Construction method for using phosphogypsum in embankment improvement

Patent metadata

Field	Value
Publication number	US-11319676-B2
Application number	US-202016786041-A
Country	US
Kind code	B2
Filing date	Feb 10, 2020
Priority date	Feb 15, 2019
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

A construction and/or installation method for using phosphogypsum in embankment improvement includes preparing a phosphogypsum-containing embankment mixture, setting moisture content of an embankment mixture, paving a modified phosphogypsum-containing embankment, and reversely layering anti-seepage cushion layers from two sides of the embankment to the center of the embankment. The preparation of a phosphogypsum-containing embankment mixture can include the following: 90 parts by weight of phosphogypsum and 10 parts by weight of cement are weighted, uniformly mixed and stirred to obtain a base material mixture; and 2-4 parts by weight of sodium silicate is weighted and dissolved in water, and an obtained solution is added to the base material mixture to obtain the phosphogypsum-containing embankment mixture. The construction and/or installation method for using phosphogypsum in an embankment improvement can satisfy embankment strength and rebound modulus requirements, and can be widely applied to a filling-deficient area and an area with a relatively high yield of phosphogypsum solid wastes.

First claim

What is claimed is:

1. A construction method for using phosphogypsum in an embankment, comprising:
(1) preparing a phosphogypsum-containing embankment mixture, including:
weighing 90 parts by weight of phosphogypsum and 10 parts by weight of cement, and uniformly mixing and stirring the phosphogypsum and the cement to obtain a base material mixture; and
weighing 2-4 parts by weight of sodium silicate, dissolving the sodium silicate in water, and adding an obtained solution to the base material mixture to obtain the phosphogypsum-containing embankment mixture;

(2) mixing the phosphogypsum-containing embankment mixture with water, including:
acquiring a part of the phosphogypsum-containing embankment mixture by using an isostatic pressing method, adding water to prepare samples with different water content, and obtaining maximum dry density and optimal moisture content of the phosphogypsum-containing embankment mixture in a same compaction energy condition, wherein moisture content of the phosphogypsum-containing embankment mixture is defined as a mass percentage of water lost when heating is conducted at a temperature between 120-130° C. for 9-12 hours to form a dried phosphogypsum-containing embankment mixture at the temperature;

(3) adding water to the phosphogypsum-containing embankment mixture according to the optimal moisture content obtained in (2) above to make moisture content of the phosphogypsum-containing embankment mixture reach the optimal moisture content, to obtain an embankment filler, where mixing of the phosphogypsum-containing embankment mixture is conducted in a plantmix manner by using a stock bin of a cement stabilized soil mixing station and a forced mixer; and
where an anti-seepage cushion layer is an anti-seepage geotechnical cloth or an anti-seepage geomembrane with a thickness not less than 1.0 mm; and
(4) transporting the embankment filler to a construction site, and installing the embankment filler according to a method that includes:
1) leveling and compacting original ground, and layering a soil filler above a groundwater level and a surface water level, wherein a loose layering depth of each layer of laid soil filler is not greater than 40 cm, and compactness is not less than 90%;
2) layering a first anti-seepage cushion layer on a full section of a top surface of a compacted soil-filled embankment;
3) layering a first soil filler layer on a full section of the first anti-seepage cushion layer, wherein a loose layering depth of the first soil filler layer is not greater than 40 cm;
conducting compaction and densification on the first soil filler layer in a condition of optimal moisture content; and
layering a second anti-seepage cushion layer on a full section of the top surface of the first soil filler layer;
4) layering a second soil filler layer on a full section of the second anti-seepage cushion layer, wherein a loose layering depth of the second soil filler layer is not greater than 40 cm;
conducting compaction and densification on the second soil filler layer in a condition of optimal moisture content; and
layering a third anti-seepage cushion layer on a full section of the top surface of the second soil filler layer;
5) layering the phosphogypsum-containing embankment mixture on a full section of the top surface of the third anti-seepage cushion layer, wherein a loose layering depth of the phosphogypsum-containing embankment mixture is not greater than 40 cm;
conducting isostatic compaction and densification in a condition of optimal moisture content; reversely layering the third anti-seepage cushion layer from two sides of the embankment to the center of the embankment, wherein a layering width of the third anti-seepage cushion layer on each side along an embankment section direction is not less than 1.5 m; and
layering a fourth anti-seepage cushion layer with a same width as the third anti-seepage cushion layer on the third anti-seepage cushion layer;
6) layering the phosphogypsum-containing embankment mixture on the top surface of the phosphogypsum-containing embankment, wherein a loose layering depth of the phosphogypsum-containing embankment mixture is not greater than 40 cm;
conducting isostatic compaction and densification in a condition of optimal moisture content;
reversely layering the fourth anti-seepage cushion layer from two sides of the embankment to the center of the embankment, wherein a layering width of the fourth anti-seepage cushion layer on each side along the embankment section direction is not less than 1.5 m; and
layering a fifth anti-seepage cushion layer with a same width as the fourth anti-seepage cushion layer on the fourth anti-seepage cushion layer;
7) layering the phosphogypsum-containing embankment mixture on the top surface of the phosphogypsum-containing embankment, wherein a loose layering depth of the phosphogypsum-containing embankment mixture is not greater than 40 cm;
conducting isostatic compaction and densification in a condition of optimal moisture content;
reversely layering the fifth anti-seepage cushion layer from two sides of the embankment to the center of the embankment, wherein a layering width of the fifth anti-seepage cushion layer on each side along the embankment section direction is not less than 1.5 m; and
layering a sixth anti-seepage cushion layer with a same width as the fifth anti-seepage cushion layer on the fifth anti-seepage cushion layer;
8) continuously layering the phosphogypsum-containing embankment mixture according to the above method until reaching an upper embankment, wherein a loose layering depth of each layer of phosphogypsum-containing embankment mixture is not greater than 40 cm;
conducting isostatic compaction and densification in a condition of optimal moisture content; and
reversely layering an n th anti-seepage cushion layer on a full section of the embankment from its two sides to its center; and
9) layering a third soil filler layer on a full section of the n th anti-seepage cushion layer, wherein a loose layering depth of the third soil filler layer is not greater than 40 cm; and
conducting compaction and densification on the third soil filler layer in a condition of optimal moisture content, so as to form a filling embankment.

Assignees

• Inst Geology & Geophysics Cas

Inventors

• Li Zhiqing

Classifications

• E01C3/003 Primary

  characterised by material or composition used, e.g. waste or recycled material (E01C3/006, E01C3/04 and E01C3/06 take precedence) · CPC title

• C04B2111/00732

  for soil stabilisation · CPC title

• C04B28/26

  Silicates of the alkali metals · CPC title

• C04B28/14

  containing calcium sulfate cements {(gypsum-paper plates E04C)} · CPC title

• C04B28/143

  the synthetic calcium sulfate being phosphogypsum · CPC title