Calcium lignosulfonate uses in concrete
Calcium lignosulfonate in concrete action and dosage – Stone Refractories
I. Calcium lignosulfonate water reduction in concrete reinforced role
Calcium lignosulfonate and sodium lignosulfonate reducing agent is a surface-active agent, added to the concrete, due to the orientation of hydrophobic groups adsorbed on the surface of cement particles, so that the cement with a negative charge. Cement particles have the same charge in the charge repulsion exclusion from each other under the action of dispersion of cement in water the initially-formed into a dispersion structure floc structure, flocculation cohesion body of free water is released, so as to achieve the purpose of reducing agent. Observations show that lignin added to the concrete after mixing for 5 minutes more than 80% of the reducing agent is adsorbed, clearly visible under the electron microscope, the center point of significantly increased hydration, hydration evenly distributed, hydrated crystal fibers longer various microscopic characteristics.
Thus, the adding of calcium lignosulfonate, leaving the pores free water evaporation is small, dense internal structure, that is, reduction of the porosity is clearly beneficial to increase the strength of concrete, cement improves the size and distribution of the pore structure conditions, the crystal growth rate slow, crystal growth more fully, and thus get more fibrous crystals interspersed with each other to form a strong network structure, so that the concrete strength significantly increased.
Therefore, in concrete mixed with lignin superplasticizer, concrete mixture can reduce water consumption and reduce water-cement ratio, improved workability, is conducive to pumping, improve concrete strength, density and durability.
Second, the lignin water reducer in concrete dosage and key performance indicators
1. to improve concrete performance: When the same amount of cement, concrete slump similar to the blank can reduce water consumption by 10-15%, 10-20% increase in 28-day strength, a strength of about 10%.
2. saving cement consumption: When the concrete strength and slump similar, can save about 10% of cement, use one ton of cement water reducing agent can save 30-40 tons.
3. to improve the workability of concrete: When the amount of cement concrete and water consumption constant, low plasticity of concrete slump can be increased about twice (by a 3-5cm up to 8-18cm), early strength and undoped who was close.
4. the bleeding rate decreased: in concrete slump basically the same case, the doped lignin bleeding rate than those who are not doping can be reduced more than 30%, while maintaining the same water-cement ratio, increasing slump situation , it is also due to the introduction of air lignin hydrophilic and other reasons, the bleeding rate.
5. shrinkage performance: initial (1-7) days compared with non-water-reducing admixture, was close to or slightly decreased, 28 days and late (except saving cement above), a slight increase, but the increase values did not exceed 0.01% (0.01mm / m).
6.to improve the density of concrete, improve concrete impermeability. By the B = 6 grade up to B = 12-30 level.
7. no chlorine salt, no corrosion of steel hazards.