Clay soil site preparation for building structures

Patent metadata

Field	Value
Publication number	US-10040996-B2
Application number	US-201715487153-A
Country	US
Kind code	B2
Filing date	Apr 13, 2017
Priority date	Dec 23, 2015
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A method of reducing the swell potential of an expansive clayey soil comprising expansive clay mineral(s) at a proportion of the total weight of the expansive clayey soil (PECM). The method includes (a) calculating a first amount of a swelling reduction agent to be incorporated into the expansive clayey soil to form a first swelling reduction agent incorporated expansive clayey soil with a reduced swell potential no greater than a pre-set level T with a nano-level constitutive modeling based on the water content and the CEC of the expansive clayey soil and PECM. The swelling reduction agent is at least one selected from calcite, gypsum, potassium chloride, a composition comprising exchangeable K+, a composition comprising exchangeable Ca2+, and/or a composition comprising exchangeable Mg2+, and (b) incorporating the first amount of the swelling reduction agent into the expansive clayey soil to form the first swelling reduction agent incorporated expansive clayey soil.

First claim

The invention claimed is:

1. A method of preparing a site having an expansive clayey soil comprising at least one expansive clay mineral to build a structure, the proportion of the weight of the at least one expansive clay mineral relative to the total weight of the expansive clayey soil being P ECM , the expansive clayey soil having a swell potential S soil at or above a pre-set limit T*, a first water content, and a cation exchange capacity (CEC) expressed in meq/100 g dry expansive clayey soil, the method comprising:
(a) assessing the site to build the structure by calculating a first amount of a swelling reduction agent to be incorporated into the expansive clayey soil to form a first swelling reduction agent comprising gypsum incorporated expansive clayey soil with a reduced swell potential S 1i(soil) that is no greater than the pre-set limit T* with a nano-level constitutive modeling based on the first water content as an initial water content (IWC) and the cation exchange capacity (CEC) of the expansive clayey soil,
wherein the first swelling reduction agent incorporated expansive clayey soil comprises a first swelling reduction agent incorporated at least one expansive clay mineral having a swell potential represented by S 1i(ECM) ,
wherein the swelling reduction agent is at least one selected from the group consisting of calcite, gypsum, potassium chloride, a composition comprising exchangeable K + , a composition comprising exchangeable Ca 2+ , and a composition comprising exchangeable Mg 2+ ,
wherein the incorporation of the first amount of the swelling reduction agent produces a modified total cohesive energy density (TCEDm) of the first swelling reduction agent incorporated at least one expansive clay mineral calculated according to Equation (6):
TCED m =0.0625(IWC) 3 −3.575(IWC) 2 +10.5(IWC)+2830+7100(C/0.1)+5050(G/0.2)+3010(KCl/0.1)+Ca(500)+Mg(300)+K(100)  (6)

where TCEDm=modified TCED, C=Proportion of calcite weight relative to the total weight of the first swelling reduction agent incorporated expansive clayey soil×P ECM , G=Proportion of gypsum weight relative to the total weight of the first swelling reduction agent incorporated expansive clayey soil×P ECM , KCl Proportion of potassium chloride weight relative to the total weight of the first swelling reduction agent incorporated expansive clayey soil×P ECM , Ca=Proportion of the number of calcium exchangeable cation relative to the total number of exchangeable cations in the first swelling reduction agent incorporated expansive clayey soil, Mg=Proportion of the number of magnesium exchangeable cation relative to the total number of exchangeable cations in the first swelling reduction agent incorporated expansive clayey soil, K=Proportion of the number of potassium exchangeable cation relative to the total number of exchangeable cations in the first swelling reduction agent incorporated expansive clayey soil, IWC=initial water content,
wherein the TCEDm of the first swelling reduction agent incorporated at least one expansive, clay mineral results in S 1i(ECM) calculated according to Equations (2), (3), and (5):
IDD={−2E-15(TCED m ) 4 +5E-11(TCED m ) 3 −5E-07(TCED m ) 2 +0.0023(TCED m )−1.5378}*1.85*(ABS(CEC−90)/90)  (2)

where IDD is initial dry density of the first swelling reduction agent incorporated at least one expansive clay mineral,
FDD=−2E-22(TCED m ) 6 +5E-18(TCED m ) 5 −6E-14(TCED m ) 4 +3E-10(TCED m ) 3 −7E-07(TCED m ) 2 +0.0005(TCED m )+0.3747  (3)

where FDD is final dry density of the first swelling reduction agent incorporated at least one expansive clay mineral when the first swelling reduction agent incorporated at least one expansive clay mineral reaches the swell potential S 1i(ECM) ,
S 1i(ECM) (%)=(FDD−IDD)/FDD*100  (5); and

 wherein the reduced swell potential of the first swelling reduction agent incorporated expansive clayey soil S 1i(soil) equals S 1i(ECM) ×P ECM , and then
(b) incorporating the first amount of the swelling reduction agent into the expansive clayey soil at the site to form the first swelling reduction agent incorporated expansive clayey soil, then
(c) building the structure on the expansive clayey soil at the site.

2. The method of claim 1 , wherein the gypsum is at least one selected from the group consisting of a white gypsum; a red gypsum, and a mixture of white gypsum and red gypsum.

3. The method of claim 1 , further comprising incorporating into the expansive clayey soil or the first swelling reduction agent incorporated expansive clayey soil a soil stabilizing composition comprising at least one material selected from the group consisting of ground granulated blastfurnace slag (GGBS), cement, resins, fly ash, lime, pozzolana, and a mixture of lime and pozzolana to form a stabilized expansive clayey soil or a stabilized first swelling reduction agent incorporated expansive clayey soil.

4. The method of claim 3 , wherein the swelling reduction agent comprises gypsum, the soil stabilizing composition comprises ground granulated blastfurnace slag (GGBS), wherein a mixture of the gypsum and the GGBS is incorporated into the expansive clayey soil, and wherein the weight ratio of the gypsum: the GGBS in the mixture lies in the range of 1:3 to 3:2.

5. The method of claim 3 , wherein the soil stabilizing composition further comprises lime to adjust the pH of the mixture of the gypsum and the GGBS to be greater than 10.5.

6. The method of claim 1 , wherein the at least one expansive clay mineral is at least one selected from the group consisting of smectite, bentonite, montmorillonite, beidellite, vermiculite, attapulgite, nontronite, illite, and chlorite.

7. The method of claim 1 , wherein the expansive clayey soil further comprises sand and the method further comprises removing all or a portion of the sand from the expansive clayey soil prior to the incorporating the first amount of the swelling reduction agent into the expansive clayey soil to form the first swelling reduction agent incorporated expansive clayey soil.

8. The method of claim 1 , wherein the structure is selected from the group consisting of a building foundation, a railway line foundation, a pipe, a footing, a landfill liner, a nuclear waste storage containment liner, a swimming pool, a wall, a driveway, a road, a pavement, a basement floor, and a wellbore.

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Ahmed Habib Ur-Rehman
• Abduljauwad Sahel Nishat

Classifications

• C04B33/131

  Inorganic additives · CPC title

• C04B33/1315

  Non-ceramic binders · CPC title

• C09K17/10

  Cements, e.g. Portland cement · CPC title

• B09C1/08

  chemically · CPC title

• B09C2101/00

  In situ · CPC title