Cement-based material alkali aggregate reaction measuring device and measuring method

Abstract

The invention provides a cement-based material alkali aggregate reaction measuring device and a measuring method. The device comprises a constant-temperature box, a temperature control device used for adjusting the temperature of liquid is arranged in the box body, and a limiting groove is engraved in a bottom plate on the lower portion of the box body; a limiting plate parallel to the bottom plate is arranged at the upper half part of the hollow cavity, and a first limiting hole is formed in the limiting plate in a penetrating manner; a heat preservation cover plate is arranged on the top of the box body and is parallel to the bottom plate, a second limiting hole is formed in the heat preservation cover plate in a penetrating mode, and a displacement meter is arranged over the first limiting hole; and the device further comprises an upper measuring nail and a lower measuring nail which are fixed to the two ends of a mortar rod. When the device works, displacement data of the upper measuring nail is measured through the displacement meter, so that the length change value of the mortar rod is obtained, and the expansion rate of the mortar rod is obtained based on the length change value. The device is simple in design and convenient to operate, the method is clear, and the change of the expansion rate of the cement mortar test piece under the alkali aggregate reaction condition can be monitored in real time.

Description

technical field [0001] The invention relates to the technical field of civil engineering, in particular to a measuring device and method for alkali-aggregate reaction of cement-based materials. Background technique [0002] Alkali-aggregate reaction means that after the active aggregate in the cement-based material reacts with alkaline substances, an alkali calcium silicate gel is formed inside the specimen, and the alkali calcium silicate gel expands after absorbing water, thereby causing the specimen to expand. Generally, the alkali-aggregate reaction is evaluated by the expansion rate of the specimen. The alkali in cement and other cementitious materials reacts with the active silica in the aggregate to form alkali silicic acid gel, which absorbs water and expands, and the hardened cement stone around the aggregate restrains the expansion. When the tensile stress exceeds its tensile strength, concrete cracks. Therefore, the effect of clear alkali aggregate reaction on c...

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Problems solved by technology

Existing specifications such as "Hydraulic Concrete Test Regulations" (SL352-2006) and "Hydraulic Concrete Sand and Gravel Aggregate Test Regulations" (DLT5151-2014) etc. evaluate the alkali aggregate reaction on the expansion rate of cement mortar specimens. This method is intuitive, simple and has a wide range of applications, but it cannot continuously measure the length change of mortar specimens

Another test method for the alkali-aggregate reaction of cement-based materials uses the mortar rod rapid test method. In the test, the mortar rod is soaked in NaOH solution at 80 °C. A large error is caused under the influence of the influence, and the length change in this process cannot be quantified, thus affecting the accuracy of the alkali-aggregate reaction of the cement mortar specimen

In addition, if the number of measurements is too frequent, the loss of NaOH solution will be aggravated

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