Post Date:4,Aug,2025

Reasons for rapid slump loss:

1. Concrete admixtures and cement are not compatible, causing rapid concrete slump loss.

2. Insufficient amount of concrete admixtures, unsatisfactory slow setting and plastic preservation effects.

3. The weather is hot, and some admixtures fail at high temperatures; water evaporates quickly; bubbles overflow, causing rapid slump loss of fresh concrete.

4. The initial concrete slump is too small, and the unit water consumption is too small.

5. The construction site and the mixing station are not well coordinated, causing the tank truck to be pressed and jammed for too long, resulting in excessive concrete slump loss.

6. The measurement error of the concrete mixing weighing system is large and unstable.

7. The moisture content of coarse and fine aggregates changes.

8. Cement is stored in mixed silos and used mixedly.

9. Is the cement just hot cement in the barrel silo? If so, it is normal to lose 10CM in one hour.

10. The compatibility of admixtures with cement is very poor. Check the fluidity of the pure slurry to see how big it is. Generally, 15cm is OK, but look at the loss over time, half an hour or an hour. If the loss is too large, you need to find the admixture manufacturer to readjust their formula. Specifically, 300g of cement, 87g of water, and 1.8% of admixture are generally added or according to its recommended dosage.

11. The weather also has a great impact. In this weather, it is normal to lose 3cm in one hour!

12. There are many reasons for the rapid loss of slump, such as unqualified admixtures, unqualified cement stability, and too long transportation time. These are the reasons that affect the slump. The solution is very simple, add water and water reducer.

Solution:

1. Adjust the formula of concrete admixtures to make it compatible with cement. Before construction, be sure to do a test on the compatibility of concrete admixtures and cement.

2. Adjust the concrete mix ratio, increase or decrease the sand ratio and water consumption, and adjust the initial slump of concrete to more than 200mm.

3. Add an appropriate amount of fly ash to replace part of the cement.

4. Increase the amount of concrete admixtures appropriately, and adjust the retarding component in the admixtures (especially when the temperature is much higher than the usual temperature).

5. Prevent water from evaporating too quickly and bubbles from overflowing too quickly.

6. Use slag cement or volcanic ash cement.

7. Improve the water retention and cooling devices of concrete transport vehicles.

8. The accuracy of the measuring equipment should meet the relevant regulations, and have a valid certificate issued by the statutory measurement department, strengthen self-inspection, and ensure accurate measurement.

9. Strengthen the detection of aggregate moisture content, and adjust the mix ratio in time when it changes.

10. The cement entering the warehouse should be stored and used according to the manufacturer, variety and grade.

11. Post-addition of water reducer: that is, add water reducer after mixing sand, stone, cement and water. This method has a significant effect on inhibiting slump loss.

12. Retarder method: The theories of the effect of retarders on cement retarding include adsorption theory, complex salt formation theory, precipitation theory and control of hydroxide crystal growth theory. Most organic retarders are surface active. They produce adsorption at the solid-liquid interface and change the surface properties of solid particles, that is, hydrophilicity. Due to adsorption, the hydroxyl groups in their molecules hinder the cement hydration process on the surface of cement particles, shielding the crystals from contacting each other and changing the structure formation process.

13. Adjust concrete admixtures: Use high molecular weight water reducers and use them in combination with appropriate water-retaining components. The free water content in the concrete is increased without increasing the water consumption, which can alleviate the slump loss.