Compatibility: Slump-Loss Checklist
Investigate poor flow and slump loss with a controlled checklist for materials, dose basis, water, temperature and trial records before changing PCE grades.
Treat slump loss as a symptom, not a diagnosis
A loss of consistency does not by itself prove that the PCE grade is incompatible. NRMCA describes changes in available water, aggregate absorption, cement hydration and evaporation as contributors to slump loss. Setting time is a separate property. NRMCA: Slump Loss of Concrete.
The practical question is whether a candidate grade gives repeatable results with the actual binder, aggregate and production process. Use the sequence below to separate a materials change from a dosing or production change. It is a troubleshooting worksheet, not a standard acceptance test.
1. Establish what changed
| Observation | Check first | Record for comparison |
|---|---|---|
| Poor flow from the first reading | Weighed product, stated dose basis, total water and mixing record | Grade/lot, product mass, binder mass, water correction and sequence |
| Initial flow acceptable, later reading low | Elapsed time, concrete temperature and delivery conditions | Time-stamped results from batching through the required placing window |
| Different response after a material delivery | Binder and aggregate sources, certificates and moisture records | Old/new lot identity and comparable trials |
| More flow accompanied by instability | Whole-mix behavior rather than slump alone | Bleeding/segregation observations, air, density and strength results |
Use the dosage guide to check units before interpreting the outcome. A percentage of supplied liquid cannot be compared directly with a percentage of dry solids.
2. Write a controlled comparison
- Reference: record the current approved material combination and its actual test results.
- Candidate: identify the proposed grade and batch. Obtain its current application instructions.
- Variable: change one planned factor, such as the grade or a defined dose step, while documenting everything else.
- Timing: choose measurement points that cover the required use window. Record actual times, not only labels such as “one hour”.
- Repeatability: repeat a promising result before extending the evaluation to production conditions.
NRMCA’s quality-control guidance includes fresh-concrete checks such as slump, air and density alongside materials and strength control. Use project-appropriate test methods and acceptance criteria. Quality-control reference.
3. Include temperature and the full performance target
High initial concrete temperature together with high ambient temperature can increase slump loss. NRMCA temperature guidance supports recording the concrete temperature as well as the weather.
A laboratory comparison at one temperature cannot establish suitability for every season. Where the operating range is important, agree representative trial conditions with the producer. Record setting behavior and strength at relevant ages as well as fresh consistency; one successful flow measurement is not the complete result.
If a paste or mortar screen is used to shortlist a material, identify it as screening evidence. Confirm the selected route in the intended concrete or mortar system before approval.
4. Choose the next action from the evidence
- Record discrepancy found: correct the documented weighing, unit or water-accounting error before comparing grades.
- Retention is the unresolved target: discuss a retention-oriented grade and verify the required placing window.
- Materials changed: submit both material identities and comparable results with your PCE grade request.
- Result remains unexplained: request a technical review rather than assuming that increasing dose will solve the problem.
Do not use this guide as permission to add water or redose a delivered load. Any adjustment must follow the approved project procedure and the product instructions.
Record every addition when reviewing a mixing trial
A short mixing demonstration can help you see the addition sequence. In Sika Australia's external ViscoCrete 190 SC demonstration, the inspected frames around 0:58 and 1:54 show liquid being poured into an operating mixer. This is Sika's product demonstration, not an AdmixChem trial or evidence of equivalent product performance.
For your own comparison, make the visual record traceable to the batch sheet:
- Label each addition with the material identity, weighed quantity and actual addition time. A clear liquid's identity or mass cannot be established from appearance alone.
- Record the mixing interval before each sample, together with the water and admixture already added.
- Attach the measured consistency result and its sampling time to the clip. Follow the approved test method; mixer appearance alone does not establish slump, water reduction or strength.
- Keep later retention readings and strength results with the same batch record before drawing a product-selection conclusion.
These are AdmixChem's trial-record recommendations. The video is optional background viewing; its product-specific dosage and performance claims are not recommendations for AdmixChem grades. Use the dose-basis guide when recording supplied product and solids.
What to send for a compatibility review
Send the binder and aggregate information, PCE grade/lot, other admixtures, supplied-product dose, solids information where available, batch-water calculation, mixing order, temperatures and time-stamped observations. Include the reference mix and the result that needs improvement.