Introduction of Cement Content-reducing Admixture (III): Guidelines for the Dilution, Storage, and Incorporation of Cement Content-Reducing Admixtures in Concrete Applications
The dilution of Cement Content-Reducing Admixtures mother liquid is a crucial process that involves adjusting the concentration of the high-concentration mother liquid to a level suitable for practical application. Below are the general dilution steps and considerations:
I. Dilution Steps
1. Determine the dilution ratio:
First, based on factors such as concrete performance requirements, raw material quality, and construction conditions, determine the dilution ratio of the Cement Content-Reducing Admixtures mother liquid. This ratio is usually derived from laboratory tests and field verification.
2. Prepare dilution water: The dilution water should be clean, free of impurities and contamination to avoid affecting the performance of the Cement Content-Reducing Admixtures. Generally, tap water or purified water can be used.
3. Perform the dilution operation: Add the Cement Content-Reducing Admixtures mother liquid to the dilution water according to the determined dilution ratio, stirring thoroughly with a mixer to ensure the mother liquid is evenly dispersed in the water. The stirring time should be determined based on actual conditions, usually ranging from a few minutes to over ten minutes.
4. Test the performance of the diluted solution: After dilution, it is necessary to test whether the performance of the diluted solution meets the requirements. This can be achieved through laboratory tests or field tests, with main indicators including concrete strength, fluidity, and slump retention time.
5. Precautions： (1) Avoid vigorous stirring: During the dilution process, avoid vigorous stirring to prevent the generation of excessive foam or affecting the performance of the cement content-reducing admixture.
(2) Pay attention to the dilution ratio: The dilution ratio must be accurate; too much or too little dilution will affect the effectiveness of the cement content-reducing admixture.
(3) Storage and custody: Diluted Cement Content-Reducing Admixtures should be used promptly to avoid performance degradation from long-term storage. They should be stored in cool, dry, and ventilated places, away from direct sunlight and high temperatures.
(4) Safe use: When using cement content-reducing admixture mother liquid and diluted solutions, wear appropriate protective equipment, such as gloves and masks, to avoid skin and eye irritation or injury.
(5) Follow specifications: In the dilution and use process, follow relevant construction specifications and operating procedures to ensure safe and efficient work completion.
In summary, the dilution of cement content-reducing admixture mother liquid is a process that requires careful operation and attention to detail.
II. Storage
Only by following the correct steps and precautions can the diluted Cement Content-Reducing Admixtures maintain good performance and effectiveness. The storage time of diluted cement content-reducing admixtures is influenced by various factors, such as dilution ratio, storage conditions, ambient temperature, humidity, and the nature of the admixture itself.
Under suitable storage conditions, such as sealed, light-protected, dry, and temperature-appropriate environments, diluted cement content-reducing admixtures can be stored for a period, but the specific storage time needs to be determined based on actual situations.
Under ideal conditions, diluted cement content-reducing admixtures may be stored for several weeks to several months, but to ensure their performance and effectiveness, it is recommended to use them as soon as possible. Over time, the active components in the admixture may gradually degrade or become ineffective, affecting their use.
Furthermore, if the diluted cement content-reducing admixture exhibits sedimentation, layering, discoloration, or unusual odors during storage, it may have deteriorated or been contaminated and should not be used.
Therefore, when using diluted cement content-reducing admixtures, it is recommended to dilute according to actual needs to avoid prolonged storage affecting the use effectiveness. Attention should also be paid to storage conditions to ensure that the admixture maintains its original performance and stability during storage. If the storage time is long or the storage conditions are poor, it is recommended to conduct tests or inspections before use to ensure it meets the requirements.
III. Incorporation
The incorporation method of Cement Content-Reducing Admixtures is usually during the concrete preparation process, adding them to the concrete mixture at a certain ratio. The specific incorporation method is as follows:
1. Determine the dosage: First, based on factors such as concrete performance requirements, raw material quality, and the performance characteristics of the admixture, determine the reasonable dosage of the cement content-reducing admixture. Generally, the dosage of admixtures is calculated based on the total amount of cementitious materials in the concrete, usually a percentage value, such as 0.06% to 0.6% of the total cementitious materials.
2. Dissolve or disperse: For liquid admixtures, it may be necessary to first dissolve or disperse them in a suitable amount of water to ensure uniform distribution in the concrete. For powdered inorganic admixtures, it may be necessary to first mix them with water to make a slurry.
3. Add to concrete mixture: During the concrete mixing process, add the dissolved or dispersed admixture (or admixture slurry) to the concrete mixture according to the determined dosage. Continue to mix the concrete to ensure the admixture is evenly mixed with the concrete mixture.
4. Adjust the mix ratio: Since the addition of admixtures may change the workability and strength characteristics of concrete, it is necessary to adjust the concrete mix ratio according to actual conditions. For example, it may be necessary to reduce the amount of cement in the concrete and correspondingly increase the amount of aggregate, such as stone, to maintain the weight and performance of the concrete unchanged.
5. Thorough mixing: After adding the admixture, continue to mix the concrete for a period (usually a few minutes to over ten minutes) to ensure the admixture is fully and evenly mixed with the concrete mixture.
6. Subsequent treatment: Concrete with added admixtures needs to be processed according to normal construction techniques, such as pouring, vibration, and curing. During the curing process, attention should be paid to maintaining suitable humidity and temperature of the concrete to ensure its strength and durability are fully developed.
It should be noted that different brands and types of admixtures may have different incorporation methods and requirements. Therefore, when using admixtures, carefully read the product instructions or consult with factory technical personnel to ensure the correct incorporation method is followed to achieve the desired effect.
IV. Precautions
1. Raw Material Aspects
(1) Compatibility：
Ensure compatibility between the admixture and cement, admixtures (such as fly ash, slag powder, etc.). Different manufacturers' cement or admixtures may have different effects on the performance of the admixture. For example, some mineral components in cement may undergo chemical reactions with the admixture, affecting the setting time or strength development of concrete, so compatibility tests are recommended before use.
(2) Quality Stability：
The quality of the admixture should be stable. If the composition or performance of the admixture fluctuates greatly, it may lead to unstable concrete performance. When purchasing, choose reliable quality and mature production process products, and conduct regular inspections as required.
2. Mix Design
(1) Accurate Measurement： The dosage of the admixture must be accurately measured. Too much can lead to excessive retardation, insufficient strength, and other issues in concrete; too little will not achieve the expected cement content-reducing effect. Generally, precise measuring equipment, such as electronic scales, should be used to ensure the dosage error of the admixture is within the specified range.
(2) Adjust Mix Ratio：
When using admixtures, adjust the concrete mix ratio appropriately based on their performance. For example, since admixtures may improve the workability of concrete, the water-cement ratio may need to be reduced accordingly to ensure strength.
3. Mixing and Construction
(1) Uniform Mixing： The admixture should be thoroughly mixed during the concrete mixing process. Inadequate mixing can lead to significant performance differences in local areas of the concrete. Mixing time should be extended according to the type and capacity of the mixer to ensure even distribution of the admixture in the concrete.
(2) Construction Conditions： Pay attention to environmental temperature and humidity during construction. Low temperatures can affect the effectiveness of the admixture, such as delaying the setting time of concrete. Insulation measures or adjustments to the dosage of the admixture may be necessary when constructing in low-temperature environments. Humidity can also affect the drying shrinkage and other properties of concrete, which should be considered comprehensively when using admixtures.
