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Method for determining dry shrinkage coefficient of cement stabilized macadam

A technology of cement-stabilized crushed stone and dry shrinkage coefficient, applied in the field of traffic civil engineering, can solve the problems of beams that are difficult to maintain a complete square cross-section, beam-type specimens are easily damaged when demoulded, and beam-type specimens are formed and segregated. To achieve the effect of easy operation, accurate weighing and accurate calculation of water loss

Active Publication Date: 2018-10-12
HENAN ZHONGYUAN EXPRESSWAY +1
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] (1) Segregation is prone to occur when the beam-type specimen is formed, especially under the coarser design gradation, resulting in great variability in the test data
[0015] (2) Beam-type specimens are prone to damage when demoulding, and it is difficult to maintain a complete square section at both ends of the beam
[0016] (3) When weighing, the test piece is easy to drop slag, resulting in inaccurate weighing and inaccurate calculation of water loss

Method used

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  • Method for determining dry shrinkage coefficient of cement stabilized macadam
  • Method for determining dry shrinkage coefficient of cement stabilized macadam
  • Method for determining dry shrinkage coefficient of cement stabilized macadam

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] In this group of tests, old water-stabilized gravel fine aggregates were used, and the gradation of cement-stabilized gravel was determined by the recommended gradation in JTG / TF20-2015 of "Technical Rules for Construction of Highway Pavement Base" JTG / TF20-2015. Material Test Regulations "JTG E51-2009 Inorganic Binder Stabilized Materials Compaction Test Method Determine the optimum moisture content and maximum dry density of cement-stabilized gravel, and select the cement dosage.

[0062] According to the determined proportion of fine aggregate in the cement-stabilized crushed stone gradation, the dosage and water content of cement in the molded cement mortar specimens were calculated. Specifically, based on the proportion of fine aggregate in the gradation, the cement content and water content determined under all aggregates are divided by the proportion of fine aggregate to calculate the cement dosage and water content in the formed cement mortar specimen.

[0063] ...

Embodiment 2

[0072] The difference from Example 1 is that this group of tests used fly ash crushed stone old material fine aggregate, under the overall blending mode, the content of fine aggregate below 4.75mm in the design gradation is about 40%, and the cement dosage of 3.5% Converted to cement mortar, it is 8.75%, and 5.5% cement dosage is converted to 13.75% in cement mortar; according to the maximum moisture content and maximum dry density of the molded specimen, the drying shrinkage test results measured after curing are shown in the following table 2-1 Show:

[0073] Table 2-1 Drying shrinkage test results of fly ash old material mortar

[0074]

[0075] From the results in Table 2-1, it can be concluded that the shrinkage coefficient of fly ash old material mortar first increases and then decreases and then increases with the increase of cement dosage. From the perspective of comprehensive shrinkage strain and shrinkage coefficient, the 0-4.75mm fine The optimum cement dosage f...

Embodiment 3

[0077] As a control group, new material fine aggregate was used in this group of experiments. Under the overall blending method, the content of fine aggregate below 4.75mm in the design gradation is about 40%, and the cement dosage of 3.5% is converted to 8.75% in cement mortar. , 5.5% cement dosage is converted to 13.75% in cement mortar; according to the maximum moisture content and maximum dry density of the molded specimen, the drying shrinkage test results measured after curing are shown in the following table 3-1:

[0078] Table 3-1 Drying shrinkage test results of new mortar

[0079]

[0080] From the results in Table 3-1, it can be concluded that the shrinkage coefficient of new fine aggregate decreases firstly and then increases and then decreases with the increase of cement dosage. From the perspective of comprehensive shrinkage strain and shrinkage coefficient, the fine aggregate of 0-4.75mm The cement-stabilized macadam with new limestone aggregate as the aggreg...

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Abstract

The invention relates to a method for determining the dry shrinkage coefficient of cement stabilized macadam. The method comprises the following successive steps: step 1, determining the grading, optimum moisture content and maximum dry density of the cement stabilized macadam and determining the dosage of cement; step 2, calculating the dosage and water content of cement in a cement mortar test piece; step 3, making the test piece, and subjecting the shaped cement mortar test piece to maintenance; step 4, after completion of maintenance, placing the test piece in a dry shrinkage chamber to measure dry shrinkage amount and water loss rate; and step 5, calculating the dry shrinkage strain and dry shrinkage coefficient of the cement mortar test piece according to the measured water loss rateand dry shrinkage amount, and evaluating the dry shrinkage performance of the cement-stabilized graded macadam.

Description

technical field [0001] The invention belongs to the technical field of traffic civil engineering, and relates to a method for determining the drying shrinkage coefficient of cement-stabilized gravel. Background technique [0002] Cement-stabilized macadam base has the characteristics of high strength, large bearing capacity, and good fatigue resistance. The proportion of cement-stabilized gravel used in the sub-base is as high as 2 / 3 or more. [0003] The disadvantages of cement-stabilized macadam base materials are low deformation resistance, high brittleness, and easy cracks due to dehydration shrinkage and temperature shrinkage. Such cracks will be reflected to the asphalt surface layer during the service life of the pavement, thereby deteriorating the structural performance of the pavement. How to control the cracking of the cement-stabilized gravel base material and ensure its durable and stable road performance has become an urgent problem to be solved. [0004] Dry...

Claims

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Application Information

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IPC IPC(8): G01N33/42
CPCG01N33/42
Inventor 李林涛徐世法李铁成胡超峰吴禹朱大治王晓晓王瑞涛
Owner HENAN ZHONGYUAN EXPRESSWAY
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