According to our understanding, we learned that the liquid admixtures delivered to the mixing station generally involve the control of solid content. According to needs, if you want to adjust the water reduction rate, dosage, setting time and other properties, you can adjust it through changes in solid content. If you want a higher water reduction rate and a smaller dosage, you can increase the solid content appropriately; conversely, you can reduce the solid content. However, the final control of solid content is mainly based on test results. The solid content of carboxylic acid additives is generally around 7-9%.
The solid content of the admixture is directly proportional to the density. Because the density of the solid components in the admixture is greater than the density of water, the higher the solid content, the greater the density of the admixture solution.
Method for determination of solid content of admixtures
Use an analytical balance to accurately weigh about 2 grams of the original sample into a watch glass, place it in an oven at 105℃-108℃ Next, dry for three hours, take it out and weigh it, put it in the oven again, treat it under the same conditions for 30 minutes, take it out and weigh it again, repeat this twice. Compare the three data to see if constant weight is reached, and then calculate the solid content according to the following formula.
Because there are too many types of admixtures, there is no national standard for the solid content of admixtures, and there are big differences in production processes and working principles. The provisions of the national standard are within the control of the manufacturer. GB8076-2008 stipulates that when the solid content S>25%, it is controlled at 0.95S~1.05S; when the solid content S≤25%, it is controlled at 0.90S~1.10S.
How to calculate the solid content of concrete admixtures?
The appearance of admixtures is divided into water and powder. The solid content of an additive is the percentage of solid content in a liquid additive measured after a drying test. The solid content of aqueous additives is generally 20%, 40% (also known as mother liquor), and 60%. The solid content of powders is generally 98%. According to the water-reducing and enhancing capabilities of water-reducing agents, they are divided into ordinary water-reducing agents (also known as plasticizers, the water-reducing rate is not less than 8%, represented by lignin sulfonates), high-efficiency water-reducing agents (also known as super Plasticizers, water reduction rate is not less than 14%, including naphthalene series, melamine series, sulfamate series, aliphatic series, etc.) and high-performance water reducing agents (water reduction rate is not less than 25%, with polycarboxylic acid (represented by water reducing agent), and are divided into early strength type, standard type and retardant type. Powder ≥94%, liquid concentration 0-40%.
Admixture is a concrete admixture that can reduce mixing water consumption while maintaining the slump of concrete. Most of them are anionic surfactants, including lignin sulfonate, naphthalene sulfonate formaldehyde polymer, etc. After adding the concrete mixture, it has a dispersing effect on the cement particles, which can improve its workability, reduce the unit water consumption, increase the strength of the concrete and improve the durability; or reduce the unit cement consumption and save cement.
Testing the solid content of polycarboxylic acid concrete admixture
There are three methods: 1. Add water to dilute, and then use a sugar meter to visually see the solid content. 2. Use the drying method, control the temperature at about 105, and the time is 4 hours. 3. Use a hydrometer to measure its specific gravity and calculate the content, but this requires a certain amount of experience to be able to calculate it.
The high solid content of concrete admixtures means that there are relatively few ineffective ingredients added to the admixtures, and the effect of the admixtures is more obvious. A smaller amount can meet the project needs
What effect does the solid content of concrete admixtures have on concrete?
The solidification is too slow and sometimes the strength is reduced. Concrete, abbreviated as "concrete (tóng)": refers to the general name of engineering composite materials that are made of cementitious materials that bind aggregates into a whole. The term concrete usually refers to the cement concrete obtained by mixing cement as cementing material, sand and stone as aggregates, and water (which may contain admixtures and admixtures) in a certain proportion. It is also called ordinary cement concrete. Concrete, which is widely used in civil engineering.
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