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Method for improving expansive soil by mixing nano-silica and ordinary cement

A technology of nano-silica and ordinary cement, applied in the field of geotechnical engineering, to achieve short-term strength improvement, large application space, important green innovation and engineering application value

Inactive Publication Date: 2018-03-16
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] At present, for the incorporation of nano-SiO in expansive soil 2 There are relatively few studies on cement, which are limited to the modification of cement-based materials and the improvement of concrete performance.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] An artificially configured expansive soil is made of kaolin and bentonite at a dry mass ratio of 10:1, LL=58.3, PL=26.4, PI=31.9, and the 1-D free expansion rate is 35%.

[0017] Cement: P.O.32.5 Ordinary Portland Cement.

[0018] Nano silica, average particle size 30nm±5nm, apparent density 40-60g / L, SiO 2 Content ≥99.5%, specific surface area 200±10m 2 / g.

[0019] The material proportions of nano silicon dioxide and cement are 1% and 4% of the dry mass of the soil.

[0020] Carry out indoor standard compaction test on the expansive soil that needs to be improved to determine the optimal water content and maximum dry density of the soil;

[0021] Add water to the dry expansive soil to the final water content state, stir well, and maintain for 24 hours;

[0022] Ordinary Portland cement and nano silica are fully stirred and mixed, and then fully mechanically mixed with expansive soil with optimal water content; then compacted in 4 layers in the triaxial sample form...

Embodiment 2

[0026] Nanyang expansive soil is taken from a highway project, which is medium expansive soil, PL=24.2, LL=59.8, PI=35.4, and the one-dimensional expansion rate is 10%.

[0027] Cement: P.O.32.5 ordinary cement.

[0028] Nano silica, average particle size 30nm±5nm, apparent density 40-60g / L, SiO 2 Content ≥99.5%, specific surface area 200±10m 2 / g.

[0029] The material proportions of nano silicon dioxide and cement are 1% and 4% of the dry mass of the soil.

[0030] Carry out indoor standard compaction test on the expansive soil that needs to be improved to determine the optimal water content and maximum dry density of the soil;

[0031] Add water to the soil to be reinforced as the roadbed to the optimal water content, and then fully perform mechanical stirring to make the water evenly distributed in the soil. Then add the mixed nano-silica powder and cement for full mechanical stirring, and mix evenly.

[0032] After mixing evenly, roll it with a horn mill 5 times, and...

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Abstract

The invention discloses a method for improving expansive soil by mixing nano-silica and ordinary cement, and belongs to the technical field of geotechnical engineering. A dry mass ratio of the nano-silica to the cement is 1:4, and the average particle size of the nano-silica is 25-35 nm. The expansive soil is medium expansive soil, and is evenly mixed with the nano-silica and cement in an optimumwater content state, and the obtained mixture is mechanically compacted according to the standard compaction work in order to achieve a maximum dry density corresponding to the optimum water content;and the mixture is cured for 28 d or more. The method can significantly improve the strength of the modified expansive soil and reduce the use amount of cement, has the advantages of environmental protection, energy saving and emission reduction, and has wide uses in the treatment of expansive soil-related geotechnical engineering disasters.

Description

technical field [0001] The invention belongs to the technical field of geotechnical engineering, and relates to the improvement and reinforcement technology of expansive soil, in particular to a new method for improving expansive soil by using cement and new nano material nano-silica. Background technique [0002] Expansive soil is a kind of special clay widely distributed all over the world. The main clay mineral of expansive soil is montmorillonite, so it exhibits the characteristics of water absorption expansion and loss of water contraction, which often causes damage to the structures and buildings built on it. Great harm brings huge economic loss, and this engineering problem has also been encountered in my country's South-to-North Water Diversion Project. Lime and cement are common methods used to strengthen and improve expansive soils and are widely used in industry. However, the improvement of the strength of expansive soil improved by lime is relatively limited, and...

Claims

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Application Information

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IPC IPC(8): C09K17/10C09K103/00
CPCC09K17/10C09K2103/00
Inventor 赵红华刘聪邱鹏王里德
Owner DALIAN UNIV OF TECH
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