We know that silica fume as a kind of admixture that can effectively increase the performance of concrete, the better its fluidity, the better the effect played, but the fluidity can not be very clear before the test, if the purchase of silica fume fluidity is not particularly good, then what to do?
Ways to improve the fluidity of silica fume
If the fluidity of silica fume is not good, then its role and effect will be greatly limited, and it will also affect the performance of the blended products, and to improve the fluidity of silica fume, there are usually two methods:
- The particles of silica fume will be processed more miniaturized, so that it is easier to disperse and flow, so as to effectively improve their own mobility, but smaller particles and more dispersion means that transportation and storage is more inconvenient.
- In order to improve the fluidity of silica fume, you can also add some appropriate auxiliary materials, such as the use of increased water, with the increase in the water content of silica fume, its fluidity naturally increased; if there is no water auxiliary, you can also use some air-entraining agent as an auxiliary material, can also effectively increase the fluidity of silica fume.
Silica fume fluidity test
The role of silica fume in concrete is very powerful, can improve the strength of concrete, human nature, durability, etc., but in practice, high-performance concrete has certain requirements for the fluidity of silica fume, in general, the better the fluidity of silica fume, the more evenly dispersed in the concrete, the better the performance of the corresponding concrete, so how can we know how the fluidity?
Undensified silica fume fluidity test
Testing the fluidity of silica fume without encryption is relatively simple, using water and dispersant and silica fume after full mixing, pour it on a glass plate to measure the flow area, in the following manner:
Take 40 grams of water, 60 grams of silica fume, 0.2 grams of dispersant (tri-poly or P530), mix thoroughly and pour it on the glass plate, let it flow naturally, when the flowing action is terminated, measure the flowing area, if the average diameter is greater than 130 mm, it can be considered as good fluidity.
In addition, I suggest that if there are conditions, you can also do the indefinite test block test, and then according to the amount of water added to determine how good the silica fume fluidity.
Densified silica fume fluidity test
The undensified silica fume is lighter and can be easily dispersed in the air, so it is more difficult and costly to transport, but after encryption, it can be easily transported, and it can also improve the labor environment and reduce labor costs, but the densified silica fume is more dense, so it is more necessary to ensure the performance of the concrete through the fluidity test.
Densified silica fume cannot be measured using simple measurements of flow area, but only using indeterminate specimens of:
Available 70% of bauxite clinker, 20% of 0-325 mesh bauxite subdivision, 3% silica fume, 7% bauxite cement, 0.2% sodium hexametaphosphate, and then add 8% to 9% of water for proportional mixing to become a cast slurry, and then dumped to the jump table or shaking table, test the slurry vibration flow value after the small amount of water and flow value, the better the fluidity of silica fume.
Silica fume liquidity test notes
- Silica fume should be completely stirred into a liquid, if the stirring time is long, but still relatively viscous, it proves that the selected silica fume samples have poor fluidity, then the subsequent test does not need to continue.
- Silica fume liquidity test, the glass plate must be placed on the horizontal table, so that the silica fume slurry to spread more evenly, conducive to the measurement work.
- The different silica fume products, its fluidity is not the same, you need to separate, average, mixed test, take more samples for measurement experiments.
