Evaluation method of air-entraining effect of air-entraining agent for cement concrete
A cement concrete and evaluation method technology, applied in the direction of surface tension analysis, etc., can solve the problems of reduced effect of air-entraining agent, loss of objectivity, insufficient evidence, etc., and achieve the effect of less influencing factors, operability and comparability
Inactive Publication Date: 2016-06-01
RES INST OF HIGHWAY MINIST OF TRANSPORT
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Problems solved by technology
However, the cement concrete air content method has a great relationship with the ambient air pressure. Under the same mix ratio, the effect of the air-entraining agent in the low-pressure environment is reduced, and it loses objectivity as a method for evaluating air-entraining agents.
In the air content of cement mortar (density method), because there are many factors that affect the density of mortar, it is insufficient to judge the air content from the density and then judge the effect of air-entraining agent.
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[0037] Select four representative air-entraining agents: (A) high-efficiency air-entraining agent (Hb-1German), (B) triterpene saponins (SJ-1), (C) rosin thermopolymers (ED-2) and (D) alkylsulfonate (SI-1). Prepare saturated calcium hydroxide saturated solutions with an initial concentration of about 4% of the air-entraining agent respectively, and measure the surface tension; then reduce the concentration to half, measure the surface tension, and repeat until the surface tension of the saturated solution is close to that of calcium hydroxide (please add hydroxide The specific value of the surface tension of a saturated solution of calcium, and the instrument used to measure the surface tension). The surface tension of a saturated solution of calcium hydroxide is 75 mN m -1 , the measuring instrument is a fully automatic surface tensiometer, model JYW-200.
[0038] Measurement result is as shown in table 1, draws the curve of saturated lye concentration-surface tension (as ...
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Abstract
The invention discloses a method for evaluating the air entraining effect of an air entraining agent for cement concrete. The method for evaluating the air entraining effect of the air entraining agent for cement concrete is characterized by comprising the following steps: measuring the variation data of surface tension of an air entraining agent A and an air entraining agent B along with the concentration variation of the air entraining agents in a saturated calcium hydroxide solution respectively; according to the measured data, respectively finding out the concentration M and the concentration N of the air entraining agent A and the air entraining agent B in the saturated calcium hydroxide solution when the surface tension generates an inflection point; enabling K to be equal to M / N, if K is greater than 1, the air entraining effect of the air entraining agent B is better than that of the air entraining agent A, otherwise, the air entraining effect of the air entraining agent A is better than that of the air entraining agent B, and under the regular matching, the doped amount of the air entraining agent A required for reaching the same concrete gas content is K times that of the air entraining agent B.
Description
technical field [0001] The invention relates to an evaluation method for the air-entraining effect of an air-entraining agent used in cement concrete, and belongs to the field of material testing methods. Background technique [0002] Under normal circumstances, ordinary water will not foam. Even under the action of violent stirring or vibration, air will be involved in the water to form small bubbles. After standing still, the bubbles will float up and burst quickly. However, when the air-entraining agent is added to the water, a large number of air bubbles are introduced after shaking or stirring. The reason is that the surface of the liquid tends to shrink automatically, and foaming is a process in which the area of the interface increases greatly. In the case of constant surface tension, the free energy of the system will inevitably increase greatly, which is a thermodynamically unstable system. This causes the bubbles to shrink and collapse. In the presence of an ai...
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IPC IPC(8): G01N13/02
Inventor 柯国炬田波王稷良刘英何哲
Owner RES INST OF HIGHWAY MINIST OF TRANSPORT