Method and device for measuring initial and final set time for non-damage type concrete

Abstract

The related damageless detection device for initial and final setting time of concrete comprises: a transmission bar, two baffle plates, a dial gage, and a clamp screw. Wherein, one end of the bar crosses a baffle plate to be fixed by the screw, another end crosses another plate to contact with the gage. This invention is smart and convenient, and special fit to on-scene detection.

Description

technical field [0001] The invention relates to a method for testing the initial and final setting time of concrete and the technical field of a multifunctional testing device for the initial and final setting time, plastic shrinkage rate and long-term drying shrinkage of concrete designed accordingly. Background technique [0002] With the progress of modern concrete technology, more and more rely on various admixtures to improve the performance of concrete, and the initial and final setting time of concrete is often the demarcation point of various properties of materials, the time-sharing admixture of admixtures and construction All requirements require accurate measurement of the initial and final setting times of concrete. Especially in the multi-level pouring construction of roller compacted concrete pavement, whether the initial setting time of concrete is accurately measured directly determines the quality of the overall construction. At present, the methods for mea...

AI Technical Summary

Problems solved by technology

The penetration resistance method mainly calculates the initial and final setting time by testing the early mechanical properties of concrete. This method has the following defects: 1. The stones in the concrete are removed during the test, and the initial and final setting time of the mortar corresponding to the concrete is actually tested. Final setting time, because the influence of stones on the setting time of concrete cannot be predicted, the essence of the whole standard test is the initial and final setting time of mortar rather than the exact initial and final setting time of concrete

2. Since it is necessary to continuously monitor the mechanical properties of the concrete material during the setting process, it is necessary to artificially carry out a pressure test on the material. In order to obtain a continuous experimental curve, this will inevitably cause multiple damage points and change the structure of the mortar body. The penetration force obtained in the later measurement is inaccurate. Third, the penetration pressure is artificially loaded, which is greatly affected by the experimenter, and the operator's operating proficiency also has a relatively large impact on the test structure, so human error has a huge impact on the experimental results

4. The entire test process lasts for a long time, and cannot be automatically recorded, and the experimental workload is heavy

However, there is no standard for the plastic free shrinkage of concrete at present, and there is no suitable device to measure it.

The test method for long-term shrinkage of concrete stipulated in the current standard has the following defects: 1. The original test position of the specimen cannot be guaranteed during each test, the data is discrete, and the repeatability of the experiment is poor

2. Due to the differences in thermal expansion and wet expansion performance between the materials used in the test equipment and the concrete materials, system errors often result

3. The workload of the test process is heavy, and it cannot be tested online for a long time

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