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Control method of mix ratio of low-strength backfill materials

A control method and low-strength technology, which is applied in the field of municipal engineering and highway engineering concrete engineering, can solve the problems of dust pollution, lack of a set of CLSM mixture, biological hazards, etc., and achieve good fluidity, good volume stability and durability performance, easy construction

Inactive Publication Date: 2014-06-25
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

So far, only some institutions or organizations have provided some recommended mix ratios, and there is no set of simple and easy CLSM mixture ratio design methods that can be selected for actual engineering design.
[0005] In addition, fly ash is one of the largest industrial wastes in my country. If a large amount of fly ash is not treated, it will generate dust and pollute the atmosphere, and the toxic chemical components (arsenic, lead, manganese, chromium, etc.) Will cause harm to human body and living things

Method used

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  • Control method of mix ratio of low-strength backfill materials
  • Control method of mix ratio of low-strength backfill materials
  • Control method of mix ratio of low-strength backfill materials

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] A building medium sand (fineness modulus of 2.3-3.0, average particle size of 0.35mm) is selected as the fine aggregate, and the fly ash is grade III fly ash (fineness not greater than 45%, water demand Ratio is not more than 115%, loss on ignition is not more than 15%, water content is not specified, sulfur trioxide content is not more than 3%), draw the fluidity curve as figure 2 shown.

[0056] From the fluidity curve, the minimum water consumption point is obtained around F / (F+S)=20%. Take the corresponding K1=20%, K2=0.288 for mix ratio design. The project is a general backfill project, take f 目标 =0.7Mpa.

[0057] The cement content was 2%, 4%, 6%, 8%, and 10%, respectively, and 5 sets of specimens were prepared, each with 3 parallel specimens (diameter 100mm, height 200mm). Put them in a standard curing room for curing, take them out of the curing room after 28 days and test the unconfined compressive strength of the specimens, the average values ​​of each gr...

Embodiment 2

[0069] Referring to Example 1, the minimum water consumption point is obtained around F / (F+S)=20%. Take the corresponding K 1 =20%, K 2 =0.288 for mix ratio design. If the above materials are used in non-excavable backfill projects, the design strength value is taken as f 目标 =1.1Mpa.

[0070] From the results in Table 1, we can see that f 目标 =1.1Mpa falls between intensity values ​​0.648 and 1.352, C 左 =4%, C 右 =6%, the corresponding compressive strength is f 左 =0.648Mpa, f 右 =1.352Mpa. Assuming that there is a linear relationship between strength and cement content, using linear interpolation, the 28-day strength is calculated as f 目标 The corresponding estimated cement content is:

[0071]

[0072] The obtained mix ratio is calculated by weight as cement content 5.3%, fly ash content 20%×(1-5.3%)=18.9%, sand content 1-5.3%-18.9%=75.8%, water content for K 2 =28.8%.

[0073] The mix ratio finally determined to be used is cement: fly ash: sand aggregate: water=5...

Embodiment 3

[0080] An alluvial island in the Yangtze River Estuary needs to bury optical fiber pipelines in order to improve the quality of telecommunications services on the island. Since the island is rich in fine sand from the Yangtze Estuary and relatively lacking in other aggregates, the fine sand from the Yangtze River Estuary was selected as the raw material aggregate component with an average particle size of 0.15mm. The cement is the most common 325-grade composite Portland cement in the local market, and the fly ash is the low-calcium third-grade ash of the power plant. The project is an ordinary road backfill project without special requirements. Therefore, the fluidity requirement of the road fluid backfill material is taken as the slump expansion degree of 28cm, and the design strength is taken as the 28-day unconfined compressive strength f 目标 =0.7MPa.

[0081] The specific process of mix ratio design is as follows:

[0082] Draw the flowability curve of the selected raw ...

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Abstract

The invention relates to the field of concrete engineering, in particular to a control method of the mix ratio of low-strength backfill materials. The control method comprises the following steps: (1) drawing a pulverized fuel ash and sandstone mixed flow curve: the horizontal ordinate of the flow curve is the ratio K1of replacing sandstone with pulverized fuel ash, the longitudinal ordinate is the water-solid ratio K2, and the flow curve is drawn according to the determined slump flow, wherein the water-solid ratio K2 is the ratio of water mass to the sum of cement mass, pulverized fuel ash mass and sandstone mass, and the ratio K1of replacing sandstone with pulverized fuel ash is the ratio of sandstone mass to the sum of sandstone mass and pulverized fuel ash mass; (2) determining the optimal water amount: the optimal water amount point is obtained, and the mixing amount of sandstone and pulverized fuel ash is determined; and (3), determining the mixing amount of cement: the mixing amount of cement and water is determined according to the compressive resistance required actually. CLSM (Controlled Low-Strength Materials) prepared by the control method are dense materials with little gaps, and convenient and easy to construct, the mixture is uniform, and excessive separation does not occur.

Description

technical field [0001] The invention relates to the field of municipal engineering and highway engineering concrete engineering, in particular to a method for controlling the mix ratio of low-strength backfill materials, which is used for the interface between three backs (abutment back, culvert back, retaining wall back) and structures. Dead corners, special parts that are difficult to compact and tamp. Background technique [0002] The excavation and backfilling of pipe trenches in municipal engineering or the backfilling of three backs (abutment back, culvert back, retaining wall back) in highway engineering, often due to the narrow construction space, traditional backfill materials (earth filler, graded sand and gravel filler) etc.) and the interface of the structure have dead angles, which makes it difficult to guarantee the quality of rolling and compaction, and often induces engineering diseases. [0003] Controlled Low-Strength Materials (CLSM) is a novel cementitio...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B28/04
Inventor 凌建明杨戈钱劲松张宏袁秋
Owner TONGJI UNIV
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