Cement stabilization broken gravel matching ratio design method based on vibration tests

Abstract

The invention discloses a cement stabilization broken gravel matching ratio design method based on vibration tests. The cement stabilization broken gravel matching ratio design method includes the following steps that firstly, dense skeleton type grading is determined; secondly, cement is added into broken gravel, and a cement stabilization broken gravel mixed material is prepared, and the maximum dry density and the best water content of the mixed material are determined; thirdly, a test piece of the cement stabilization broken gravel mixed material is manufactured; fourthly, the test piece is cured by 6 d in a standard environment and is immersed in water by 1 d; fifthly, the 7 d unconfined compressive strength and the 7 d splitting strength of the test after curing are tested, and the 7 d unconfined compressive strength representative value and the 7 d splitting strength representative value are calculated; sixthly, the designed adding amount Copt of the cement is determined; and if the Copt meets the requirement, design can be completed. By means of the cement stabilization broken gravel mixed material designed through the method, a dense framework structure can be well formed and is not likely to be separated, the cement is saved by 20% to 40%, the strength is improved by about 30%, and social and economic benefits are obvious.

Description

technical field [0001] The invention relates to the technical field of road engineering, in particular to a method for designing the mixing ratio of cement-stabilized broken gravel based on a vibration test. Background technique [0002] Broken gravel or gravel is the main material for building road pavement base. Compared with crushed gravel, crushed gravel has fewer crushing surfaces, smooth surface, and poor angularity, resulting in relatively low strength of cement-stabilized crushed gravel and easy segregation. In order to increase the strength of cement to stabilize broken gravel and reduce segregation, increasing cement dosage and adopting finer gradation have become the most common technical means in engineering practice. It is almost a consensus that the cement dosage should reach more than 5-6%. As a result, the cement-stabilized broken gravel base has serious shrinkage cracks, and other damages such as pumping and network cracking have greatly shortened the servi...

AI Technical Summary

Problems solved by technology

In Table 1, the content of aggregates above 19mm is too low to ensure that the coarse aggregates are fully contacted to form a skeleton structure; the content of aggregates below 4.75mm is too low to fully fill the gaps of coarse aggregates to achieve Dense state; the content of powder below 0.075mm is too low, it is difficult to ensure that the mixture has sufficient cohesive force in the construction state, and it is easy to cause construction segregation

[0014] (2) The traditional heavy-duty compaction method is proposed based on 12-15 tons of static rollers, which is seriously inconsistent with the modern heavy-duty vibratory rollers of more than 20 tons

[0015] (3) The static pressure forming method of the test piece cannot simulate the actual rolling construction conditions on site well, so that the internal structure of the indoor formed test piece does not match the internal structure of the on-site rolling, that is, the test piece does not have authenticity, reliability and Representativeness, resulting in large discrepancies between indoor performance test results and the actual application effect of the grassroots, used to guide material design and site construction and pavement design will inevitably mislead engineering and technical personnel

However, there are still many deficiencies in the current vibration method for designing cement-stabilized crushed gravel: (1) There are various types of vibration testers, and their parameter settings are not the same.

The existing specifications only make relevant provisions on the working frequency, exciting force and static surface pressure, but do not make provisions on the amplitude, working weight, and the weight of the boarding and disembarking systems, resulting in the inability to accurately describe the tester that meets the requirements of the code. It is also difficult to ensure that the working status of the vibrating instrument matches the actual construction effect

(2) Most of the relevant research is based on cement-stabilized gravel. Whether the parameters and test procedures of the vibration test method are suitable for crushing gravel still needs a lot of research

(3) At present, with regard to the strength design standard of the vibration design method, the strength design standard of the semi-rigid base material of the current specification is still adopted in most places. This standard is proposed based on the heavy compaction method and the static pressure method, resulting The dosage of cement is low, and the integrity of the pavement core cannot be guaranteed

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