Method for testing particle packing density of concrete used powder

A technology of particle accumulation and testing method, applied in the field of particle accumulation density test, can solve the problems of inappropriate particle gradation, large accumulation volume of dry powder, disorderly arrangement, etc., and achieve the effect of simple operation.

Inactive Publication Date: 2012-08-01
CHINA STATE CONSTR READY MIXED CONCRETE CO LTD
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  • Abstract
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Problems solved by technology

[0004] Although there are many theories about close packing, how to test the particle packing density of concrete powder in actual production is a difficult problem, because it is difficult for powder particles to be arranged according to the theoretical pattern and to fill each other, but often without Regularly and randomly arranged, due to electrostatic resistance and friction between powder particles, etc., the accumulation volume of the dry powder is relatively large, and the accumulation volume of the dry powder obtained after repeated vibrations is still larger than that in the low-water gel. Compared with the volume of the slurry, it is not accurate to only use the bulk density of the dry powder to test the particle size distribution of the powder
In addition, each powder has certain characteristics, and its water demand, particle structure, auxiliary water reduction effect, etc. are different, which will have a certain impact on the fluidity of the slurry. Therefore, the fluidity of the slurry is used to test The particle gradation of the powder is also not suitable

Method used

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  • Method for testing particle packing density of concrete used powder

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] Weigh the powder with a total mass of 1200g according to the following ratio (mass ratio), mix it evenly, and prepare cement paste:

[0042] a cement : microbeads : limestone powder : silica fume = 3 : 3 : 3.5 : 0.5

[0043] b cement : microbeads : limestone powder : silica fume = 7 : 1 : 1.5 : 0.5

[0044] The water-to-cement ratio σ is 0.15, and the superplasticizer is polycarboxylate high-efficiency superplasticizer (solid content 20.2%), with a dosage of 20g; defoamer (siloxane) 0.016g; retarder (sodium gluconate ) 0.6g; the test ambient temperature is 20°C. It can be calculated that the ratio of the dry powder mass in the slurry a and b to the total mass of the slurry is:

[0045] λ=1200 / (1200+1200×0.15+20+0.016+0.6)= 0.856766.

[0046] A large number of tests have shown that when the above additives are added, the initial setting time of the slurry is greater than 18 hours.

[0047] According to the national standard GB / T 208-94, the measured density of each pow...

Embodiment 2

[0063] Following test is carried out according to the method in embodiment 1:

[0064] Weigh the powder with a total mass of 1200g according to the following ratio, mix it evenly, and prepare cement paste:

[0065] A cement : fly ash = 5 : 5

[0066] B cement : mineral powder : fly ash = 5 : 2 : 3

[0067] C cement : microbeads : silica fume = 5 : 4 : 1

[0068] D cement : microbeads : limestone powder : silica fume = 3 : 3 : 3.5 : 0.5

[0069] E cement : microbeads : limestone powder : silica fume = 7 : 1 : 1.5 : 0.5

[0070] The water-to-cement ratio σ is 0.20, the superplasticizer is polycarboxylate high-efficiency superplasticizer (20.2% solid content), and the dosage is 16g; defoamer (siloxane) 0.016g; retarder (sodium gluconate ) 0.48g; the test environment temperature is 20°C. A large number of tests have shown that when the above additives are added, the initial setting time of the slurry is greater than 18 hours.

[0071] Table 2 lists the V of components from A...

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Abstract

The invention provides a method for testing the particle packing density of concrete used powder, and the tight particle packing density degree of the concrete used powder can be tested through the ratio of the absolute volume of the mixing powder and the packing volume of powder in slurry. The method provided by the invention is simple to operate, scientific, and closer to the practical application condition, and can provide better guidance for the mix design of concrete.

Description

technical field [0001] The invention relates to the technical field of close packing of powder particles, in particular to a method for testing the packing density of powder particles for concrete. Background technique [0002] A large amount of literature shows that optimizing the particle gradation of cement and admixtures and improving the compactness of the concrete system can greatly improve the strength of concrete and the durability of various aspects. At present, there are many models and theories on close packing and particle gradation of powders. [0003] Furans believes that when the small particles just fill the gaps of the large particles, the most compact packing is formed. If there are three sizes of particles, the medium particles should just fill the gaps of the coarse particles, and the fine particles should fill the gaps of the medium and coarse particles. And thus can be extended to the situation of a variety of particles. Westman and Hugill believe tha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N9/02
Inventor 张建亮黄波王凤玲刘彬黄义雄
Owner CHINA STATE CONSTR READY MIXED CONCRETE CO LTD
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