Effect of HEMC dosage on the yield stress of cement mortar

In the test process, the factors affecting the yield stress of the mortar are: mortar stratification and effluent. The destruction of the structure by mixing, the generation of hydration products. The reduction of free water in the mortar, and the retarding effect of cellulose ether. The more commonly accepted view is that the retardation effect of cellulose ether by the adsorption effect of admixture.HEMC

The relationship between mortar g value and dosage, the change of g value reflects the change law of mortar yield stress. It can be seen that when the HEMC40 dosage is less than 0.3%. The mortar yield stress gradually decreases with the increase of the dosage. When the HEMC40 dosage is more than 0.3%, the mortar yield stress gradually increases. Mortar not mixed with cellulose ether due to bleeding and stratification.

There is not enough cement slurry between the aggregate for a lubrication role, resulting in increased yield stress and difficult to flow. Appropriate mixing of cellulose ether can effectively improve the phenomenon of mortar stratification. And the introduced bubbles are equivalent to small “beads”, which can reduce the mortar yield stress, and make it easy to flow. With the increase of cellulose ether incorporation, its fixed water content also gradually increases. When the incorporation of cellulose ether exceeds a certain value.HEMC

You can see the change of mortar yield stress over time.

When the 40 incorporation is less than 0.3%, Mortar yield stress is gradually decreasing within 0-120min. HEMC This is mainly related to the increasing severity of mortar stratification. Because the blades are a distance from the base of the instrument. After stratification, the aggregate sinks into the bottom, The upper resistance becomes smaller; At an 40 incorporation rate of 0.3%. The predominant position of hydration, The yield stress somewhat. HEMC

At an 40 incorporation of 0.5% -0.7%, The adsorption effect of cellulose ether, The rate of hydration decreases accordingly. The development trend of mortar yield stress began to change. HEMC When the 40 incorporation is greater than 0.7%, The cellulose ether is heavily adsorb on the surface of the unhydrated compounds, The low hydration rate, stress decreases over time.HEMC

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