Many important characteristics of concrete are influenced by the ratio of water to cementitious materials used in the mixture. By reducing the amount of water, the cement paste will have higher density, which results in higher paste quality. An increase in paste quality will yield higher compressive and flexural strength, lower permeability, increase resistance to weathering, improve the bond of concrete and reinforcement, reduce the volume change from drying and wetting, and reduce shrinkage cracking tendencies.
Superplasticizers Superplasticizer, also known as high range water reducers, are chemical admixtures used where well-dispersed particle suspension is required. These polymers are used as dispersants to avoid particle segregation (gravel, coarse and fine sands), and to improve the flow characteristics (rheology) of suspensions such as in concrete applications. Their addition to concrete or mortar allows the reduction of the water to cement ratio, not affecting the workability of the mixture, and enables the production of self-consolidating concrete and high performance concrete.
This effect drastically improves the performance of the hardening fresh paste. The strength of concrete increases when the water to cement ratio decreases. However, their working mechanisms lack a full understanding, revealing in certain cases cement-superplasticizer incompatibilities.
Another benefit of superplasticizers is concrete early strength enhancement (50 to 75%). The initial setting time may be accelerated up to an hour earlier or retarded to be an hour later according to its chemical reaction. Retardation is sometimes associated with range of cement particle between 4 – 30 mm. The use of superplasticizers does not significantly affect surface tension of water and does not entrain a significant amount of air. The main disadvantage of superplasticizer usage is loss of workability as a result of rapid slump loss and incompatibility of cement and superplasticizers.
Sodium Naphthalene Sulfonate Formaldehyde (SNF) SNF is a light yellow to yellowish brown powder, which is an anionic surfactant. It is widely used for the preparation of free-flowing and pumpable concrete mixture in the construction industry. SNF can be used as raw material for compound accelerators, anti-freezing agents, and retarders, in different construction industries. Its high purity feature makes cement particles with high low foaming, high range water reducing and strengthening. In addition, it also improves cement mobility and workability.
SNF is easily soluble in ethylene glycol, diethylene glycol, glycerol, and water, slightly soluble in alcohols, but it is insoluble in organic solvents. Furthermore, it is highly utilized in various industries such as agriculture, plastics & rubber, paper, construction, textile, oil, and others.
Applications
SNF is highly effective water reducing agent for promoting accelerated early and ultimate strength development in concrete and mortar, commonly referred to as a superplasticizer, also named Naphthalene Sulfonate Formaldehyde Condensate (NSF), PNS and FDN etc.
SNF has a good adaptability to various cements and it is no erodent to reinforcing bar and nonpoisonous and pollution-free.
SNF has been applied to the highway, bridge, tunnel, water conservancy hydroelectric project, port, quay, skyscraper, power engineering, industrial and civil building, prestressing force component and high range concrete etc.
