Method and device for testing initial setting time of pavement concrete

Abstract

The invention relates to a method and device for testing initial setting time of pavement concrete. The method for testing the initial setting time of the pavement concrete comprises the following steps: firstly, placing a concrete simply supported beam test piece with certain ages on a hollow plate, and arranging a temporary support for supporting the middle of a concrete simply supported beam test piece in the rectangular orifice of the hollow plate; and then removing the temporary support in the rectangular orifice; at the time, the concrete simply supported beam test piece is hung in the air; and if the concrete simply supported beam test piece is damaged, that the concrete simply supported beam test piece fails to reach initial setting is shown, and if the concrete simply supported beam test piece is not damaged, that the concrete simply supported beam test piece reaches initial setting is shown. According to the invention, a concrete entirety is taken as a researching object, mechanic concept is clear, and through researching mechanic damage under gravity, flexural-tensile stress state is reflected directly; and the method and the device have certain advantages in aspects of influences to pavement bending performance from reflecting concrete entirety early age action, improving testing stability and evaluating material design.

Description

technical field [0001] The invention relates to a method and a device for testing the initial setting time of pavement concrete. Background technique [0002] The initial setting of concrete refers to the time from adding water to the cement and beginning to lose its plasticity, that is, the time when it enters the plastic state from the flow-plastic state; the essence of the initial setting time is that the network skeleton begins to form inside the concrete, that is, the time when the concrete enters the plastic state from the flow-plastic state time. The penetration resistance meter is used to measure the initial setting of concrete. First, the mortar is sieved from the mixture with a 5mm sieve, and then the penetration resistance of the mortar penetrates into a certain depth is measured at regular intervals, and the relationship between time and penetration resistance is drawn. . Generally, the horizontal axis represents time, and the vertical axis represents penetrati...

AI Technical Summary

Problems solved by technology

[0003] However, the penetration resistance meter method sieves the mortar and removes aggregates larger than 5 mm. In fact, the strength of early-age concrete comes not only from the bonding of hydration products, but also from aggregates (new aggregates wrapped in mortar) ), or aggregates can effectively inhibit the expansion of mortar cracks, so the stress modes of mortar and concrete are different, especially when the water-cement ratio is large, the difference between concrete and sieved mortar bigger

Penetration resistance is used to measure the initial setting by using the surface hardness of the mortar to reflect the hydration degree of the mortar strength, and then reflect the network skeleton degree (strength) of the concrete, which cannot reflect the characteristics of the road concrete and the characteristics of bending and tensile stress

In addition, the penetration resistance test method is to screen the mortar from the mixture to remove aggregates larger than 5 mm. On the one hand, the test process is complicated; on the other hand, human factors in the test process also lead to large dispersion of test results.

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