What will Happen When using too much Water Reducer in Concrete

Concrete water reducing agent technology is more and more widely used in engineering construction, and it plays an important role in concrete quality control. However, excessive use of water-reducing agents will have a certain impact on concrete. Here, the phenomenon that excessive mixing of the water reducing agent in concrete is likely to occur Summarize the reasons and solutions.

Phenomenon one: Sticky tank phenomenon. Part of the cement mortar sticks to the wall of the mixer barrel, resulting in uneven concrete, less ash, and sticky concrete.

Reason: The concrete is sticky, which mostly occurs after mixing with retarder and water reducing agent, or in drum mixers with close shaft diameter ratio.

Solution: promptly clean and remove the remaining concrete; first add aggregate and part of the water to mix, then add cement, residual water, and water reducing agent to mix; use a large shaft diameter ratio or forced mixer.

Phenomenon two: false coagulation phenomenon. After exiting the machine, the concrete mixture quickly loses fluidity and even cannot be poured for construction.

Reason: Insufficient calcium sulfate and gypsum content in the cement cause the calcium aluminate to hydrate too quickly; the water reducing agent has poor adaptability to this kind of cement. When the triethanolamine content exceeds 0.05-0.1%, the initial setting will be quick but not the final setting.

Solution: Change the type of cement; adjust the admixture appropriately and make a reasonable compound; add Na2SO4 to the admixture.

Phenomenon three: Non-condensation phenomenon. After mixing with water reducing agent, the concrete has not solidified for a long time, even for a whole day and night; the surface is secreted and yellowish-brown.

Reasons: excessive mixing of water reducing agent; excessive use of retarder.

Solution: Do not exceed the recommended dosage 2-3 times, although the strength is slightly reduced, the 28d strength is reduced less, and the long-term strength is less reduced; after the final set, the curing temperature is appropriately increased, and the watering maintenance is strengthened; the formed part is removed, Re-pouring.

Phenomenon four: Low strength Phenomenon

• The strength is much lower than the result of the same age test;

  
  

• Although the concrete has set, the strength is extremely low.

  
  

Reasons: excessive mixing of air-entraining water-reducing agent causes excessive air content in the concrete; insufficient vibration after mixing with the air-entraining water-reducing agent; instead of reducing the water or increasing the water-cement ratio. The quality of the water reducing agent is not up to the requirements, such as the content of active ingredients is too low.

Solution: adopt other reinforcement measures or re-pouring; strengthen vibrating after pouring; take measures for the aforementioned reasons; appraise this batch of water reducing agent.

Phenomenon five: The slump loss is too fast. The concrete loses its workability quickly, and the slump decreases by 1-50mm every 2 to 3 minutes after being out of the tank, and there is an obvious sinking phenomenon. Large slump concrete is more prone to this phenomenon.

Reasons: the water-reducing agent has poor adaptability to the cement used, for that, you could choose KINGSUN sodium gluconate powder; the bubbles introduced into the concrete continuously overflow and the water evaporates, especially when using an air-entraining water-reducing agent; the concrete mixing temperature or the ambient temperature is high; the concrete slump is very large.

Solution: Find out the reason and take measures for the reason; adopt the post-mixing method, the water reducing agent is mixed after mixing the concrete 1-3min or even before pouring, and mixing again; be careful not to add water alone. 

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