Water Reducing Agent: Optimizing the Rheology and Workability of Shotcrete

What is a Concrete Water-Reducing Agent?

Superplasticizer is a vital element of concrete blends. It boosts the consistency of concrete, creating it simpler to mix and place, thus increasing the flexibility of concrete for the construction industry.
The quantity of water-reducing substance is affected by factors such as particle size and compressive strength, among others, in relation to the performance of concrete, and its application is also impacted by the environmental conditions and construction requirements. Proper usage of water-reducing agents can improve the consistency of concrete, minimize concrete breaking, and boost the strength of concrete. The purpose of water-reducing agents also includes decreasing the water content of concrete, enhancing the strength of concrete, and enhancing the overall quality of concrete. Additionally, water-reducing agents can reduce dust formation, reduce concrete shrinkage, enhance concrete resilience, improve the appearance of concrete, and improve concrete’s capability to corrosion.

What are the features of concrete water-reducing agent?
The concrete water-reducing agent is an additive that minimizes the water usage of concrete while keeping its flow essentially unchanged, hence enhancing the sturdiness and longevity of concrete, or raising the fluidity of concrete and enhancing the workability of concrete within the same cement dosage and water-cement ratio.

1. Greasing effect.

The polar hydrophilic groups in the water-reducing agent orient themselves to adsorb onto the surface of cement particles and readily bond to water molecules through hydrogen bonds. The strength of this hydrogen bonding is considerably greater than the molecular attraction between water molecules and cement particles. When adequate water-reducing agent is absorbed by the cement particles, with the assistance of R-SO3θ and the hydrogen bonding in water molecules, along with the hydrogen bonding between water molecules, a stable solvated water film creates on the surface of cement particles. This film functions as a three-dimensional protective barrier, preventing direct contact between cement particles and operating as a lubricant between particles.

2. Moistening effect.

After cement and water are mixed, the surface of the particles is moistened by water, and the parameters of wetting have a significant impact on the performance of fresh commercial concrete. The lowering in surface free energy resulted by natural moistening can be determined using the formula advised by Glbbs.

3. Water-reducing effect.

After the addition of high-efficiency water-reducing agents in commercial concrete, the water-cement ratio can be substantially lowered while preserving fluidity. High-efficiency water-reducing agents have a water reduction rate of up to 10% to 25%, while regular water-reducing agents have a water reduction rate of 5% to 15%, thus the name high-efficiency water-reducing agent. The water reduction effect is largely due to the adsorption and diffusion of water-reducing agents in commercial concrete.

4. Plasticizing result.

After adding a water-reducing representative to concrete, it can raise the workability while retaining the water-cement ratio unchanged. Common water-reducing agents, in the case of keeping the precise similar quantity of cement, can create the brand-new industrial concrete depression rise by over 10cm; high-performance water-reducing agents can create a slump of 25cm of industrial concrete.

Concrete water-reducing agent process of action introduced

1. Distributing influence:
After the concrete is mixed with water, as a result of the hydration of cement particles, the surface of cement particles develops a dual electrical layer structure, leading to the formation of a solvent water film and anisotropic charged areas between cement particles creating a bridging effect. This ensures that 10% to 30% of the mix water is covered by the concrete particles and cannot participate in free flow and lubrication, consequently influencing the flow of the concrete mix. Whenever the water-reducing additive is added, the water-reducing additive molecules can position themselves and adsorb on the surface of cement particles, creating a similarly charged surface (typically negative) on the cement particles. This triggers electrostatic repulsion, urging the cement particles to disperse from each other, breaking down the bridging structure, and releasing the enclosed water. As a result, the water can flow more effectively, thus improving the workability of the concrete mix.

2. Lubrication effect:
The hydrophilic group in the water-reducing substance is highly polar, permitting the adsorption film of the water-reducing substance on the surface of cement particles to create a stable layer of solventized water film through with water molecules. This water film offers effective lubrication, significantly lowering the friction between cement particles and further enhancing the workability of concrete.

3. Spatial site-resistance effect:
The water-reducing substance structure with hydrophilic branched chains extends in a liquid mixture, developing a compact hydrophilic three-dimensional adsorption film on the surface of adsorbed cement particles. When the concrete particles are adjacent to each other, the adsorption layers commence to intersect. This results in spatial site-resistance between cement particles, enhancing the repulsion of spatial site-resistance and increasing the bonding hindrance between cement particles, thus maintaining the desired slump of the concrete.

4. Slow-release impact of graft copolymerization branched chains:
New water-reducing agents, such as polycarboxylic acid water-reducing agents, have branching chains grafted onto the molecules of the water-reducing additive. These branched chains provide both spatial site-resistance impacts and, in the highly alkaline environment of cement hydration, can be slowly emitted, leading to the emission of polycarboxylic acid with scattering effect. This enhances the scattering result of cement particles and manages slump loss.

The volume of water-reducing representative is impacted by the particulate dimension as well as compressive endurance, etc., on the performance of concrete, and additionally its quantity is similarly affected by weather problems and construction demands. The appropriate use of water-reducing agents can enhance the uniformity of concrete, reduce the cracking of the concrete, izajoo similarly increase the strength of concrete. The role of water-reducing agents additionally consists of lowering the water content of concrete, which boosts the strength of concrete and makes the general performance of concrete premium. Furthermore, water-reducing agents can also lower the creation of dirt, decrease the reducing of concrete, increase the sturdiness of concrete, boost the look of concrete, and boost the corrosion resistance of concrete.

Concrete Water-Reducing Agent

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