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Journal of Rock Mechanics and Geotechnical Engineering 7 (2015) 220e225

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Journal of Rock Mechanics andGeotechnical Engineering

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Full length article

Improvements of marine clay slurries using chemicalephysicalcombined method (CPCM)

Dongqing Wu*, Wenyu Xu, Romy TjuarChemilink R&D Centre, 20 Kranji Road, Singapore 739462, Singapore

a r t i c l e i n f o

Article history:Received 22 December 2014Received in revised form2 February 2015Accepted 5 February 2015Available online 20 February 2015

Keywords:Chemicalephysical combined method(CPCM)Soil improvementMarine clay (MC) slurryLand reclamationChemical stabilizationVacuum preloading (VP)Geo-bagsSurcharge

* Corresponding author. Tel.: þ65 96328896.E-mail address: wu@chemilink.com (D. Wu).Peer review under responsibility of Institute of R

nese Academy of Sciences.1674-7755 � 2015 Institute of Rock and Soil Mechanences. Production and hosting by Elsevier B.V. All righttp://dx.doi.org/10.1016/j.jrmge.2015.02.001

a b s t r a c t

In this paper, the effectiveness, applicability and validity of chemicalephysical combined methods(CPCMs) for treatment of marine clay (MC) slurries were evaluated. The method CPCM1 combineschemical stabilization and vacuum preloading (VP), while CPCM2 is similar to CPCM1 but includes boththe application of surcharge and use of geo-bags to provide confinement during surcharge preloading.The key advantage of CPCM2 using geo-bags is that the surcharge can be immediately applied on thechemically stabilized slurries. Two types of geo-bags were investigated under simulated land filling anddyke conditions, respectively. The test results show that the shear strength (cu) of treated slurry byCPCM2 is generally much higher than that by CPCM1. Besides, the use of CPCM2 can significantly reducethe treatment time due to the short drainage paths created by geo-bags. Overall, CPCM2 allows fasterconsolidation and higher preloading that help to achieve higher mechanical properties of the stabilizedslurry. There are consistent relationships between cU and water content of slurries treated by CPCM2.Several important observations were also made based on comparisons of experimental data.� 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by

Elsevier B.V. All rights reserved.

1. Introduction

Large-scale land reclamation projects have been undertakensince the last few decades in different countries and/or regionsacross the world. Limited suitable costal land combined with highincrease of economy and population has been the main reasonaccounting for this fast development. However, there are someconstraints concerning the increasing demand of land reclamationpractice. Aside from the availability of the landfill materials whichnormally use sands or hill-cut materials, another drawback is thedeeper and deeper water depth to be reclaimed. In the past, landreclamation works used to be carried out from depths of 5e10 m.However, in the current land reclamation practice, works have toventure deeper water of more than 15e20 m and thus will incurmuch higher costs.

Most projects in China used the method of vacuum preloading(VP) to improve dredged or very soft clays in coastal cities for landreclamation purpose. One concern raised from this practice is thelimited achievable ultimate bearing capacity, which is commonly

ock and Soil Mechanics, Chi-

ics, Chinese Academy of Sci-hts reserved.

60e80 kN/m2. The consequence of this limited bearing capacitymeans that it often requires further ground improvement, espe-cially for areas designated for heavy duty activities.

Another method to improve very soft clay materials is throughchemical treatment or stabilization (Zhang et al., 2008). Usingappropriate chemical additives, soil physical properties can beimproved so as tomeet engineering requirements, though this typeof chemical way is not used as common as VP or surcharge method.One successful record of chemical treatment application was re-ported for the construction of an international airport in Japan (Satoand Kato, 2002). Although there were evidences that chemicaltreatment method was successful for treating dredged clay mate-rials with low water contents, it has been widely acknowledgedthat chemical treatment is not effective to improve the dredgedclay slurries or marine clay (MC) with higher initial water contents(>(3e4)LL, LL is the liquid limit), even higher chemical dosage isused.

The chemicalephysical combined method (CPCM) is a brand-new academic and practical model incorporated with innovativemethodology proposed by Chemilink years ago (Wu et al., 2013a,b).The CPCM has provided a new development direction for thehigher effective and efficient improvement of very soft soils forinfrastructural construction, especially for land reclamation usingMC slurries. The concept of CPCM is proposed through the externalpreloading to trigger the discharge of water from chemically sta-bilized soft to very soft soils such as MC slurries or mixtures, andconsequently condense the consolidating structure like the

(a)

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1: Sand; 2: G

valve; 6: V

ample columns eo-textile; 3: Vertic

acuum control valve;

Air/

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7: Pressure meter; 8:

water separation

box

Vacuum pump

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Tubes; 9: Ruler

ntrol

D. Wu et al. / Journal of Rock Mechanics and Geotechnical Engineering 7 (2015) 220e225 221

compaction in the conventional chemical-soil stabilization(Suhaimi and Wu, 2003). The mixture of MC slurry and chemicaladditives will be compressed by squeezing water out so that themixture structure becomes denser with lower water content.Consequently, the chemical reactions will be more effective asmixture particles are moving closer to each other; thus strengthscan be greatly increased within relative shorter time. Chemilink SS-330 series were used in the CPCM to improve the properties of MCslurry. The predominant function is enhancing the chemical re-actions mainly including cementation; whilst speeding up sedi-mentation is a secondary function in which the chemical additivecan make the particles of MC flocculate together to become the claylumps. Several SS-331 sub-series, which were used in the experi-ments, are the similar products but with different minor chemicaladditives in order to achieve better geotechnical performances withthe used MCs.

Series of in-house tests have been conducted to evaluate thetechnical effectiveness and performance of CPCM to achieve higherstrengths of clay slurry materials. The chemically stabilized MCslurries preloaded by vacuum (called CPCM1) have presentedmuchhigher mechanical performances (Wu et al., 2013b), while a seriesof in-house tests on different MCs has proven that CPCM cansimilarly achieve several times higher shear strength within muchshorter time when compared with those of pure MC slurries onlyphysically consolidated by VP (Wu et al., 2013a). More physicalapproaches and combinations can be further explored and devel-oped for purposes of better performances, higher efficiency andwider applicable scope of CPCM. Aside from VP, the surcharge is themost conventional and commonly used preloading means to pro-vide a physically static force to remove water from chemicallystabilized soils. However, the surcharge is unable to be immediatelyapplied on the stabilized slurry due to its instability. In presence ofgeo-bags, the surcharge can be immediately applied on thechemically stabilized slurry contained in geo-bags (called CPCM2)without instability issue concerned. Two types of geo-bags in bothshapes of cylinder and long-beam were investigated under CPCM2to simulate land fill and dyke, respectively.

Although encouraging results were obtained by using both ap-proaches of CPCM1 and CPCM2 as presented in this paper, furtherstudy needs to be conducted especially to obtain better un-derstandings on some practical empirical relationships, moreappropriate physical approaches, and combinations for CPCM sys-tem that is still new. Nevertheless, the current findings and futuredevelopments of CPCM could provide more innovative solutions tothe challenge of effective improvement of clay slurry, especially forland reclamation purpose.

(b)

Fig. 1. Experimental setup of vacuum preloading application. (a) Sketch illustration ofvacuum preloading experiment, (b) Vacuum preloading experiments using large 3Dconsolidation cell.

2. CPCM1 incorporated with vacuum preloading

A typical Singapore MC from excavation was selected for CPCMand its basic properties are given in Table 1, where d is the diameter.

The MC used in the study sampled from the lower layer ofSingapore MC (Arulrajah and Bo, 2008) with the chemicalcomposition is typically composed of kaolinite and illite(Kamruzzaman, 2003). Large numbers of in-house tests using thethree-dimensional (3D) consolidation cells (inner diameter of

Table 1Basic properties of typical Singapore marine clay (MC).

Specificgravity, Gs

Initial density,g (kN/m3)

Natural watercontent, w (%)

Liquid limit,LL (%)

Plastic limit,PL (%)

Plasind

2.66 16 60 79 34 45

17 cm and height of 100 cm) were conducted to verify the effec-tiveness of CPCM1, which combines chemical treatment and VPwith drains to improve MC with higher initial water content.

Samples of the Singapore MC with initial water content rangingfrom2LL to 5LLwere firstlymixedwith various versions of chemicaladditives (Chemilink SS-330 sub-series products). Subsequently, VP(normally fixed pressure at 95 kPa) was applied to the samples.Fig. 1 shows the experiment setup of the VP application for CPCM1.

Significant vertical displacements were recorded during the VPapplication for all samples, ranging from 50% to 80% of their initialheights, due to the water being sucked out of the samples. Theshear strengths were determined using fall-cone tests on the

ticex, PI

Organiccontent (%)

Grain size distribution (%)

Sand(d > 0.075 mm)

Silt (0.075 mm >

d > 0.002 mm)Clay(d < 0.002 mm)

3.80 3 48 49

Fig. 3. Surcharge loading application on top of column-shape geo-bag filled withchemically treated MC.

D. Wu et al. / Journal of Rock Mechanics and Geotechnical Engineering 7 (2015) 220e225222

samples, and the corresponding water content determination wasconducted as per-conventionally by using oven. Fig. 2 shows thevalues of shear strengths and final water contents selected from thebetter performing results of MC-additives mixtures, in terms of themeasured shear strength under CPCM1 system.

The results and comparisons shown in Fig. 2 prove the effec-tiveness of this CPCM1 incorporatedwith VP and addition of SS-330sub-series products as chemical additives. As reference, the shearstrength of both the pure MCs with initial water contents from 2LLto 5LL and the MC mixed with cement are also presented in thesame figure. It seems that the addition of 4% cement did not helpmuch to improve the shear strength of the mixture due to thehigher water content (4LL) of MC samples. In contrast, SS-330 ad-ditives at similar dosage generally performed well to increase theshear strengths up to 2e3 times that of the pure MC; whilst thesimilar conclusion has been also derived using China Zhujiang MC(Wu et al., 2013a). Meanwhile, the final water content values weremostly higher than those of the pure MC samples. The initial watercontent did not seem to have clear effect on the final water content,while the higher additive dosage resulted in an increase in finalwater content. In fact, the chemically treated soil has lost its orig-inal properties and becomes another type of soil, called “trans-formed soil” and some details were discussed by Wu et al. (2013b).The micro-structure and its development of the transformed MChave been also investigated by Bao et al. (2015).

It is interesting to note that the addition of incinerated bottomash (IBA) in one sample resulted in a further increase in shearstrength. The reasons are mainly due to the bigger physical parti-cles of IBA compared with particles of MC and the chemical re-actions that probably include the pozzolanic reaction among IBA,MC and chemical additive mixture (called MC-IBA matrix). Theenvironmental impact due to the heavy metal leaching from thisMC-IBA matrix will be discussed in separate papers.

3. CPCM2 incorporated with surcharge and geo-bags

Compared with VP, physical surcharge is the most traditionaland typical preloading method. Since there is an instability issue ifapplying surcharge loading immediately on the very soft slurry, thegeo-bags (made of non-woven geo-textile) have been introduced asthe containers of slurries to be improved. The surcharge loadings inthe form of physical dead weights were immediately placed on topof the chemically treated MC slurries contained by geo-bags inorder to squeeze the water out rapidly so as to compress slurries’particles closer together in a relatively short period of time.

Two types of geo-bags were used: column-shape (or cylindricalshape) and beam-shape (also known as geo-tube). The idea offilling the MC-mixture into two different shapes of geo-bags is to

c u(k

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MC (2-5LL)

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MC(4LL)+8%SS-3

MC(5LL)+6%SS-331H

MC(5LL)+3%SS331C

331E + 20%IBA

31E

31H

31E

Fig. 2. Selected testing results under CPCM1.Note: Chemilink SS-330 series includes SS-331C, E, and H.

simulate different functions in land reclamation such as the fillingmaterial in a larger water depth, and the dyke or embankment. Inthis paper, the column-shape geo-bags used in the experimentshad a diameter of 10 cm and height of 30 cm; the beam-shape geo-bags had diameter of 10 cm and length of 100 cm.

Fig. 3 demonstrates the experimental setup during the sur-charge loading application of chemically treated MC filled in thecolumn-shape geo-bag with the surcharge loading on top of it.Fig. 4 shows a physical sample of the chemically treatedMC filled ingeo-tube, which was taken from the deep loading tank right afterCPCM2 process as well as a small soil sample after removing thegeo-tube material.

The typical Singapore MCs with the initial water content of 158%(2LL) and 6% (based on the dry weight of MC) of chemical additiveSS-331H were used in all CPCM2 tests in this study.

It should be noted that all tested samples were immersed in seawater during the whole CPCM2 process (one month loadingapplication period) to simulate the real application situation. Sub-sequently, after the samples have finished the pre-determined onemonth loading application period, geo-bags were cut open andthen fall-cone tests were conducted on theMC-matrix to obtain theshear strength values in conjunctionwith the water content values.The given one month time was expected to be sufficient to allowthe completion of physical consolidation for tested samples.

Fig. 5 shows the average of achieved strengths from both col-umn- and beam-shape samples (called CPCM2-Column and

Fig. 4. Beam-shape sample after 1-m CPCM2 process.

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CPCM2-Column CPCM2-Beam CPCM1

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Fig. 5. Shear strength vs. surcharge under CPCM2.

(kPa

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500 600

IBA

IBA

Fig. 7. Shear strength development of chemically stabilized MC slurries withoutpreloading.

D. Wu et al. / Journal of Rock Mechanics and Geotechnical Engineering 7 (2015) 220e225 223

CPCM2-Beam, respectively), alongside with the result obtainedfrom an identical sample under CPCM1 as a reference. Meanwhile,Fig. 6 presents the obtained shear strength versus correspondingwater content values.

Within surcharge ranges of 0e20 kPa, it can be seen that thesamples under CPCM2-Beam achieved higher strength comparedwith samples under CPCM2-Column. Furthermore, higher sur-charge load resulted in higher shear strength within the sameperiod of time as expected. On the other hand, the samples underCPCM1 achieved lower strength under significantly higher loadingmagnitude.

Since the tested MCs under CPCM2 were prepared under thesame initial water content (2LL), the same chemical additive (SS-331H) and the same dosage (6%), and also under relatively similarpreloading conditions such as loading values and drainage paths,the characteristics of these resulted transformed MCs are similar.

A clear trend-line envelop related to the shear strength valuesvs. water contents of these similar transformed MCs can also befound in Fig. 6. Lower water content values were obtained from thesamples with higher strengths, and vice versa. However, the rela-tionship between shear strength and water content seems to bemore sensitive toward the lower end of water content values,resulting in a large difference of strengths’ increment with minordecrease in the water content values. In other words, to reducewater content slightly by increasing preloading may result in a verysignificant increment of the shear strength.

Based on the findings from the studies of purely chemicallystabilized MC slurry (Figs. 7 and 8), it can be reasonably predictedthat the shear strength shown in Fig. 5 will further be increased bychemical reactions with elapsed time after the completion ofconsolidation, regardless of whether the surcharge being removed

Fig. 6. Shear strength vs. water content under CPCM2.

or not. It should also be noted that the samples under the sameconditions as those of CPCM2 tests can achieve an average strengthof 20 kPa within the same one month time due to chemical re-actions only (Fig. 7).

Therefore, the much higher shear strengths achieved underCPCM2, when compared with that of the chemically stabilized MCwithout preloading, have once again proven the validity andeffectiveness of CPCM method, as what CPCM1 did.

Generally speaking, the samples without preloading got verylimited consolidation effect and thus the achieved strengths shouldbe mostly gained from chemical reactions. If the slurry has a higherinitial water content (>(2e3)LL), the achievable shear strengthcould be extremely lower (Wu et al., 2013b).

4. Comparison and discussion on CPCM

4.1. Effectiveness of CPCM

Generally, the shear strength of a specific soil achieved upon thecompletion of the physical consolidation under a fixed loading is,more or less, limited (see Fig. 2). However, with introduction ofappropriate chemical additives, such strength can be significantlyincreased under CPCM1 and unlike pure soil case, the strength willcontinuously increase due to chemical reactions even after thecompletion of consolidation.

Similarly, at the pre-given initial conditions such as water con-tent, chemical additive and its dosage and within a fixed timeperiod, the shear strength could be limited (Fig. 5) or evenextremely lower if the initial water content is higher than (3e4)LL(Wu et al., 2013b). However, with the introduction of physicalloadings, the shear strength can be increased in such as 5-6 timeshigher than that without preloading at the same time period, whilethe shear strength will continuously increase because of chemicalreactions among this newly transformed soil. This is why the CPCMmethod has provided a new development direction in soilimprovement.

Fig. 8. Pure chemically stabilized MC samples under sea water.

0

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0 2 4 6 8 10 12 14

c u(k

Pa)

Time (month)Pure chemical reaction

CPCM2-Beam: MC+6%SS-331H

CPCM1: MC+6%SS-331H+24% IBA

CPCM1: MC+6%SS-331H

CPCM

Fig. 9. Strength development during and after CPCM.

D. Wu et al. / Journal of Rock Mechanics and Geotechnical Engineering 7 (2015) 220e225224

4.2. Drainage path

Fast consolidation is definitely crucial for CPCMmethod in orderto reduce the water as fast as possible and simultaneously makeparticles closer to each other. While this condition consequentlystrengthens the effectiveness of chemical reactions among the soilsto be improved in order to achieve much higher strengths within ashorter time, reducing the drainage path is an effective way tospeed up the consolidation.

In practice, VP application is combined with prefabricated ver-tical drains (PVD) to remove the water out. The PVD spacing isnormally ranging from 0.8 m to 1.2 m. A half of this spacing can alsobe interpreted as the drainage path or length. The longer drainagepath prolongs the time for the consolidation to be completed andtherefore reduce the effectiveness of chemical reactions. CPCM2, onthe other hand, uses the advantage of geo-bags to function as thecontainer of chemically treated MC initially in slurry form andloaded with physical surcharge to force the water out from theslurry. Since the water can be drained through all sides of geo-bagswhich also function as the filter depending on the shape and size ofgeo-bags, the drainage length can be adjusted to be shorter. Thisshorter drainage length will enable water to be squeezed out veryquickly and clay particles drawn closer together, which will makethe chemical additive to createmore effective bonds between thoseparticles so as to achieve higher strengths.

The final drainage length of CPCM2-Beam samples is basically15e25 mm; whilst that length for CPCM2-Column is 50e60 mm,which is 2e3 times that of CPCM-Beam. Comparison between thetwo lines of shear strength (cu) vs. surcharge (preloading) as shownin Fig. 5 indicates that the higher shear strength was achieved withthe shorter drainage path at the same preloading and timeconditions.

The shear strength and the corresponding water content of thesamples CPCM2-Beam were carefully determined after one monthtime along its vertical depth at central and two-end sections, wherethe vertical direction to both top and bottom surfaces is the maindrainage path. The measured shear strengths and water contentsalong the depth at all sections are almost the same, suggesting thecompletion of consolidation. But the measured data at the both endsections are slightly better than those at central sections. It could beinduced by the samples at both ends with a horizontal drainagepath in addition to the vertical drainage paths.

4.3. Preloading magnitude

Similarly, each cu-preloading line shown in Fig. 5 also confirmsthat under the same conditions, the higher preloading can producehigher shear strength during consolidation process, whichcomfortably tallies with the concept of conventional consolidationtheory. This is because the higher preloading can make clay parti-cles closer so as to strengthen chemical reactions inside soil to beimproved.

The drainage path looks more sensitive than the magnitude asshown in Fig. 5. For example, at the same surcharge of 10 kPa, theshear strength achieved in CPCM2-Beam is about 2 times that ofCPCM2-Column, while the drainage length of CPCM-Beam is just ahalf of or lesser than that of CPCM-Column.

4.4. Strength development during and after CPCM

Especially, when the initial water content is relatively lowerthan 2LL, the strength of the purely chemically stabilized soil canstill increase significantly to meet some basic engineering re-quirements (Fig. 7). However, with CPCM application at a properpreloading, the water content of the slurry can be easily reduced

much below 2LL first and then the strength will continuouslydevelopwith elapsed time due to the chemical reactions, regardlessof preloading.

In order to simulate the whole strength development process,three typical clay slurries or mixtures stabilized by the chemicaladditive are selected in combination with both processes of CPCMand then pure chemical reactions without physical loading asshown in Fig. 9. From this figure, it can be seen that the initialstrength increasing trend under CPCM is very fast and then be-comes relatively slower without preloading. Finally, the strengthafter a period (say several months) will remain stable or increase atan extremely slow rate as time increases. Such strength develop-ment is very similar to that of conventional soil stabilization orconcrete. This strength development prediction provides a prom-ising concept to predict the desirable strength using CPCM atrequired time during and after physical preloading. Furthermore,with such consideration of whole strength development process,the reclaimed land under CPCM can be designed for heavy-dutyfoundations for port and industrial purposes.

4.5. Overall bearing capacity of CPCM2 with geo-bags

In fact, unlike the CPCM1 case, the bearing capacity of CPCM2cannot be directly estimated merely based on the shear strength ofthe inside clay. The properties of the geo-bag as the container willalso play an important role in the estimation of the overall bearingcapacity of the CPCM2 system.

Although it is believed that the higher shear strength of thestabilized clay inside the geo-bag represents the higher bearingcapacity of the system, the capacity calculated only based on thesoil strengths will definitely underestimate the capacity of thewhole system.

Due to the nature of the CPCM system group discussed in thisstudy, CPCM1 could be used comfortably to improve the MC slurryfor large area of land reclamation, while CPCM2 may be moresuitable for areas with special requirements and/or purposes, suchas CPCM-Beam used for constructing dykes and CPCM-Columnused for construction at corners or at larger depths.

5. Conclusions

(1) The CPCM has been again proven by different preloadingmeans to be valid, effective and efficient. CPCM provides adevelopment direction incorporated with innovative method-ology for improvement of very soft soils for infrastructuralconstruction, especially for land reclamation using MC slurries.

(2) The most conventional surcharge preloading incorporatedwith geo-bags has been investigated to explore the mechanismand workability of CPCM, in addition to the currently popular

D. Wu et al. / Journal of Rock Mechanics and Geotechnical Engineering 7 (2015) 220e225 225

VP commonly incorporated with PVD. Based on the experi-mental data with surcharge preloading, the achieved shearstrength can be 4e5 times higher than that of the purelychemically stabilized slurry within one month time.

(3) The studies of CPCM show that the faster consolidation canresult in more effective chemical reactions and thus producehigher strength within a short period of time. Therefore, howto speed up the consolidation process at beginning of thewhole soil improvement process is the key factor for CPCMapplications tomaximize the achievable strength. Reducing thedrainage path or increasing the preloading magnitude can bedone to serve the purpose.

(4) Although a significant increase of shear strength is gained dueto the both physical consolidation and chemical reactionsduring the preloading application, the increase of shearstrength is also gained from the chemical reactions that willcontinue even after the removal of preloading. Thus bothstrength increments during and after CPCM application have tobe considered in the design of the desirable strength of thereclaimed land using CPCM at an appropriate time.

(5) Future studies and experiments, especially field applicationswith various full dimensions/scales need to be conducted to get abetter understanding on CPCMmethods, while some critical anduseful empirical relationships could be set up for guiding moreengineering practice. Furthermore, other possible physicalmeans such as dynamic compaction and the combinations withboth surcharge andVP should be explored and adopted in future.

Conflict of interest

The authors wish to confirm that there are no known conflicts ofinterest associated with this publication and there has been nosignificant financial support for this work that could have influ-enced its outcome.

Acknowledgement

The paper is based on experimental results from the R&Dproject, titled “Creating a Marine Clay Matrix with IncinerationBottom Ash (IBA) for Land Reclamation” (Wu et al., 2014), underthe Innovation for Environmental Sustainability (IES) Fund fromNational Environment Agency (NEA) of Singapore (ETO/CF/3/1).Authors would like to thank NEA for allowing them releasing thedata.

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Bao SF, Dong ZL, Mo HH, Wu DQ. Laboratory tests on new reinforcement technologyof newly hydraulic reclamation mud with high clay content. Rock and SoilMechanics 2015;36(1):61e7 (in Chinese).

Kamruzzaman AHM. Physico-chemical and basic engineering behavior of treatedclay. PhD Thesis. Singapore: National University of Singapore; 2003.

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Suhaimi HG, Wu DQ. Review of chemical stabilization technologies and applicationsfor public roads in Brunei Darussalam. The Journal of Road Engineering Asso-ciation of Asia & Australia 2003;10(1):42e53.

Wu DQ, Dong ZL, Xu WY. Application of the chemicalephysical combined methodin land reclamation using marine clays from seabed. Chinese Journal of RockMechanics and Engineering 2013a;32(9):1379e784 (in Chinese).

Wu DQ, Xu WY, Zhu DP. The chemicalephysical combined method for improvingclay slurry in land reclamation. In: IACGE 2013. Reston, VA, USA: The AmericanSociety of Civil Engineers; 2013b. p. 308e15.

Wu DQ, Xu WY, Guo L, Tjuar R, Quek A. IES final report on creating a marine claymatrix with incineration ash (IBA) for land reclamation. Singapore: ChemilinkR&D Center; 2014. p. 107.

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Dr. Dongqing Wu born in 1959 in China, graduated fromThe East China University ofWater Resources with B.Eng. inJanuary, 1982 and then Hohai University with M.Eng. Hecompleted his PhD dissertation in geotechnical engineeringat Nanyang Technological University (NTU) in Singapore in1994. Dr. Wu is the Founder and Chief Scientist of Chem-ilink� Technologies & Products and currently the CEO ofChemilink Technologies Group, President of Chemilink R&DCentre and Executive Chairman of Chemilink NewSoil En-gineering Pte Ltd.Dr. Wu was a project engineer and then alecturer in China during 1980s, where, he received theExcellent Development Award in Science & Technologyfrom China central government and the Excellent PaperAward from Chinese Academy of Sciences. He started his

new professional career based on Singapore in 1994 and received several government-granted R&D projects for past 10 years. His technical portfolios include civil engi-neering, material science and environment engineering, and his outputs in R&D,technical and engineering aspects may be found in some 100 publications. He obtainedrich industrial experiences from conducting or involving in hundreds of civil andbuilding projects locally and internationally. His technical and engineering perfor-mances are widely reported by newspapers, magazines and TVs including “DiscoveryChannel” in its “Man Made Marvels” program (2008) for his unique innovation appliedin Singapore Changi Airport runways. Along the way towards a zero solid waste so-ciety, he is a pioneer to promote “Singapore NewSoil” brand for infrastructure con-struction, where the NewSoil is transformed from various solid wastes. He is also apioneer researcher to use “Marine Clay-Incineration Bottom Ash Matrix” for landreclamation, while he is the first to create the Chemical-Physical Combined Method toeffectively conduct land reclamation using waste materials.