Potentiometric titration determination method of cemented sand gravel cement content

Abstract

The invention discloses a potentiometric titration determination method of cemented sand gravel cement content, which comprises the following steps: (1) preparing at least three standard cemented sand gravel / cement mixtures with equal mass and different cement contents; (2) adding water into the standard cemented sand gravel / cement mixtures and diluting to obtain standard mortar mixed liquor; (3) adding a phenolphthalein indicator into clear liquid of the standard mortar mixed liquor, then titrating by using NH4CI aqueous solution till the clear liquid is colorless, recoding the titration quantity of the NH4CI aqueous solution and further obtaining a standard curve between the titration quantity of the NH4CI aqueous solution and the content of cement in the standard cemented sand gravel / cement mixtures; (4) taking the cemented sand gravel / cement mixtures to be detected, adding water and diluting to obtain mortar mixed liquor; and (5) adding the phenolphthalein indicator into clear liquid of the mortar mixed liquor, then titrating by using NH4CI aqueous solution till the clear liquid is colorless to obtain according to the standard curve. The potentiometric titration determination method has the advantages of simplicity in operation, easiness in implementation and short time consumption and is suitable for quickly determining the content of newly-mixed cemented sand gravel cement on site and controlling the construction quality of cemented sand gravel.

Description

technical field [0001] The invention relates to a phenolphthalein titration method for determining the cement content of gelled sand and gravel. Background technique [0002] Concrete sand and gravel is a new type of dam-building material whose performance is between that of concrete and soil. It is made by simply mixing riverbed sand and gravel and excavation waste as aggregate, adding water and a small amount of cement and other cementitious materials. The cemented sand and gravel dam has less cement consumption, lower heat of hydration temperature rise, and lower aggregate requirements. The construction process is simple and the cost can be greatly reduced. However, due to the low cement content of cemented sand and gravel materials and the simple mixing method, the uniformity of cement distribution after on-site mixing cannot be guaranteed. The cement content of the newly mixed cemented sand and gravel is measured to control the construction quality. [0003] For ordin...

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Problems solved by technology

However, none of these methods can meet the requirements of rapid on-site detection of cement content in cemented sand and gravel.

For example, the method of spraying phenolphthalein is to spray phenolphthalein on the freshly mixed cemented sand and gravel, and judge the mixing condition of the cemented sand and gravel by the discoloration of phenolphthalein. It can only be seen qualitatively where the cement is contained, and the cement content cannot be well identified.

Another example is the EDTA titration method. The basic principle is to use ethylenediaminetetraacetic acid sodium salt to titrate the solution containing calcium ions, and to obtain the content of cement by titrating the calcium ion content. It is a method with high precision, but the test The steps are too cumbersome, there are many influencing factors, and the necessary NaOH solution in the test is a strong alkali, which is inconvenient for field tests

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