Method for reducing swell potential of expansive clay mineral and expansive clayey soil with molecular level simulation

Patent metadata

Field	Value
Publication number	US-10024016-B2
Application number	US-201615177872-A
Country	US
Kind code	B2
Filing date	Jun 9, 2016
Priority date	Dec 23, 2015
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A method of reducing the swell potential of an expansive clay mineral. The method includes (a) carrying out a forcefield-modified molecular level simulation to determine an amount of a swelling reduction agent to be incorporated into the expansive clay mineral to form a swelling reduction agent incorporated expansive clay mineral with a reduced swell potential Si(ECM) that is no greater than a pre-set level T, wherein the swelling reduction agent comprises at least one cementation material of calcite, gypsum, and potassium chloride and/or at least one exchangeable cation of K+, Ca2+, and Mg2+, and wherein the forcefield-modified molecular level simulation comprises molecular mechanics, molecular dynamics, and Monte Carlo simulation techniques configured to simulate the reduced swell potential Si(ECM), and (b) incorporating the amount of the swelling reduction agent into the expansive clay mineral to form the swelling reduction agent incorporated expansive clay mineral.

First claim

The invention claimed is:

1. A method of reducing the swell potential of an expansive clay mineral, the expansive clay mineral having a water content and a cation exchange capacity (CEC), the method comprising:
(a) carrying out a forcefield-modified molecular level simulation to determine an amount of a swelling reduction agent to be incorporated into the expansive clay mineral to form a swelling reduction agent incorporated expansive clay mineral with a reduced swell potential S i(ECM) that is no greater than a pre-set level T,
wherein the swelling reduction agent comprises at least one cementation material selected from the group consisting of calcite, gypsum, and potassium chloride at a first weight percent of the amount of the swelling reduction agent, and/or at least one exchangeable cation selected from the group consisting of K + , Ca 2+ , and Mg 2+ at a second weight percent of the amount of the swelling reduction agent,
wherein the sum of the first weight percent and the second weight percent is no greater than 100%,
wherein the forcefield-modified molecular level simulation comprises molecular mechanics, molecular dynamics, and Monte Carlo simulation techniques configured to simulate the reduced swell potential S i(ECM) of the swelling reduction agent incorporated expansive clay mineral based on the water content as an initial water content and CEC of the expansive clay mineral, the at least one cementation material at the first weight percent of the amount of the swelling reduction agent, and/or the at least one exchangeable cation at the second weight percent of the amount of the swelling reduction agent, and
(b) incorporating the amount of the swelling reduction agent into the expansive clay mineral to form the swelling reduction agent incorporated expansive clay mineral.

2. The method of claim 1 , wherein the CEC of the expansive clay mineral lies in the range of 40-150 meq/100 g dry expansive clay mineral.

3. The method of claim 1 , wherein the forcefield-modified molecular level simulation comprises a modified forcefield according to the following table:

Atom Types

Atom

type
Atom
Atomic mass
Coordination
Remarks

Na
Na
22.99000
0
sodium

Mg6 + 2
Mg
24.31000
6
magnesium, octahedral, +2

oxidation state

Al6
Al
26.98150
6
aluminium, octahedral

Si3
Si
28.08600
3
silicon, tetrahedral

K_
K
39.94800
0
potassium

Ca6 + 2
Ca
40.08000
6
calcium, octahedral, +2

oxidation state

Diagonal vdw

Atom

type
Lennard Jones
Radius (A)
Well depth (kcal/mol)

Na
LJ_6_12
2.6378
0.1301E+00

Mg6 + 2
LJ_6_12
5.9090
0.9029E−06

Al6
LJ_6_12
4.7943
0.1329E−05

Si3
LJ_6_12
3.7064
0.1841E−05

K_
LJ_6_12
3.7423
0.1000E+00

Ca6 + 2
LJ_6_12
3.3990
0.2380E+00

Atom typing rules

Atom

type
Atom
Hybridization
Formal oxidation state

Mg6 + 2
Mg
0
0
0
1

Al6
Al
3
0
0
1

Si3
Si
3
0
0
 1.

4. The method of claim 1 , wherein the swelling reduction agent comprises the at least one cementation material at the first weight percent of the amount of the swelling reduction agent, and wherein the forcefield-modified molecular level simulation comprises the steps of
(i) a molecular level simulation of water sorption onto a crystallite of the expansive clay mineral to form a water sorbed crystallite of the expansive clay mineral with the water content of the expansive clay mineral as the initial water content,
(ii) a molecular level simulation of sorption of the at least one cementation material in an amount proportional to the f

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Ahmed Habib Ur-Rehman
• Abduljauwad Sahel Nishat
• Dogan Ahmet Umran

Classifications

• C09K17/06

  Calcium compounds, e.g. lime · CPC title

• C04B33/1315

  Non-ceramic binders · CPC title

• E02D31/10

  against soil pressure or hydraulic pressure {(anchored foundations E02D27/50; joint sealings for use under hydraulic pressure E02D31/04)} · CPC title

• C04B2235/77

  Density · CPC title

• C09K17/02

  containing inorganic compounds only · CPC title