Concrete slump loss over time control methods include: retardation control method, modified control method, particle isolation method and other methods.
Retardation control method: This method uses additives to control slump loss. The admixture added to the concrete is mainly the retarder components such as sugar, gluconic acid, hydroxycarboxylic acid, phosphoric acid, lignin sulfonate, zinc salt, hydroxycarboxylate, borate and fluosilicate. Due to their different structures, these components with retarding properties are suitable for different kinds of concrete. Retarder components are added to match the composition of concrete. Adding after three minutes in the stirred concrete the appropriate retarder, can effectively control the slump loss over time.
Modification control method: The main purpose is to modify the water-reducing agent in the pumping agent, water-reducing agent is an important component in the pumping agent. Pumping agent is an compound of superplasticizer, air-entraining agent, retarder and drag reducing agent. Modified methods are divided into physical modification methods and chemical modification methods. Modification should pay attention to: different pumping agent contained the water reducer ratio and efficacy is different, so need to choose a suitable pumping agent, add the appropriate amount of pumping agent, and pay close attention to its retarding situation.
Isolation Particle Method: The role of the water-reducing agent is to disperse the cement particles quickly so as to increase the fluidity of the concrete and reduce the amount of water added. However, with the passage of time, dispersed cement particles tend to aggregate. In this case, an appropriate amount of air-entraining agent can be added, and the air-entraining agent generates micro-bubbles. The micro-bubbles not only separate the cement particles, but also Can play the role of lubrication, can effectively control the concrete slump loss over time.
Other methods: In addition to the above control methods, there are many ways to control the slump loss over time as long as the above causes of slump loss can be controlled. For example, in low temperature, humid environment for concrete mixing transport; use of low basicity of cement as raw materials.