What Is Plasticizer In Civil?
Plasticizer us in concrete for workability, Strength, and Durability of concrete. Plasticizer in concrete for Water-reducing admixtures usually reduces the required water content for a concrete mixture by about 5 to 12 percent. The use of water-reducing admixtures is defining as Type A in ASTM C 494. The WRA mainly affects the fresh properties of concrete.
Which is measured by the dilution indicated in ASTM C 143-90. Water-reducing admixtures that delay the initial setting time by more than three hours. It is classified as a water-reducing admixture with a debugging effect (Type D).
Commonly used water-reducing admixtures (WRA) are lignosulfonates and hydrocarboxylic acids. The use of hydro carboxylic (HC) acids as WRA requires higher water content (w/c) compared to the lignosulfonates. Rapid bleeding is a problem for concrete treated with hydro carboxylic (HC) acids.
The increase in a slump is different according to its types and dosage. The typical dosage rate is based upon the cementitious material content (millilitres per hundred kilograms). The figure below illustrates the influence of the dosage of Lignosulfonates and HC acid on a slump.
It is shown in the figure that Hydro Carboxylic (HC) acids give a higher slump compared to lignosulfonates with the same dosage. Water-Reducing Admixtures (WRA) has been used primarily in hot weather concrete pumping, placing, and tremie.
Careful concrete placement is required, as an initial setting time of cement will take place an hour earlier. It is also shown that the use of Water-Reducing Admixtures (WRA) will give a higher initial concrete compressive strength by 10% compared to the control mixture.
Another benefit of using Water-Reducing Admixtures (WRA) is that higher concrete density is achieved, which makes the concrete less permeable and has higher durability.
What Is Superplasticizer In Civil?
This Superplasticizers, also known as high range water reducers, same as a plasticizer, are chemical admixtures used where well-dispersed particle suspension is required. Polymers are used as dispersants to avoid particle segregation also to improve the flow characteristics of suspensions such as in concrete applications.
Their addition to mortar or concrete allows a reduction of the water to cement ratio (W/C), not affecting the workability of the mixture, and enables the production of high-performance concrete and self-consolidating concrete. This effect drastically improves the performance of the fresh, hardening paste. Strength of concrete increases when water to cement (W/C) ratio decreases.
Their working mechanisms lack a full understanding, revealing, into certain cases, cement-superplasticizer incompatibilities. The addition of superplasticizer in during transit is a fairly new development within the industry. Superplasticizer added in transit through automated slump management systems, such as Verify, allows concrete producers to maintain slump until without reducing concrete quality.
Difference Between Plasticizer And Superplasticizer in Civil
| Sr.No. | Plasticizer | Superplasticizer |
| 1 | To achieve a higher strength by decreasing the water-cement ratio at the same workability as an admixture free mix. | Superplasticizer by Self-leveling, Self-compacting concrete and also Penetration and compaction round dense reinforcement |
| 2 | To achieve the same workability by decreasing the cement content so as to reduce the heat of hydration in mass concrete. | Improved durability by removing water to reduce permeability and diffusion. |
| 3 | To increase the workability so as to ease placing inaccessible locations | Reduced shrinkage, especially if combined with reduced cement content. |
| 4 | Water reduction of more than 5% but less than 12% | Water reduction of more than 6% but less than 25% |
| 5 | This Plasticizer called water reducer | This Superplasticizer called high range water reducer |
| 6 | It is an additive used to improve the plasticity of a certain substance | It is a water-reducing admixture capable of producing large water reduction or great flammability |
| 7 | This increases the plasticity matricidal such as water reducer in a concrete mixture | This further increases the water requirement for concrete mixture increase the strength and durability of concrete |
| 8 | Add plasticizer 0.1 – 0.5 % weight of cement | Add Superplasticizer 0.5 – 3% weight of cement |
FAQ: Plasticizers and Superplasticizers in Concrete
What is a plasticizer in concrete?
A plasticizer is a type of water-reducing admixture used in concrete to improve workability, strength, and durability. It reduces the water content required for a given mix, typically by 5 to 12 percent, without compromising the mix’s workability.
How do plasticizers affect the properties of concrete?
Plasticizers improve the flowability and workability of concrete, making it easier to place and finish. They also enhance the concrete’s density, leading to increased strength and durability. By reducing water content, they help in achieving higher compressive strength and reduced permeability.
What is the difference between plasticizers and superplasticizers?
Plasticizers are used to improve the workability of concrete while reducing water content by 5 to 12 percent. Superplasticizers, also known as high-range water reducers, can reduce water content by more than 6 to 25 percent and are used to produce high-performance and self-consolidating concrete with very low water-to-cement ratios.
What are superplasticizers used for in concrete?
Superplasticizers are used to significantly enhance the flow and workability of concrete while maintaining a low water-to-cement ratio. They are ideal for producing high-performance concrete, self-compacting concrete, and concrete with dense reinforcement. They also help in reducing water permeability and improving durability.
How does the dosage of plasticizers and superplasticizers impact concrete?
The dosage affects the slump and workability of concrete. Plasticizers typically have a dosage rate of 0.1 – 0.5% of the weight of cement, while superplasticizers are used at 0.5 – 3%. Superplasticizers often result in higher slumps and improved flow compared to plasticizers.
What are the common types of plasticizers and superplasticizers?
Common plasticizers include lignosulfonates and hydroxycarboxylic acids. Superplasticizers often include sulfonated melamine formaldehyde and polycarboxylate ethers. Each type has specific properties and effects on concrete performance.
Can superplasticizers be added during transit?
Yes, superplasticizers can be added during transit using automated systems. This helps maintain the desired slump and workability of the concrete without compromising its quality.
What are the potential issues with using superplasticizers?
One potential issue is cement-superplasticizer incompatibility, which can affect the performance of the concrete. Additionally, superplasticizers may cause increased bleeding in some mixtures, particularly when used with certain types of cement.
How do plasticizers and superplasticizers impact the heat of hydration in mass concrete?
Plasticizers can reduce the cement content to lower the heat of hydration, while superplasticizers allow for a reduced water-to-cement ratio without compromising workability, which can help manage heat generation in large concrete pours.
Are there any specific applications for plasticizers and superplasticizers?
Plasticizers are commonly used in general concrete applications where improved workability is needed. Superplasticizers are used in high-performance concrete applications, including those requiring self-compacting properties or where very low water-to-cement ratios are desired.
