Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=yjge20 International Journal of Geotechnical Engineering ISSN: 1938-6362 (Print) 1939-7879 (Online) Journal homepage: http://www.tandfonline.com/loi/yjge20 Swelling potential, shrinkage and durability of cemented and uncemented lateritic soils treated with CWC base geopolymer Kennedy Chibuzor Onyelowe, Duc Bui Van & Manh Nguyen Van To cite this article: Kennedy Chibuzor Onyelowe, Duc Bui Van & Manh Nguyen Van (2018): Swelling potential, shrinkage and durability of cemented and uncemented lateritic soils treated with CWC base geopolymer, International Journal of Geotechnical Engineering, DOI: 10.1080/19386362.2018.1462606 To link to this article: https://doi.org/10.1080/19386362.2018.1462606 Published online: 03 May 2018. 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The test soil samples were preliminarily investigated and characterized under the laboratory conditions. Soils A, B and C were classified as A-2-7, A-2-6 and A-7, respectively, according to the AASHTO classification method. They were also classified according to USCS as poorly graded. Additionally, soils A and C were observed as having higher clay content than soil B. They were also classified as highly plastic with plasticity index above 17% and expansive. The free swell index and shrinkage tests showed that they had high potential for swelling and shrinkage. The treated soils show significant improvement in swelling, shrinkage, strength development and durability with CWCbGPC while the cemented soils failed in terms of shrinkage and durability, which proved that Portland cements have high potential for shrinkage with soil blends. The results of the laboratory study have shown that CWCbGPC and other geopolymer cements can totally replace Portland cements in civil engineering works more especially in the construction of hydraulically bound structures. Highlights • � CWC base GPC was synthesized in accordance with research findings • � Test soil sample was studied to determine the preliminary properties • � The test materials were studied and characterized to deter- mine their aluminosilicate content • � The CWC base GPC was applied in the stabilization of test soil • � The effect of CWC base GPC on swelling of the treated soil was studied • � The effect of CWC base GPC on shrinkage of the treated soil was studied • � The effect of CWC base GPC on durability of the treated soil was studied 1.  Introduction Crushed Waste Ceramic is a solid waste resulting from scrap loss of industrial production process, used ceramic plates or tiles and from handling centres, blended and recycled for reuse as a geosynthetic material. Because of the materials’ high alumi- nosilicates and pozzolanic content, it has found its reuse in the stabilization of earth materials adapted in contruction. Today’s infrastructural construction ranging from hydraulic struc- tures, pavements, sub-structures, etc. are exposed to variations in moisture and are known as hydraulically bound structures. Hydraulically bound materials (HBM) are natural or synthetic geopolymeric materials used in civil engineering works, which are subjected to moisture exposure throughout the life span of the infrastructure like the substructures or hydraulic structures e.g. dams, pools, ponds, retaining and gravity walls, and all sug- rade and subbase layers of pavements; rigid or flexible. During this state of exposure, the strength properties and consequently the durability of the foundation materials; natural or treated are affected by physical factors for instance capillary rise, suc- tion, swelling, shrinkage, erodibility, strength development, etc. (Onyelowe and Van Bui 2018a, 2018b). Geopolymer cements (GPC) have been studied and discovered to possess properties that could counterbalance the effects of exposure to these crit- ical factors, which include acids, extreme temperatures above 600 °C, salts, fire, heavy metals, and more importantly and more relevant to this research work is its property of withstanding exposure to moisture attack in a hydraulically bound medium a factor dependent on the moisture sensitivity of GPCs (Davidovits 2013), which eventually counts on the durability of the struc- tures. In the present research, GPC was synthesized from highly aluminosilicate bound materials under alkali-activator medium of NaOH + Na2SiO3. These materials rich in aluminosilicates are © 2018 Informa UK Limited, trading as Taylor & Francis Group KEYWORDS Durability; swelling and shrinkage; compacted lateritic soils; quarry dust; metallurgical slag; crushed waste ceramics; geopolymer ARTICLE HISTORY Received 24 February 2018 Accepted 3 April 2018 CONTACT  Kennedy Chibuzor Onyelowe  konyelowe@mouau.edu.ng, obiubachukwu@yahoo.com http://orcid.org/0000-0001-5218-820X mailto:konyelowe@mouau.edu.ng mailto:obiubachukwu@yahoo.com http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/19386362.2018.1462606&domain=pdf 2    K. C. ONYELOWE ET AL. Azizli 2016; Nikolov, Rostovsky, and Henk 2017). According to the above research findings, the aluminosilicate materials needed in the formation of GP are QD, MS and CWC under the reactive influence of Sodium Hydroxide (NaOH) and Sodium Silicate (Na2SiO3) as activators of a combined eco-friendly molar con- centration of 12 M. CWC contains high concentration of alu- minosilicates (Al-O-Si), maintains a highly pozzolanic property and serves the binding purpose in the synthesis of GP cement. These materials are blended in the proportion of 12% by weight Activator plus 22% by weight CWC plus 22% by weight QD plus 44% by weight MS. If the synthesis and use of GP cement can replace the need for OPC, the atmosphere must have been set free of the effect of releasing an equivalent tonne of CO2 emission into the atmosphere when cement is produced under higher energy consumptions. The atmosphere will eventually be set free of the solid waste or by-products of quarrying; QD (Onyelowe 2017a), by-products of metallurgical operations; MS, and the industrial solid waste; CWC by their application in the synthesis of GP cements and binders. The GP cement dry powder was stored for use and study as supplementary cementing material and total replacement for DOPC in the laboratory stabilization exercise. 2.2.  Experimental programme The following conventional tests were conducted on the natural test soils for the purpose of characterization and classification; Sieve Analysis Test: this was conducted with a vertically arranged sieve sizes mounted on an automatic shaker in accordance with BS 1377-2 and Nigerian General Specifiction (BS 1377-2 1990; NGS 1997), Compaction Test (Standard Proctor Test): this was conducted with 2016 ELE Automatic Compactor Machine in accordance with BS 1377-2, BS 1924 and NGS (BS 1377-2 1990; BS 1924 1990; NGS 1997), California Bearing Ratio Test (CBR): conducted with a 2015 S211 KIT CBR penetration machine, motorized 50kN ASTM used to load the penetration piston into the soil sample at a constant rate of 1.27 mm/min (1 mm/min to BS Spec.) and to measure the applied loads and piston’s pen- etrations at determined intervals in accordance with BS 1377-2, BS 1924 and NGS (BS 1377-2 1990; BS 1924 1990; NGS 1997), Atterberg Limit Test: was conducted using a 2013 Casagrande apparatus in accordance with BS 1377-2, BS 1924 and NGS (BS 1377-2 1990; BS 1924 1990; NGS (Nigeria General Specification/ Federal Ministry of Works and Housing) 1997), Specific Gravity Test was conducted by Pycnometer method in accordance with BS 1377-2, BS 1924 and NGS (BS 1377-2 1990; BS 1924 1990; NGS 1997), and Chemical Oxides Composition Test on the test soils and the test materials with XRF method in accordance with BS 1377-2 and NGS (BS 1377-2 1990; NGS 1997 and results were obtained. Furthermore, drying shrinkage cuboidal specimens (75 mm × 75 mm × 250 mm) were prepared from the geopolymer treated cemented and uncemented soils in accordance with AS 1012.13 (1992) which were compacted in three layers and cured for 24 h under the same laboratory conditions as the unconfined compressive strength specimens. Extra specimens were prepared for each mixture to ensure accuracy and forestall time loss due to accidents. In order to facilitate shrinkage measurements, gauge studs were installed in place at the centre of the ends cross sec- tions at the compaction stage. After the 24 h curing, the treated and untreated (control) specimens were dried for 4, 8, 12, 16, 20 quarry dust (QD), metallurgical slag (MS). QD was characterized and was discovered to possess great amount aluminosilicates. This is solid waste obtained from rock quarrying operation and its applications in the stabilization of soils have proven to improve the physico-mechanical properties of treated soil. QD is an amorphous waste product of rock quarry operation of highly aliminosilicate content (Fedrigo et al. 2017). This inorganic composition gives it the highly pozzolanic properties it pos- sesses (ASTM C618 2014; Nikolov, Rostovsky, and Henk 2017). Geopolymers on the same hand are produced from amorphous materials of highly auminosilicate content though with activator compounds of sodium or potassium, which enhances the attain- ment of a steady state with the stoichiometric release of Si and Al in the geopolymer synthesis chain leading to polycondensation (Nikolov, Rostovsky, and Henk 2017). In the present work, it is used as 50% replacement for FA in the synthesis of crushed waste ceramics (CWC) base GPC which was used to treat the test soil in the proportions of 5, 10, 15, 30, …, 60% by weight of the treated matrix. It is also important to note that the constituents of the GPC possess high pozzolanic properties (ASTM C618 2014). However, the synthesized product possessed cementing properties. GP cements, binders and concretes have found wide application in the infrastructures development industry and exhibits great use in solid waste management, construction and pavement foundation repair as geopolymer injection, toxic metal immobilization and coatings (BS 1377-2 1990; Laila et al. 2010; Gopal and Rao 2011; Hamidi, Man, and Azizli 2016; Bromley and Hadfield 2017). The application of blended CWC base geopoly- mer for the treatment of compacted soils was investigated in the present work. However in this work, the preliminary properties of test soils and their behaviour with crushed waste ceramic base geopolymer cement (CWCbGPC) treatment were studied with particular emphasis on; (i) the effect of GP cement addition on swelling potential of cemented and non-cemented lateritic soils, (ii) the effect of CWC base GPC on the drying shrinkage of the treated soils, and (iii) the effect of CWC base GPC on the strength development and durability of the treated soil. 2.  Materials preparation and methods 2.1.  Materials preparation The test soil samples were collected from Olokoro, Amaba and Ohia borrow pits. The test soils location maps are presented in Figure 1. The disturbed samples were collected, tapped to remove lumps, sun dried for 3 days and readied for use. CWC was col- lected as waste from ceramic depots sale outfits and companies. It was sun-dried, blended and stored in silo bags for the laboratory exercise. Dangote ordinary Portland cement (DOPC) was bought at Umuahia Timber market, Umuahia, Nigeria. QD was collected from rock quarry site, Amasiri, Afikpo, Ebonyi State. MS was collected from Delta Steel Company, Aladja, Warri, Nigeria. The CWC based Geopolymer (GP) was synthesized in accordance with the findings of Davidovits, Nikolov et al., Abdel-Gawwad and Abo-El-Enein, Hamidi et al., Akbari et al., Skvara et al. and Srinivasan and Sivakumar (Skvara, Jilek, and Kopecky 2005; Xiao et al. 2005; Davidovits 2013; Srinivasan and Sivakumar 2013; Akbari, Mensah-Biney, and Simms 2015; Yang and Li 2015; Abdel-Gawwad and Abo-El-Enein 2016; Hamidi, Man, and INTERNATIONAL JOURNAL OF GEOTECHNICAL ENGINEERING    3 and 24 h at room temperature. The length differences of the of the specimens were observed with a horizontal length comparator with a micrometer. For every round of drying period for the specimens, the length difference was measured and subtracted from its initial length and divided by the gauge length expressed as a percentage. The swelling test was conducted on the treated and untreated (Free Swell Test) soils in accordance with ASTM D4546-14 (ASTM D4546-14 2014). The CWCbGPC was varied between 5 and 60% in a steady increment of 5 and the treated soil specimens were cured for 3, 7, 14, 28, 36, 56 and 72 days to determine the swelling potential of the treated soils expressed as Equation (1). The loss of strength in immersion experiment was proposed in Series 800 (MCHW-V1, 2007) using the procedure given in Section 880.4. Two sets of test cylinders with a ratio of 1:1 (Diameter: Height) are prepared and air-cured for 14 days. While ‘Set A’ continued air-curing, ‘Set B’ of the test cylinders Figure 1. Olokoro, Amaba and Ohia test soils sample location maps. 4    K. C. ONYELOWE ET AL. rates and bonding potentials of the test materials, which sat- isfied that the material bonding is a very important factor in soil stabilization and strength development because the soil and the admixture need to form a homogeneous and cohesive bond (Rafat and Mohammad 2011). Material requirement for cementitious materials states that the sum of the oxide rates of SiO2, Al2O3, and Fe2O3 should not be less than 70%. The results of the analysed materials presented in Table 3 show that the percentage of SiO2 + FeO3 + Al2O3 for each of the materi- als is greater than 70%,which makes the test material samples highly pozzolanic (Rafat and Mohammad 2011). This property was of great advantage because it brought about a high degree of interaction, pozzolanic reaction, carbonation reaction and bonding between the studied soils and the synthesized GPC (ASTM C618 2014). 3.2.  Consistency behaviour of DOPC and CWCbGPC treated test soils Tables 4–6, Figures 4–6 summarized the consistency behaviour of the treated, cemented and uncemented lateritic soils with the were then cured for a further 14 days completely immersed in water. The compressive strength of these immersed samples (UCSimm) was determined together with that of the control spec- imens (UCScontrol). The control specimens are cured for 28 days at room temperature. All curing is undertaken at room temperature for the materials assessed in this research work. The mixture is considered to be durable if the following applies expressed as Equation (2) (Manual of Contract Documents for Highway Works-V1 2007) (Figure 2): where Sp = swelling potential in per cent; δh = amount vertical swell; h = initial height where UCSVS = relative volumetric stability, which is assumed to be durable if ≥80%. ID = durability index. 3.  Results and discussion 3.1.  General behaviour and classification of test materials The results of the experimental programme have been pre- sented in tables and graphs in the following pages. Test soil samples were investigated and characterized under the labora- tory conditions with the preliminary test as shown in Tables 1 and 2 and Figure 3. Soils A, B and C were classified as A-2-7, A-2-6 and A-7 groups, respectively, according to the AASHTO classification method (AASHTO 1993). They were classified according to USCS as poorly graded (GP). Additionally, soils A and C were observed as having higher clay content than soil B and higher free swell index (FSI) while soils B and C have higher potential for shrinkage with a shrinkage limit (SL) of 7%. They were also classified as highly plastic with plasticity index above 17% and expansive. Table 3 presents that the test materials have high aluminosilicate content and possess poz- zolanic properties (ASTM C618 2014). Table 3 shows the oxide (1)Sp = �h h x 100 (2)UCSVS(ID) = UCSimm UCScontrol x 100 1 ≥ 80% 5% Dangote Ordinary Portland Cement DOPC Quarry Dust Test Soil Samples Ground Granulated Blast Furnace Slag (GGBSF) Activators (NaOH, Na2SiO3) Crushed Waste Ceramics (CWC) Particle Size Distribution (PSD) Compaction California Bearing Ratio (CBR) Unconfined Compressive Strength (UCS) Atterberg limits CWC -Based GP GP -Treated Soils Swelling, Shrinkage, Loss of Strength on immersion Durability Tests Tabulated Results Figure 2. Schematic presentation of the experimental programme. Table 1. Basic properties of test soils. Property descrip- tion of test soils and units Behaviour Olokoro test soil (A) Amaba test soil (B) Ohia test soil (C) % Passing Sieve No 200 2.85 10 4.6 NMC (%) 12.1 13.49 14 LL (%) 40 46 64 PL (%) 18 21 36 PI (%) 22 25 28 SL (%) 8 8 7 FSI (%) 250 234 275 GS 2.6 2.43 2.12 AASHTO classifi- cation A-2-7 A-2-6 A-7 UCSC GP, CH GP GP, CH MDD (g/cm3) 1.76 1.85 1.80 OMC (%) 13.1 16.2 13.13 CBR (%) 12 13 8 Colour Reddish brown Reddish grey Reddish ash INTERNATIONAL JOURNAL OF GEOTECHNICAL ENGINEERING    5 But the behaviour reduced, obviously to ‘medium plastic’ con- sistency at the addition of the additive geopolymer material. At 5% DOPC to soils A, B and C, the PI reduced to 18, 21 and 25% respectively while beyond the addition of 20% CWCbGPC, the PI of the treated soils A and B reduced below 17% and beyond 25% CWCbGPC for soil C. This trend continued on further addition of the GPC. The hydration of the treated mixture and its increased calcium content from the MS has contributed to behaviour of the soil and also due to molecular rearrangement in the formation of transitional compounds. This improvement is due to the hydration of the highly aluminosilicate and poz- zolanic additives with the treated mixture, which reduced the PI consistently thereby producing a stiff mixture of stabilized soil. Also, the release of cations from the geopolymer material constituents during the cation exchange reaction has contributed to the behaviour of the treated soils. This behaviour agrees with Meegoda and Ratanweera (1994), which showed that if water is used as pore fluid, the influence of the mechanical factors would remain same with a general decrease in LL on addition of an admixture. However, if an organic fluid other than water is used, addition of different rates of CWCbGPC material. The natural soils had a highly plastic consistency of PI greater than 17%. Table 2. Particle size distribution (PSD) of test materials. Materials % Passing sieve (mm) 19 6.35 4.75 2.36 1.18 0.6 0.425 0.3 0.15 0.075 Pan Soil A – 100 89 67 59 44 36 22 15 2.85 0 Soil B – 100 91 82 63 50 39 28 21 10 0 Soil C – – 100 89 61 46 31 19 14 5 0 Quarry dust 100 89 44 23 18 15 14 12 5 2 0 CWC 100 97 86 70 55 45 33 28 25 21 0 GGBFS 100 96 82 76 63 54 47 39 24 19 0 10-1 100 1010 20 40 60 80 100 Particles diameter (mm) Soil A Quarry dust CWC GGBFS Pe rc en t f in er (% ) Soil B Soil C Figure 3. Particle size distribution of studied materials. Table 3. Oxides composition of the materials used in this paper. Notes: IR is Insoluble Residue, LOI is Loss on Ignition, CWC: Crushed Waste Ceramics. QD: Quarry dust, GGBFS: Ground granulated blast furnace slag. DOPC: Dangote ordinary Portland cement. Materials Oxides composition (content wt %) SiO2 Al2O3 CaO Fe2O3 MgO K2O Na2O TiO2 LOI P2O5 SO3 IR Free CaO Soil A 76.56 15.09 2.30 2.66 0.89 2.10 0.33 0.07 – – – – – Soil B 77.57 14.99 3.11 1.78 0.86 1.45 0.23 0.01 – – – – – Soil C 77.73 16.65 1.42 3.22 0.07 0.89 0.02 – – – – – – QD 63.48 17.72 5.56 1.77 4.65 2.76 0.01 3.17 0.88 – – – – CWC 64.45 24.14 0.25 1.3 0.28 3.69 2.51 0.18 1.09 – 2.11 – – GGBFS 33.45 12.34 42.10 0.05 11.45 – – – 0.21 – – – 0.40 DOPC 21.45 4.45 63.81 3.07 2.42 0.83 0.20 0.22 0.81 0.11 2.46 0.16 0.64 Table 4. Consistency limits of CWCbGPC treated soil A. Test Control 5% DOPC Consistency limits (%) of CWCbGPC % by weight treated soil A; A-2-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 wL 40 38 39 37 36 35 32 31 29 29 29 28 27 25 wp 18 20 19 18 18 18 16 17 17 19 22 24 23 21 Ip 22 18 20 19 18 17 16 14 12 10 7 4 4 4 Table 5. Consistency limits of CWCbGPC treated soil B. Test Control 5% DOPC Consistency limits (%) of CWCbGPC % by weight treated soil B; A-2-6/GP 5 10 15 20 25 30 35 40 45 50 55 60 wL 46 44 42 40 39 38 38 36 34 31 28 25 22 18 wp 21 23 18 17 17 18 22 23 23 22 21 22 19 15 Ip 25 21 24 23 22 20 16 13 11 9 7 3 3 3 6    K. C. ONYELOWE ET AL. required pavement thickness; wearing course  +  base course, hence a cost effective and durable pavement construction as a hydraulically bound structure (Gidigasu and Dogbey 1980; Fwa 2006; Gopal and Rao 2011). 3.3.  Compaction behaviour of DOPC and CWCbGPC treated test soils The compaction behaviour of the CWCbGPC treated soils were observed to improve in terms of dry density and OMC as pre- sented in Tables 7-9, Figures 7-9. There was an increase in the maximum dry density at 5% by weight addition of DOPC with a corresponding reduction in the OMC, while there was a con- sistent increase in MDD and associated decrease in OMC with the varied addition of the CWCbGPC. There was a possibility that the formation of new compounds occurred which conse- quently led to the increase in the MDD with addition of the CWCbGPC. This behaviour may also be due to cation exchange reactions, flocculation, polycondensation and the filling of the voids within the soil matrix thereby improving the porosity and in addition, the flocculation and agglomeration of the clay par- ticles due to polarization, release and exchange of ions (Gidigasu and Dogbey 1980; Osinubi, Bafyau, and Eberemu 2009; Fedrigo et al. 2017). The trend is in conformity with the results reported by (Onyelowe 2017a). An explanation that was offered for this trend is that there was increasing desire for water, which com- mensurate with the higher amount of CWCbGPC because more water was required for the dissociation of constituents with Ca2+ and OH- ions to supply more Ca2+ for the cation exchange reac- tion (Rafat and Mohammad 2011). The decrease in the OMC with increased proportions of CWCbGPC content might be due to cation exchange that also caused the flocculation of clay parti- cles. Moreover, the GPC constituents or test materials are highly pozzolanic materials and require water for hydration thereby improving the strength gain and the durability of the treated soils. 3.4.  Swelling potential of DOPC and CWCbGPC treated test soils The vertical swell behaviour of the DOPC and CWCbGPC treated soils were presented in Tables 10–12, Figures 10–12 which repre- sent soils A, B and C, respectively. Both control experiments, and the treated exercises showed a consistent increase in the swelling potential with the curing time. Conversely, the swelling potential decreased with increase in the addition of CWCbGPC. With soil A, it is observed that at 55 and 60% addition of CWCbGPC, the swelling potential reduced between 56 and 72  days of curing from 2.9 to 2.3% and between 3 and 7 days of curing time from the physical properties of the fluid such as viscosity and density would influence the LL. With the varying behaviour with the addition of CWCbGPC, it can be seen that the LL depends on mechanical factors other than the pore fluid viscosity and density (Gidigasu and Dogbey 1980; Masaki and Eiji 2006; Onyelowe and Agunwamba 2012; Olawale 2013; Akbari, Mensah-Biney, and Simms 2015; Onyelowe and Okafor 2015; Bromley and Hadfield 2017; Nikolov, Rostovsky, and Henk 2017) and to a higher degree on the physicochemical properties of carbonation, cation exchange and polycondensation. Consequently, the use of the treated soils as subgrade and base materials has been improved by the presence of the CWCbGPC and achieved non-frost-sus- ceptible materials with PI less than 15; a very important function affecting the durability of pavements and other civil engineer- ing works founded on soil (Smith and Smith 1998; Gopal and Rao 2011). The achieved subgrade improvement will reduce the Table 6. Consistency limits of CWCbGPC treated soil C. Test Control 5% DOPC Consistency limits (%) of CWCbGPC % by weight treated soil C; A-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 wL 64 60 61 54 50 47 42 36 31 26 18 18 15 12 wp 34 35 35 30 27 26 22 19 16 13 11 11 8 5 Ip 28 25 26 24 23 21 20 17 15 13 7 7 7 7 0 5 10 15 20 25 30 35 40 45 50 55 60 0 5 10 15 20 25 30 35 40 45 CWCbGPC Proportion by weight (%) C on si st en cy L im it s (% ) Plastic Limit, WP Liquid Limit, WL Plasticity Index, IP DOPC Proportion by weight (%) 0 5 10 15 20 25 30 35 40 45 50 55 60 Treated with DOPC Treated with CWCbGPC soil A Figure 4. Consistency limits of treated soil A. 0 5 10 15 20 25 30 35 40 45 50 55 60 0 5 10 15 20 25 30 35 40 45 50 CWCbGPC Proportion by weight (%) C on si st en cy L im its ( % ) Plastic Limit, WP Liquid Limit, WL Plasticity Index, IP DOPC Proportion by weight (%) 0 5 10 15 20 25 30 35 40 45 50 55 60 Treated with DOPC Treated with CWCbGPC soil B Figure 5. Consistency limits of treated soil B. INTERNATIONAL JOURNAL OF GEOTECHNICAL ENGINEERING    7 to the formation of more hydration points. And as the concen- tration of hydration materials increased, the number of contact points between hydration materials also increased consequently forming a solid microstructure within the treated soils matrixes reducing swelling potential. On the other hand, the decrease in swelling potential might also be due to the CWCbGPC acting as fillers to reduce the porosity of the treated soils thereby reducing swelling potential. However, the increased swelling potential as a result of prolonged curing time or water exposure time could be due to the mobility of sodium and calcium ions at increased hours of curing which led to higher rate of geopolymerization thereby creating increased rise in moisture (Abdel-Gawwad and Abo-El-Enein 2016; Muthukumar, Sekar, and Shukla 2018). 1.8 to 1.5% which remained constant throughout the curing sequence, a behaviour attributable to the microscopic swelling where water dipoles are absorbed between platelets (Kayabali and Demir 2011; Pimentel 2015; Ghosh, Kumar, and Krishanu 2016; Hamidi, Man, and Azizli 2016; Hariz et al. 2017). But in the case of soils B and C, it recorded a consistent increase with increase in curing time and a consistent decrease with increase in varied proportions of CWCbGPC. The reduced swelling potential along the increased CWCbGPC is due to the higher content of sodium silicates activator that tends to increase the release of Ca2+, Si4+ and Al3+ from the MS grains, which eventually speeded up geo- polymerization reaction rate. The Na2SiO3 acted as a nucleating site then increased with the amount of silicates released leading 0 5 10 15 20 25 30 35 40 45 50 55 60 0 10 20 30 40 50 60 CWCbGPC Proportion by weight (%) C on si st en cy L im its (% ) Plastic Limit, WP Liquid Limit, WL Plasticity Index, IP DOPC Proportion by weight (%) 0 5 10 15 20 25 30 35 40 45 50 55 60 Treated with DOPC Treated with CWCbGPC soil C Figure 6. Consistency limits of treated soil C. Table 7. Effect of CWCbGPC on the compaction of treated soil A. Test Control 5% DOPC Compaction of CWCbGPC % by weight treated soil A; A-2-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 MDD (g/cm3) 1.76 2.1 1.95 1.98 2.1 2.3 2.5 2.6 2.8 3.2 3.6 3.9 4.3 4.8 OMC (w)(%) 13.1 11.2 12.4 12.2 11.3 10.2 9.8 9.6 9.2 8.8 8.4 8.4 8.4 8.4 GS 2.6 2.8 2.7 2.9 3.1 3.2 3.4 3.5 3.7 3.8 3.8 3.9 3.9 4.2 Table 8. Effect of CWCbGPC on the compaction of treated soil B. Test Control 5% DOPC Compaction of CWCbGPC % by weight treated soil B; A-2-6/GP 5 10 15 20 25 30 35 40 45 50 55 60 MDD (g/cm3) 1.85 2.7 2.8 2.8 2.8 2.9 3.4 3.8 4.2 4.4 4.7 4.9 4.9 5.1 OMC (w)(%) 16.2 14.2 13.4 13.3 13.3 13.1 12.4 12.4 10.5 9.4 9.1 8.9 7.8 7.4 GS 2.43 2.5 2.7 2.9 3.2 3.4 3.6 3.7 3.8 3.9 4.3 4.5 4.7 4.8 Table 9. Effect of CWCbGPC on the compaction of treated soil C. Test Control 5% DOPC Compaction of CWCbGPC % by weight treated soil C; A-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 MDD (g/cm3) 1.80 1.85 1.85 1.87 1.88 1.94 1.98 2.13 2.4 2.7 2.9 3.1 3.6 3.9 OMC (w)(%) 13.13 12.5 12.2 12.1 11.6 10.4 9.8 9.6 9.2 8.7 8.5 8.2 8.0 7.6 GS 2.12 2.4 2.3 2.4 2.5 2.7 2.8 2.9 3.3 3.6 3.8 3.9 4.1 4.3 8    K. C. ONYELOWE ET AL. 3.5.  Drying shrinkage behaviour of DOPC and CWCbGPC treated test soils The drying shrinkage behaviour of the DOPC and CWCbGPC treated soils were presented in Tables 13–15, Figures 13–15 which represent soils A, B and C, respectively. Both control experi- ments, and the treated exercises showed a consistent increase in the swelling potential with the curing time. Conversely, the swelling potential decreased with increase in the addition of CWCbGPC. It is important to note at this stage that the lesser the shrinkage limits, the higher the potential for change in volume of soil both treated and untreated (Muthukumar, Sekar, and Shukla 2018). It is observed that the SL of the natural soil recorded 8% for soil A and 7% for soils A and B at 4 h of drying time which is considered to be undergoing severe volume change. This result improved with the increase in drying time. Unfortunately, with the addition of 5% DOPC, the value dropped to 5, 4 and 5% for soils A, B and C, respectively, which supports the high tendency for cemented soils to exhibit shrinkage. But in CWCbGPC soil blends under varied proportions, the SL consistently improved for the three test soils. This improvement was more pronounced with soil B which recorded a SL of 75% at 60% CWCbGPC after 24 h of drying time while soils A and C with higher clay contents (CH) recorded a SL of 65% under the same conditions, which shows that mineral composition is a factor to be considered because it affects shrinkage potentials of treated soils (Skvara, Jilek, and Kopecky 2005; Thakur and Singh 2005; Pimentel 2015). 3.6.  Strength development and durability of DOPC and CWCbGPC treated test soils The addition of the CWCbGPC to the test soils A, B and C consistently increased the compressive strength of the soils at a curing period of 28 days as presented in Table 16-18, Figures 16-18. Twenty Eight (28) days curing time was used here because strength development and durability of the treated matrix are the primary properties being evaluated. The soils mixed with the additive geopolymer maintained a consistent improvement, which showed that further addition will bring further increase in the strength of the treated soil. The presence of the geopoly- mer in the soils increased the strength properties of the blended mixture attributed to the physicochemical, aluminosilicate and highly pozzolanic properties of the CWCbGPC and to its ability to reduce adsorbed water thereby making soils with higher clay content to behave like granular soils. These result values satisfy the ‘very stiff ’ and ‘hard’ materials at 45, 50, 55 and 60% by weight addition of geopolymer material for soils A and B, and 50, 55 and 60% for soil C, a material condition for use as a sub-base material for pavement construction (Arioz et al. 2006; Davidovits 2013; ASTM C618 2014). Additionally, increase in the additives (CWCbGPC) concentration resulted in increasing of compres- sive strength at increased strain. By addition of CWCbGPC, the uncemented soil samples became denser by filling some voids in the soil samples structure. Also, the good dispersion of the geopolymer particles by addition of CWCbGPC led to a better filling of free spaces between the soil particles, which improved the porosity and more resistant soil samples. Additionally, the However, further increase in curing time increases the porosity of cemented matrix with a consequent increase in swelling potential values (Abdel-Gawwad and Abo-El-Enein 2016). 0 5 10 15 20 25 30 35 40 45 50 55 60 0 2 4 6 8 10 12 CWCbGPC Proportion by weight (%) M ax im um D ry D en si ty ( g/ cm 3 ) MDD OMC soil A Treated with DOPC Treated with CWCbGPC Gs 0 5 10 15 20 25 30 35 40 45 50 55 60 DOPC Proportion by weight (%) Sp ec if ic G ra vi ty (- ) 2 0 4 6 8 10 12 Figure 7. Compaction behaviour of treated soil A. 0 5 10 15 20 25 30 35 40 45 50 55 60 0 2 4 6 8 10 12 14 16 CWCbGPC Proportion by weight (%) M ax im um D ry D en si ty (g /c m 3 ) MDD OMC soil B Treated with DOPC Treated with CWCbGPC Gs 0 5 10 15 20 25 30 35 40 45 50 55 60 DOPC Proportion by weight (%) Sp ec if ic G ra vi ty (- ) 2 0 4 6 8 10 12 14 16 Figure 8. Compaction behaviour of treated soil B. 0 5 10 15 20 25 30 35 40 45 50 55 60 0 2 4 6 8 10 12 14 CWCbGPC Proportion by weight (%) M ax im um D ry D en si ty (g /c m 3 ) MDD OMC soil C Treated with DOPC Treated with CWCbGPC Gs 0 5 10 15 20 25 30 35 40 45 50 55 60 DOPC Proportion by weight (%) Sp ec if ic G ra vi ty (- ) 2 0 4 6 8 10 12 14 Figure 9. Compaction behaviour of treated soil C. INTERNATIONAL JOURNAL OF GEOTECHNICAL ENGINEERING    9 This was a test conducted on the DOPC and CWCbGPC mate- rials treated soils for use in pavement construction and other Geotechnical engineering works as a moisture (hydraulically) bound material (HBM) (Fwa 2006). The control test showed that the untreated natural soils were not durable with a durability potential of 72.80, 79.4 and 69.3%, respectively less than 80% while the cemented soil gave a durability potential of 66.7, 77.3 and 64.6%, respectively (Osinubi 2000; Osinubi, Bafyau, and increase in CWCbGPC concentration increased the intercon- nection between soil particles and produced more homogenous compressible material. Therefore, the CWCbGPC had a consid- erable effect on increasing the unconfined compressive strength of the uncemented test soils. Tables 19–21, Figures 19–21 has presented the loss of strength on immersion test results and the durability potential of cemented and uncemented test soils treated with CWCbGPC. Table 10. Effect of CWCbGPC on the swelling potential of treated soil A. Curing time (days) Control 5% DOPC Swelling potential (%) of CWCbGPC % by weight treated soil A; A-2-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 0 4.5 2.5 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.2 1.5 1.5 1.5 3 5.9 4.2 3.5 2.8 2.7 2.7 2.7 2.7 2.7 2.7 2.4 2.2 2.2 1.8 7 7.8 5.8 4.2 3.1 2.9 2.9 2.9 2.9 2.9 2.9 2.7 2.5 2.3 1.5 14 8.3 6.6 5.1 4.4 3.1 3.1 3.1 3.1 3.1 3.1 2.9 2.7 2.5 1.5 28 9.6 7.2 6.7 4.8 4.5 4.5 4.5 4.5 4.5 4.5 3.2 2.9 2.6 1.5 56 10.5 8.9 7.7 5.2 4.9 4.9 4.9 4.9 4.9 4.9 4.5 3.1 2.9 1.5 72 14.2 9.6 8.4 7.5 6.2 6.2 6.2 6.2 6.2 6.2 5.8 3.1 2.3 1.5 Table 11. Effect of CWCbGPC on the swelling potential of treated soil B. Curing time (days) Control 5% DOPC Swelling potential (%) of CWCbGPC % by weight treated soil B; A-2-6/GP 5 10 15 20 25 30 35 40 45 50 55 60 0 4.2 1.5 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.2 1.0 1.0 1.0 3 5.6 2.2 2.0 1.8 1.7 1.7 1.7 1.7 1.7 1.7 1.4 1.2 1.2 1.2 7 6.8 2.8 2.5 2.1 1.9 1.9 1.9 1.9 1.9 1.9 1.7 1.5 1.5 1.5 14 7.3 3.6 3.0 2.4 2.1 2.1 2.1 2.1 2.1 2.1 1.9 1.7 1.7 1.7 28 8.7 4.0 3.4 2.9 2.5 2.5 2.5 2.5 2.5 2.5 2.2 1.9 1.9 1.9 56 9.5 4.8 3.8 3.2 2.9 2.9 2.9 2.9 2.9 2.9 2.5 2.1 2.1 2.1 72 12.8 5.6 4.0 3.6 3.2 3.2 3.2 3.2 3.2 3.2 2.8 2.1 2.1 2.1 Table 12. Effect of CWCbGPC on the swelling potential of treated soil C. Curing time (days) Control 5% DOPC Swelling potential (%) of CWCbGPC % by weight treated soil C; A-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 0 5.5 4.5 4.4 3.4 3.2 2.8 2.4 2.2 1.5 1.5 1.5 1.5 1.5 1.5 3 6.0 5.2 4.5 3.8 3.7 3.4 3.1 2.5 2.0 1.5 1.5 1.5 1.5 1.5 7 6.2 5.8 5.2 4.1 3.9 3.8 3.5 2.8 2.4 1.5 1.5 1.5 1.5 1.5 14 8.5 7.6 6.1 5.4 4.1 4.0 3.6 3.2 2.8 1.5 1.5 1.5 1.5 1.5 28 9.8 8.2 7.7 6.8 5.5 5.2 4.2 3.8 3.2 2.5 2.5 2.5 2.5 2.5 56 11.5 8.9 8.7 7.2 6.8 6.2 5.5 4.3 3.8 2.5 2.5 2.5 2.5 2.5 72 14.8 9.6 8.7 7.5 7.0 6.6 6.1 5.2 4.8 2.5 2.5 2.5 2.5 2.5 0 7 14 21 28 35 42 49 56 63 70 2 4 6 8 10 12 14 Curing time (days) Sw el lin g Po te nt ia l ( % ) 10% CWCbGPC 5% CWCbGPC (15-40)% CWCbGPC 45% CWCbGPC 50% CWCbGPC 55% CWCbGPC 60% CWCbGPC Treated with DOPC Treated with CWCbGPC Soil A Control 5% DOPC Control Figure 10. Effect of CWCbGPC on the swelling potential of treated soil A. 10    K. C. ONYELOWE ET AL. 0 7 14 21 28 35 42 49 56 63 70 0 2 4 6 8 10 12 Curing time (days) Sw el lin g Po te nt ia l ( % ) 10% CWCbGPC 5% CWCbGPC (15-40)% CWCbGPC 45% CWCbGPC (50-60)% CWCbGPC Treated with DOPC Treated with CWCbGPC Soil B Control 5% DOPC Control Figure 11. Effect of CWCbGPC on the swelling potential of treated soil B. 0 7 14 21 28 35 42 49 56 63 70 0 2 4 6 8 10 12 14 Curing time (days) Sw el lin g Po te nt ia l ( % ) 10% CWCbGPC 5% CWCbGPC 15% CWCbGPC 35% CWCbGPC (40-60)% CWCbGPC Treated with DOPC Treated with CWCbGPC Soil C Control 5% DOPC 20% CWCbGPC 30% CWCbGPC 25% CWCbGPC Control Figure 12. Effect of CWCbGPC on the swelling potential of treated soil C. Table 13. Effect of CWCbGPC on the drying shrinkage of treated soil A. Oven time (hours) Control 5% DOPC Drying shrinkage (%) of CWCbGPC % by weight treated soil A; A-2-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 4 8 5 8 8 8 8 8 8 8 8 8 8 8 8 8 13 8 13 14 15 18 22 24 26 28 31 33 35 36 12 16 11 18 19 21 23 25 28 31 33 35 39 42 45 16 21 14 27 29 32 34 37 38 41 43 45 47 52 55 20 24 18 28 30 32 35 37 40 43 45 48 50 54 60 24 28 21 32 34 36 38 41 45 48 51 53 55 59 65 Table 14. Effect of CWCbGPC on the drying shrinkage of treated soil B. Oven time (hours) Control 5% DOPC Drying shrinkage (%) of CWCbGPC % by weight treated soil B; A-2-6/GP 5 10 15 20 25 30 35 40 45 50 55 60 4 7 4 7 7 7 7 8 8 8 8 8 8 8 8 8 10 5 10 12 15 17 28 32 39 42 45 48 50 55 12 12 7 13 15 17 19 36 40 45 48 50 53 55 58 16 15 9 17 19 22 24 38 45 48 55 58 60 62 64 20 18 11 19 21 24 27 41 48 52 58 60 65 67 70 24 20 12 22 25 27 32 45 53 55 60 65 68 70 75 INTERNATIONAL JOURNAL OF GEOTECHNICAL ENGINEERING    11 limits of durability (i.e. greater than 80%). This may be due to the fact that the CWCbGPC material showed strong pozzolanic and aluminosilicate properties because of the strong cations released at the adsorbed complex as to form a strong resistance to the effect of moisture on immersion. Also, the reaction between the soil anion and the geopolymer materials cations at the adsorbed complex contributed to the formation of fluccs and eventual den- sification, polycondensation and durable strength gain, which resisted the effect of absorption at the immersion of the treated test soils. Eberemu 2009; Onyelowe 2017a, 2017b, 2017c; Onyelowe and Van Bui 2018a, 2018b). The behaviour of the durability of the cemented soil is attributed to the high shrinkage and crack ten- dency of cement at the early life of cemented materials creating spaces for moisture to be absorbed thereby reducing the durabil- ity of cemented geotechnical facilities (Davidovits 2013). But on the addition of different rates of varied rates of CWCbGPC, the durability potential increased considerably and consistently. The matrix suction on immersion may have affected the strength of the CWCbGPC treated soil, but the results remained within the Table 15. Effect of CWCbGPC on the drying shrinkage of treated soil C. Oven time (hours) Control 5% DOPC Drying shrinkage (%) of CWCbGPC % by weight treated soil C; A-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 4 7 5 8 8 8 8 8 8 8 8 8 8 8 6 8 11 8 12 13 15 17 20 23 25 27 30 32 35 35 12 16 12 18 19 21 23 25 28 31 33 35 39 42 45 16 20 14 26 28 30 32 35 37 40 42 45 47 51 55 20 23 18 28 30 32 35 37 40 43 45 48 50 54 60 24 27 20 32 34 36 38 41 45 48 50 52 55 59 65 0 4 8 12 16 20 24 0 10 20 30 40 50 60 70 Drying time (hours) D ry in g Sh ri nk ag e (% ) 10% CWCbGPC 5% CWCbGPC 15% CWCbGPC 35% CWCbGPC 40% CWCbGPC Treated with DOPC Treated with CWCbGPCSoil A Control 5% DOPC 20% CWCbGPC 30% CWCbGPC 25% CWCbGPC 45% CWCbGPC 50% CWCbGPC 55% CWCbGPC 60% CWCbGPC Control Figure 13. Effect of CWCbGPC on the drying shrinkage of treated soil A. 0 4 8 12 16 20 24 0 10 20 30 40 50 60 70 80 Drying time (hours) D ry in g Sh ri nk ag e (% ) 10% CWCbGPC 5% CWCbGPC 15% CWCbGPC 35% CWCbGPC 40% CWCbGPC Treated with DOPC Treated with CWCbGPCSoil B Control 5% DOPC 20% CWCbGPC 30% CWCbGPC 25% CWCbGPC 45% CWCbGPC 50% CWCbGPC 55% CWCbGPC 60% CWCbGPCControl Figure 14. Effect of CWCbGPC on the drying shrinkage of treated soil B. 12    K. C. ONYELOWE ET AL. 0 4 8 12 16 20 24 0 10 20 30 40 50 60 70 Drying time (hours) D ry in g Sh ri nk ag e (% ) 10% CWCbGPC 5% CWCbGPC 15% CWCbGPC 35% CWCbGPC 40% CWCbGPC Treated with DOPC Treated with CWCbGPCSoil C Control 5% DOPC 20% CWCbGPC 30% CWCbGPC 25% CWCbGPC 45% CWCbGPC 50% CWCbGPC 55% CWCbGPC 60% CWCbGPC Control Figure 15. Effect of CWCbGPC on the drying shrinkage of treated soil C. Table 16. Effect of CWCbGPC on the compressive strength properties of treated test soil A at 28 days. Test strain (%) Axial stress (kN/m2) Axial stress (kN/m2)of CWCbGPC % by weight treated soil A; A-2-7/GP/CH Control 5% DOPC 5 10 15 20 25 30 35 40 45 50 55 60 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.05 95.5 96.4 96.4 108 124 142 148 152 157 160 172 198 198 198 0.1 115.5 118.5 118.8 128 143 165 170 178 182 186 198 221 221 221 0.15 118.6 120.4 121.4 132 165 186 188 196 200 206 223 243 243 243 0.2 135.7 138.4 138.6 140 176 197 200 214 219 224 248 265 265 265 0.25 143.5 149.5 149.6 160 185 210 218 223 228 234 264 285 285 285 0.3 147.7 156.6 157.5 170 194 218 221 229 235 238 284 302 302 302 0.35 149.8 162.8 162.4 185 200 228 230 238 245 249 302 334 334 334 0.4 154.4 174.3 174.9 198 208 234 238 241 248 256 322 356 356 356 0.45 158.5 182.5 183.1 201 219 245 250 258 262 276 338 376 376 376 0.5 159.9 188.5 188.6 206 226 258 262 274 285 288 348 389 389 389 0.55 162.7 190.6 191.8 218 234 261 268 281 295 297 355 406 406 406 0.6 168.0 192.4 192.9 222 248 278 281 289 299 307 371 420 420 420 0.65 171.5 196.5 197.4 228 256 289 292 299 308 312 388 448 448 448 0.7 175.6 198.4 198.8 232 265 301 310 317 318 321 400 462 462 462 0.75 178.9 201.4 202.4 238 276 316 321 326 328 331 424 482 482 482 0.8 180.6 202.5 202.8 243 286 324 328 332 337 340 442 501 501 501 0.85 183.5 203.4 203.8 245 291 342 348 351 362 369 462 519 519 519 0.9 184.6 205.3 205.8 255 298 354 361 369 376 380 480 537 537 537 0.95 185.9 206.5 207.0 261 302 368 371 382 393 396 500 556 556 556 1.00 196.6 208.1 208.0 267 316 380 392 398 400 405 520 570 570 570 Table 17. Effect of CWCbGPC on the compressive strength properties of treated test soil B at 28 days. Test strain (%) Axial stress (kN/m2) Axial stress (kN/m2)of CWCbGPC % by weight treated soil B; A-2-6/GP Control 5% DOPC 5 10 15 20 25 30 35 40 45 50 55 60 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.05 98 100 98 106 126 144 149 153 157 160 172 200 200 200 0.1 119 119 119 124 145 165 171 178 182 186 198 225 225 225 0.15 121 122 122 130 165 186 188 196 202 216 223 243 243 243 0.2 135 138 138 141 175 199 203 214 219 224 248 265 265 265 0.25 141 141 149 162 188 210 218 223 228 234 264 285 285 285 0.3 146 156 157 171 198 218 221 229 235 238 284 312 312 312 0.35 150 162 163 184 201 228 230 238 245 249 302 334 334 334 0.4 158 174 174 197 208 234 238 241 248 256 322 356 356 356 0.45 159 181 183 202 218 245 251 258 262 276 338 376 376 376 0.5 159 188 188 206 226 258 262 274 285 288 348 389 389 389 0.55 163 190 191 219 234 261 268 281 295 297 355 406 416 416 0.6 169 192 192 224 249 278 282 289 299 307 371 425 425 425 0.65 178 196 197 229 256 289 292 299 308 312 388 448 448 448 0.7 178 197 198 233 265 304 312 317 318 321 412 462 462 462 0.75 178 201 202 238 277 316 321 326 328 331 424 482 482 482 0.8 181 202 202 244 286 324 328 332 337 342 442 511 511 511 0.85 183 203 203 248 294 342 348 352 362 369 462 529 529 529 0.9 184 205 205 255 298 354 361 369 376 380 481 537 537 537 0.95 186 206 207 261 317 368 371 382 393 396 510 556 556 556 1.00 192 208 208 268 325 381 393 398 400 415 522 578 578 578 INTERNATIONAL JOURNAL OF GEOTECHNICAL ENGINEERING    13 Table 18. Effect of CWCbGPC on the compressive strength properties of treated test soil C at 28 days. Test strain (%) Axial stress (kN/m2) Axial stress (kN/m2)of CWCbGPC % by weight treated soil C; A-7/GP/CH Control 5% DOPC 5 10 15 20 25 30 35 40 45 50 55 60 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.05 90 102 91 94 96 97 99 99 120 134 154 165 173 185 0.1 97 116 99 103 104 105 107 107 132 148 165 188 198 205 0.15 100 118 102 105 106 107 109 109 145 159 178 208 216 228 0.2 103 120 105 107 108 109 111 111 154 168 198 224 242 255 0.25 105 123 108 110 113 115 117 117 161 176 213 243 265 284 0.3 109 126 111 113 114 117 118 118 174 186 226 258 278 301 0.35 113 129 114 118 119 121 123 123 185 198 238 268 296 328 0.4 117 130 119 120 122 123 125 125 195 210 248 277 312 345 0.45 121 132 123 124 125 126 129 129 208 220 254 298 328 365 0.5 123 134 126 129 130 132 133 133 219 235 269 312 337 378 0.55 127 138 129 132 133 135 137 137 225 246 284 326 349 394 0.6 130 145 130 135 136 137 139 139 234 265 296 338 354 409 0.65 134 148 135 138 139 139 142 142 245 278 307 348 361 423 0.7 139 150 140 143 144 145 147 147 258 288 316 356 377 437 0.75 142 153 144 146 148 149 152 152 267 296 325 364 381 454 0.8 148 155 149 152 156 158 159 159 272 316 338 372 398 469 0.85 150 169 152 154 157 159 163 163 286 328 345 381 417 472 0.9 154 170 156 164 168 169 171 171 294 342 358 400 428 484 0.95 164 185 166 176 178 179 182 182 298 354 366 420 434 491 1.00 176 190 178 180 182 184 189 189 306 366 375 442 440 505 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 100 200 300 400 500 600 Strain (%) A xi al S tr es s (k N /m 2 ) 10% CWCbGPC 5% CWCbGPC 15% CWCbGPC 35% CWCbGPC 40% CWCbGPC Treated with DOPC Treated with CWCbGPC Soil A Control 5% DOPC 20% CWCbGPC 30% CWCbGPC 25% CWCbGPC 45% CWCbGPC (50-60)% CWCbGPC Control Figure 16. Effect of CWCbGPC on the compressive strength properties of treated test soil A. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 100 200 300 400 500 600 Strain (%) A xi al S tr es s (k N /m 2 ) 10% CWCbGPC 5% CWCbGPC 15% CWCbGPC 35% CWCbGPC 40% CWCbGPC Treated with DOPC Treated with CWCbGPC Soil B Control 5% DOPC 20% CWCbGPC 30% CWCbGPC 25% CWCbGPC 45% CWCbGPC (50-60)% CWCbGPC Control Figure 17. Effect of CWCbGPC on the compressive strength properties of treated test soil B. 14    K. C. ONYELOWE ET AL. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 100 200 300 400 500 Strain (%) A xi al S tr es s (k N /m 2 ) 10% CWCbGPC 5% CWCbGPC 15% CWCbGPC 35% CWCbGPC 40% CWCbGPC Treated with DOPC Treated with CWCbGPC Soil C Control 5% DOPC 20% CWCbGPC 30% CWCbGPC 25% CWCbGPC 45% CWCbGPC 50% CWCbGPC Control 55% CWCbGPC 60% CWCbGPC Figure 18. Effect of CWCbGPC on the compressive strength properties of treated test soil C. Table 19. UCS loss of strength on immersion and the durability index of CWCbGPC treated soil A. Test Control 5% DOPC UCS and durability index of CWCbGPC % by weight treated soil A; A-2-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 28 days open air curing (kN/m2) 220.5 225 225 248 256 272 286 298 312 325 338 347 356 364 14 days open air curing + 14 days immersed curing (kN/m2) 160.5 150 185 220 232 256 269 281 298 312 325 330 338 342 Durability index (%) 72.8 66.7 82.2 88.7 90.6 94.1 94.1 94.3 95.5 96.0 96.2 95.1 94.9 94.0 Table 20. UCS loss of strength on immersion and the durability index of CWCbGPC treated soil B. Test Control 5% DOPC UCS and durability index of CWCbGPC % by weight treated soil B; A-2-6/GP 5 10 15 20 25 30 35 40 45 50 55 60 28 days open air curing (kN/m2) 215.4 220 225 234 242 258 269 278 290 312 324 344 356 388 14 days open air curing + 14 days im- mersed curing (kN/m2) 171 170 185 194 203 219 229 238 256 303 316 329 338 356 Durability index (%) 79.4 77.3 82.2 82.9 83.8 84.9 85.1 85.6 88.3 97.4 97.5 956 94.9 91.8 Table 21. UCS loss of strength on immersion and the durability index of CWCbGPC treated soil C. Test Control 5% DOPC UCS and durability index of CWCbGPC % by weight treated soil C; A-7/GP/CH 5 10 15 20 25 30 35 40 45 50 55 60 28 days open air curing (kN/m2) 180.5 198 201 228 245 252 267 285 302 324 324 324 300 300 14 days open air curing + 14 days immersed curing (kN/m2) 125 128 180 205 220 226 238 255 271 289 285 281 256 245 Durability index (%) 69.3 64.6 89.6 89.9 89.8 89.7 89.1 89.5 89.7 89.2 88.0 86.7 85.3 81.7 0 5 10 15 20 25 30 35 40 45 50 40 80 120 160 200 240 280 320 360 CWCbGPC Proportion by weight (%) U nc on fi ne d C om pr es si ve S tr en gt h (k N /m 2 ) Treated with DOPC Treated with CWCbGPC Soil A 28 days open air curing 14 days open air curing + 14 days immersed curing D ur ab ili ty I nd ex (% ) 40 80 120 160 200 240 280 320 360 Durability Index DOPC Proportion by weight (%) 0 5 10 15 20 25 30 35 40 45 50 Figure 19.  Effect of CWCbGPC on UCS loss of strength on immersion and the durability index – soil A. 0 5 10 15 20 25 30 35 40 45 50 40 80 120 160 200 240 280 320 360 CWCbGPC Proportion by weight (%) U nc on fi ne d C om pr es si ve S tr en gt h (k N /m 2 ) Treated with DOPC Treated with CWCbGPC Soil B 28 days open air curing 14 days open air curing + 14 days immersed curing D ur ab ili ty In de x (% ) 40 80 120 160 200 240 280 320 360 Durability Index DOPC Proportion by weight (%) 0 5 10 15 20 25 30 35 40 45 50 Figure 20.  Effect of CWCbGPC on UCS loss of strength on immersion and the durability index – soil B. INTERNATIONAL JOURNAL OF GEOTECHNICAL ENGINEERING    15 Notes on contributors Kennedy Chibuzor Onyelowe, is a lecturer at the Michael Okpara University of Agriculture, Umudike, Nigeria who has published widely in the area of soil stabilization, transport geotechnics and computational geotechnics. Duc Bui Van, is a lecturer at the Hanoi University of Mining and Geology, Hanoi who has published very good articles in the area of Geotechnical Engineering. Manh Nguyen Van, is a lecturer at the Hanoi University of Mining and Geology, Hanoi who has published very good articles in the area of Geotechnical Engineering. ORCID Kennedy Chibuzor Onyelowe   http://orcid.org/0000-0001-5218-820X References AASHTO (American Administration for State Highway Officials). 1993. Guide for Design of Pavement Structures, Washington, CA 20001, USA: AASHTO. Abdel-Gawwad, H. A., and S. A. 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(ii) � The swelling potential of the treated soils improved con- sistently with increased proportions of the CWCbGPC. (iii) � Similarly, the shrinkage limits improved consistently with increased and varied proportions of the GPC unlike the soil DOPC blend which deteriorated with addition of 5% DOPC for the test soils and gave cre- dence to the high shrinkage tendency of cemented matrixes. (iv) � The strength development and durability of the treated soil improved consistently also. But the durability of the cemented soils was impaired and showed that cemented soils under hadraulically bound medium or conditions or long moisture exposures are not durable as a result of the high shrinkage potential of Portland cements. Generally, the above exercise has shown that CWCbGPC can totally replace DOPC in the treatment of soils for hydraulically bound purposes; highway pavement foundations, airfield pave- ment foundations, substructures and other hydraulic structures for more durable structures resistant to heat or temperatures above 600C, acid attacks, sulphate attacks, fire, etc. and func- tioned well as fillers, which improved the porosity of the treated soils enhancing the densification, flocculation, polycondensa- tion, strength development and durability of the treated soils. Finally, having shown consistent progress in the durability index, it also shows that beyond the highest proportion and beyond the 28 days, CWCbGPC will stand these effects over time. Disclosure statement No potential conflict of interest was reported by the authors. 0 5 10 15 20 25 30 35 40 45 50 40 80 120 160 200 240 280 320 360 CWCbGPC Proportion by weight (%) U nc on fi ne d C om pr es si ve S tr en gt h (k N /m 2 ) Treated with DOPC Treated with CWCbGPC Soil C 28 days open air curing 14 days open air curing + 14 days immersed curing D ur ab ili ty In de x (% ) 40 80 120 160 200 240 280 320 360 Durability Index DOPC Proportion by weight (%) 0 5 10 15 20 25 30 35 40 45 50 Figure 21.  Effect of CWCbGPC on UCS loss of strength on immersion and the durability index – soil C. http://orcid.org http://orcid.org/0000-0001-5218-820X https://doi.org/10.1016/j.hbrcj.2014.06.0018 http://www.astm.org http://www.astm.org https://doi.org/10.1016/j.ijprt.2017.06.001 https://doi.org/10.1080/19386362.2016.1151621 https://doi.org/10.1016/j.proeng.2016.06.568 https://doi.org/10.1016/j.proeng.2016.06.568 16    K. C. ONYELOWE ET AL. Onyelowe, K. C., and D. 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C. Agunwamba. 2012. “Technical Note:Geotechnical Examination of the Geophysical Properties of Olokoro Borrow Site Lateritic Soil for Road Works.” Nigerian Journal of Technology 31 (3): 397–400. Onyelowe, K. C., and F. O. Okafor. 2015. “Review of the Synthesis of Nano-Sized Ash from Local Waste for Use As Admixture or Filler in Engineering Soil Stabilization and Concrete Production.” Journal of Environmental Nanotechnology. 4 (4): 23–27. doi:10.13074/ jent.2015.12.154167 https://doi.org/10.1080/19386362.2017.1422909 https://doi.org/10.1080/19386362.2017.1422909 http://140.118.105.174/jge/index.php http://140.118.105.174/jge/index.php https://doi.org/10.1007/978-1-4020-9139-1_26 https://doi.org/10.1007/978-1-4020-9139-1_26 https://doi.org/10.1155/2013/509185 https://doi.org/10.1051/matecconf/20179701021 https://doi.org/10.1139/T10-074 https://doi.org/10.1007/978-3-319-63570-5_4 https://doi.org/10.1016/j.cscm.2017.03.001 https://doi.org/10.11648/j.ijmsa.20130206.14 https://doi.org/10.1080/19386362.2017.1322797 https://doi.org/10.4172/2229-8711.1000220 https://doi.org/10.13074/jent.2015.12.154167 https://doi.org/10.13074/jent.2015.12.154167 Abstract Highlights 1. Introduction 2. Materials preparation and methods 2.1. Materials preparation 2.2. Experimental programme 3. Results and discussion 3.1. General behaviour and classification of test materials 3.2. Consistency behaviour of DOPC and CWCbGPC treated test soils 3.3. Compaction behaviour of DOPC and CWCbGPC treated test soils 3.4. Swelling potential of DOPC and CWCbGPC treated test soils 3.5. Drying shrinkage behaviour of DOPC and CWCbGPC treated test soils 3.6. Strength development and durability of DOPC and CWCbGPC treated test soils 4. Concluding remarks Disclosure statement Notes on contributors References