Physicochemical Performance of Portland-Rice Husk Ash

Research ArticlePhysicochemical Performance of Portland-Rice HuskAsh-Calcined Clay-Dried Acetylene Lime Sludge Cement inSulphate and Chloride Media

Jackson Muthengia Wachira 1 Joseph Karanja Thiongrsquoo2 Joseph Mwiti Marangu 3

and Leonard Genson Murithi1

1Department of Physical Sciences University of Embu Embu Kenya2Department of Chemistry Kenyatta University Nairobi Kenya3Department of Physical Sciences Meru University of Science and Technology Meru Kenya

Correspondence should be addressed to Joseph Mwiti Marangu jmarangu2011gmailcom

Received 1 December 2018 Revised 12 March 2019 Accepted 17 March 2019 Published 8 April 2019

Academic Editor Robert Cerny

Copyright copy 2019 Jackson Muthengia Wachira et al is is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in anymedium provided the original work isproperly cited

is paper reports leach andor intake of SO42minus Clminus Ca2+ Na+ and K+ from andor into cement mortar cubes made from a novel

cementious material in naturally encountered environmental simulated mediae paper also reports changes in pH of the mediaover time of exposure to the cement mortar cubes e compressive strength changes of the test cement in simulated media arealso reported e novel cement labelled PCDC made from intermixing ordinary Portland cement (OPC) with waste materialswhich included rice husks waste bricks acetylene lime sludge and spent bleaching earth was previously tested and found to meetthe Kenyan Standard requirements for Portland pozzolana cement (PPC) 100mm mortar cubes were prepared and theircompressive strengths were determined after exposure to the sea water e media included sea water distilled water andsolutions of sulphates and chlorides separately for a period of six months e tests were carried alongside commercial PPC andOPC e results showed that the PCDC exhibited comparable selected ions intake andor leach to PPC in sea water sulphatesolutions and distilled water In chloride solutions the cement exhibited the highest leach in the selected ions except K+ and Na+

ionse results further showed that PCDC exhibited lower pH in all the media compared to OPC and PPCe tests showed thatthe novel cement can be used for general construction work in the tested media in a similar manner to PPC

1 Introduction

Cement is a major building binder throughout the worldOrdinary Portland cement (OPC) has been used in vastconstruction activities in the past However OPC productionrequires significant amount of energy [1] is makes theproduct unaffordable especially in low and middle economycounties In addition during the manufacturing processenormous quantities of carbon dioxide (CO2) are emitted tothe atmosphere CO2 is one of the main greenhouse gasesmainly responsible for global warming and climate change

ere is an increasing demand for greener constructionmaterials with low carbon footprint globally [2] Portland

pozzolana cement (PPC) has recently emerged as a suitablealternative to OPC PPC is mostly preferred to OPC due tothe fact that it exhibits high ultimate strength and it is moredurable than neat OPC is is mainly attributed to theinclusion of pozzolanic materials in PPC e pozzolanicmaterials are highly siliceous and aluminous and in thepresence of calcium hydroxide (CH) at ambient tempera-tures they react with silica (SiO2) and alumina (Al2O3) toform compounds processing cementitious properties [3]

Rice husk ash (RHA) and broken bricks (BBs) have beenused as pozzolanic materials for many decades [4 5] In-clusion of these materials in cement production is consid-ered an innovative solution to improve the performance of

HindawiAdvances in Materials Science and EngineeringVolume 2019 Article ID 5618743 12 pageshttpsdoiorg10115520195618743

cement-based materials and offer an environmentallyfriendly method of waste disposal However substitution ofOPC with these pozzolanic materials above 35 has beenreported to greatly lower the strength of the resultingcement-based materials [6] is has largely been attributedto insufficient CH in PPC containing pozzolanic materialsgreater than 35 percent Previous studies conducted usingPPC made from blending 55 percent of OPC with driedacetylene lime cement and an incinerated mix of rice husksreject bricks and spent bleaching earth showed that a ce-mentitious material is formed [7ndash11] ese showed that thecementitiousmaterial labelled as PCDC in this workmet theKenyan standard [12] requirements for PPC in terms ofcompressive strength and setting times [8] Further testswere therefore necessary to observe its resistivity in terms ofmain ions leach or intake in aggressive media commonlyencountered in the natural environment during the con-struction activities

2 Materials and Methods

21Materials Materials were sampled from their respectiveregions in Kenya Pozzolana material preparation and in-cineration was done in accordance with the procedureoutlined in [8] using a fixed bed kiln Sea water as obtainedfrom the sampling site was stored in clean plastic bottlesTable 1 gives the composition of various materials used inthis study

22Methods About 500ml of it was sampled for analysis ofNa+ K+ Ca2+ Clminus and SO4

2minus using the usual methods inflame photometry (for Na+ and K+) atomic absorptionspectrometry (Ca2+) potentiometry (Clminus) and turbidimetry(SO4

2minus)100mm mortar cubes were prepared using 1 3 cement

to sand ratio and a wc ratio of 046 Commercial OPC andPPC were also used alongside PCDC A vibrating pokermodel B25DS was used for compaction purposes e cubeswere demoulded after 24 hours and then cured for additional27 days in saturated calcium hydroxide solution undercomplete submersione cubes were then submerged into a500ml media in a 2 litre plastic container e media usedincluded sea water distilled water and separate solutions ofmagnesium chloride and sodium sulphate Magnesiumchloride labelled Cl1 and sulphate solutions labelled SO1were prepared to have an equivalent of chloride and sulphateconcentration in sea water respectively ese were 20000and 2342 ppm respectively Similar solutions but withdouble the chloride and sulphate Cl1 and SO2 were alsoused An aliquot of the aggressive media was sampled eachtime for analysis of the selected ions (Ca2+ Na+ Clminus andSO4minus2) An equal amount of the original solution of each

category was replenished after sampling e pH of theaggressive media was monitored by using the pH metermodel number 3405 e analysis was done for a period ofsix months

After about six months of monitoring of Ca2+ Na+ K+Clminus and SO4

2minus ions and pH changes in the corrosive media

compressive strength of the three mortar cubes represen-tative of each category was determined e change in thecompressive strength from the 28th day to the sixth monthwas calculated using the following equation

CSgain CS nth day( 1113857minusCSDW nth day( 1113857

CSDW nth day( 1113857 (1)

where CSgain is the calculated percent gain in compressivestrength CS(nth day) is the compressive strength at thenth day which in this study was 180th day andCSDW(nth day) is the compressive strength of the similarmortar cube in distilled water (which acquired a high pHwithin a short time of exposure) at the nth day

3 Results and Discussion

31 Clminus Analysis of Selected Ions from Chloride SolutionFigures 1 and 2 give the progressive intake and leaching ofthe chloride ions in magnesium chloride-simulated solu-tions against the monitoring period by mortar cubes of eachcategory

In chloride-simulated solution 1 the PCDC had thehighest initial intake followed by an early subsequent leachin chloride ions e high intake in PCDC could be asso-ciated with higher permeability due to the high levels ofsubstitution coupled with the lower pozzolanic reaction

OPC had a higher intake of the chlorides than the PPCfrom Cl1 solution is could be attributed to the higherexchange capacity due to a higher OHminus ions [11] Pozzolanareaction lowers the Ca(OH)2 content and hence the bufferstore of the OHminus ions e additional cementious materialfrom pozzolanic reaction higher Al2O3 phase from thereactive constituents of pozzolana and packaging of poz-zolana grains between cements aggregates lower the diffu-sivity of chlorides into the bulk is in turn lowers theintake of the ions in pozzolana-based cements

Table 1 Compositions of various materials used

Material Description

OPC Commercial ordinary Portland cement (425Nmm)

PPC Commercial Portland pozzolana cement orblended cement (325Nmm)

PCDC A blend of 55 OPC and 45 test ash

Test ash A blend of DALS and a calcined mix of RH SBEand ground BB

SO1 Sulphate-simulated solutions with sulphateconcentration equal to the sea water

SO2 Sulphate-simulated solutions with sulphateconcentration twice the sea water

Cl1 Chloride-simulated solutions with chlorideconcentration equal to the sea water

Cl2 Chloride-simulated solutions with chlorideconcentration twice the sea water

DALS Dried acetylene lime sludge

Corrosivemedia

Sea water 20000 and 40 000 ppm Clminus (MgCl2)solution distilled water 2342 and 4684 ppm

SO42minus (Na2SO4) solution

2 Advances in Materials Science and Engineering

As the concentration of the chloride is doubled in Cl2OPC showed a decreased intake of chlorides than the PPCPerhaps the benecial eects above of denser mortar re-duced Ca(OH)2 levels made PPC less resistant to the MgCl2attack is was attributed to higher amount of Ca(OH)2 inOPC than that in PPC High content of Ca(OH)2 in OPCmade its CSH to be attacked more by chlorides than that inPPC PPC being denser from pozzolanic reaction may haveleft little space for expansive brucite fromMg attack [13 14]

32 SO42minus Analyses in Chloride-Simulated Solutions

Figures 3 and 4 show the sulphate leach and intake from thechloride-simulated solutions Sulphates were observed toincrease in the corrosive media rapidly up to about the 11thand 25th day in the simulated chloride solution 1 and 2respectivelye ions then showed a fast decline to an almostconstant amount

e chloride solutions did not have sulphate ion in therst place and therefore the ions must have been leachedfrom the cement mortars e sulphates may have beenleached as soluble salts of sodium andor potassium or eventhe sparingly soluble calcium sulphatesese sulphates mayhave originated mainly from the interground gypsum

e decrease in the sulphates from the corrosive solutioncould have been due to the precipitation of the sulphate ionsas calcium sulphates e reaction between Ca2+ and SO4

2minus

is as shown in the following equation

Ca2+(aq) + SO42minus

(aq) + 2H2O(l)⟶ CaSO4 middot 2H2O(s) (2)

e sulphates could have also been precipitated due tothe eect of the chlorides and hydroxides on the mediaSulphates especially of alkalis and alkaline earth metalshave a diminishing solubility in the presence of chloridesand hydroxides [15]

As the concentration of the chloride solutions weredoubled the OPC showed the highest sulphate leach ismay have been attributed to a higher level of gypsum in OPCthat became a vulnerable phase as the chloride concentrationincreased e substitution of the OPC with pozzolana re-duces the amount of available sulphate from cements It wasnotable that in both cases of chloride concentrations theamount of leached sulphates from PCDC was about thesame at the early days of subjection in the corrosion media

As the monitoring period progressed it was observedthat the test-mortar cements exhibited a decline in SO4

2minus

leach e decline was most pronounced in PCDC especiallywith increased chloride concentration With timepozzolana-based cements become denser due to pozzolanicreactionsus PCDCmay have become less permeable andhence less vulnerable to the aggressive media

33 K+ Na+ Ca2+ and pH Analyses in Chloride-SimulatedSolutions Figures 5ndash7 show the results of K+ Na+ and Ca2+

050

100150200250300350400

[SO

42ndash] (

ppm

)

30 60 90 120 150 1800Monitoring period (days)

PCDC Cl2OPC Cl2PPC Cl2

Figure 4 SO42minus analyses in chloride-simulated solution 2


7500

11000

14500

18000

21500

[Clndash ] (

ppm

)


Figure 1 Clminus analyses in chloride-simulated solution 1


[Clndash ] (

ppm

)

25000280003100034000370004000043000



0

80

160

240

320

[SO

42ndash] (

ppm

)

30 60 90 120 150 1800Monitoring period



Advances in Materials Science and Engineering 3

analyses Figure 8 shows the results of pH variation ofchloride-simulated solutions over a period of six months

In the test solutions an increase in the amount of leachedCa2+ from the mortar cubes followed by a decline imme-diately around the 11th day was observed Upon continuedmonitoring of the test cement mortars it was observed that

there was a decline in the Ca2+ leached Ingress of chloridescould have improved the microstructure and hence per-meability and strength of pozzolana-based cements Poz-zolanic reactions consume Ca(OH)2 us blended mortarsas observed were expected to show a decline in the amountof leached ions for example Ca2+ as permeability decreasedbecause their resistivity to aggressive agents had increased

ere was a marked increase in pH of the chloridesolution accompanied by leaching of the alkali metal ionsfrom the test cement mortars Generally contact water withconcrete is expected to attain a pH value above 9 or almost atequilibrium with the pore water is corresponded with theleach of the alkali ions observed in all the test cements

e ingress of Clminus is accompanied by leaching (in ex-change) of OHminus from the cement pasteis introduces OHminusfrom the pore solution into the corrosive media which at-tains a pH equilibrium between the pore water and cementmortar environment is could also be achieved throughionic transfer [16] In all cements the K+ ion was highlyleached from the mortar cubes perhaps due to its higherconcentration than Na+ in the pore solution [17]

e leaching of the alkali ions continued up to a certainpoint where it almost attained a constant amount is is asimilar scenario observed by Herold [18] who analysed forCa Mg Fe Al Si Na and K in solutions where hardenedpastes of OPC with a wc ratio of 05 were immersed eauthor [18] observed that there was a marked reduction inleaching in stationary systems And this was attributed to thegrowth of residual protective layer which changed the dis-solution rate from reaction controlled to a diusion con-trolled process e worker also attributed the decline inleaching of the ions to the growth of temporary concen-tration buildup in the corrosive media which caused a de-pression of the dissolution behaviour of the paste

It was observed that the alkali metal ions were leachedmost from PPCe higher leaching of alkalis in PPCmay beattributed to the observed higher pH in the chlorides so-lutions Perhaps the microcracking associated with Mg at-tack was more severe in PPC is may have made thecement more porous and hence highly leached

e leaching of the alkali and alkali earth metal ions isdeleterious as it may lead to disintegration of the CSH eleach could also lead to loss in concrete strength lowering of

PCDC Cl1PCDC Cl2OPC Cl1

OPC Cl2PPC Cl1PPC Cl2

0

100

200

300

400

500

600

[K+ ] (

ppm

)


Figure 5 K+ analyses in chloride-simulated solution

0100200300400500600700800900

[Na+ ] (

ppm

)




Figure 6 Na+ analyses in simulated chloride solutions

0

500

1000

1500

2000

[Ca2+

] (pp

m)




Figure 7 Ca2+ analyses in simulated chloride solutions

OPC Cl1OPC Cl2PCDC Cl1

PCDC Cl2PPC Cl1PPC Cl2

65

75

85

95

105

115

pH

25 99857253 16132 39 46 131

18013106 180 3

Monitoring period (days)

Figure 8 pH measurements in simulated chloride solutions


the pore pH and hence leading to breakdown in passivity ofreinforcement It would also lead to disruption of the mediathrough which concrete phases and reactions are held PPCexhibited the highest main ion loss for maintenance of thepore pH for example Na+ an important aspect in theconcrete system

34 Sulphate Analyses in Sulphate-Simulated SolutionsFigures 9 and 10 show the analyses of sulphate ions againstthe monitoring period from the sulphate-simulated solu-tions PCDC showed a continuous intake of the ions up toabout 103rd and 163rd day for the SO1 and SO2 solutionsrespectively After these days a subsequent leach was ob-served Similar observations were made for the PPC (intakewas observed up to about the 163rd day followed byleaching) OPC exhibited an intake up to about 103rd and45th day for simulated solution 1 and 2 respectively afterwhich leaching was observed An increased intake of thesulphates was observed when the concentration of thesulphates was doubled

OPC showed an initial reduced sulphate intake at thelower sulphate-simulated solution up to about the 11th day ofmonitoring Ingress of sulphates results in formation of forexample gypsum and ettringite (3CaOmiddotAl2O3middot3CaSO4middot32H2O)[19] ese are expansive products which may have createdmicrocracks at an early time in OPC that would have pavedway for leaching of the sulphates after ingress

PCDC and PPC showed a similar intake of the sulphatesin both solutions PCDC had a higher substitution level thanPPC e pozzolanic reaction and cement hydration weretherefore expected to be slower in PCDC compared to PPCerefore its resistivity to sulphates may not only have beendue reduction in its permeability from secondary CSH fromthe pozzolanic reaction is may also have been attributedto the packaging of the pozzolana particles in between theaggregates and cement grain which reduces permeability

35 K+ Na+ and pH Analyses in Sulphate-SimulatedSolutions Figures 11ndash13 show the changes in K+ Na+and pH in the simulated sulphate solutions ere wasprogressive increase in K+ ions in the solutions e pH rosefrom the near neutral to higher than 9

It was observed that Na+ ions ingressed the cementmortar cubes initially After sometime the ions were sub-sequently leached K+ exhibited a continuous leachthroughout the experimental period e alkalis pre-dominantly maintain the high pH of pore water eleaching preferentially of K+ ions helped maintain the pHequilibrium between the mortar matrix and the surroundingenvironment e intake of the Na+ ion was mainly due tothe ion concentration gradient between the aggressive media(which was prepared from sodium sulphates salt) and thecement pore system

All the aggressive media except PCDC and OPC sul-phate solution 1 showed an increase in pH to approximately11 upon the immersion of the mortar cubes in the solutionsere was a decline in these solutionsrsquo pH after sometimebut PPCrsquos solutions maintained a higher pH to the end of the

monitoring period Some authors [20 21] observed a steadyrise in pH of the corrosive media in few days to about 12due to release of the OHminus from the pore solution of theassociated concrete e interdependence of sulphate intakeand OHminus to be related as shown in the following equation

SO42minus[ ]

t SO4

2minus[ ]ominus12OHminus[ ]t (3)

e subscripts o and t denote concentrations (in thesolution under investigation) of the bracketed ions at initialand after a given time respectively is shows that there is arise in OHminus and hence pH as the sulphates ingress into acement mortar [20]

PCDC SO1OPC SO1PPC SO1

500700900

11001300150017001900210023002500

[SO

42ndash] (

ppm

)


Figure 9 SO42minus analyses in sulphate-simulated solution 1


100015002000250030003500400045005000

[SO

42ndash] (

ppm

)



PCDC SO1PCDC SO2OPC SO1

OPC SO2PPC SO1PPC SO2

0100200300400500600

[K+ ] (

ppm

)


Figure 11 K+ analyses in sulphate-simulated solution


PCDC showed the lowest leach in K+ than the PPC andOPC as shown in Figure 10 is corresponded to the ob-served least pH as can be seen from Figure 12 is could beattributed to the high replacement of the OPC by the test-ashhence lower leacheable alkalis from the cement pore solutione lower leach of the K+ ions maintains the PCDC poresolution pH from the fact that blended cements have loweralkali content with K+ taking the larger portion of the alkalis

36 Sulphate Analyses in Distilled Water Figure 14 showsthe analyses of sulphate ions versus the monitoring period indistilled water

Leaching of the sulphates was noted in all the test ce-ments With time the amount of leached sulphates got to aconstant level is could be compared to a scenario where aprotective layer development on cement mortar and aconcentration buildup in the solution are observed [18]

PPC and PCDC exhibited a continued leaching with PPCshowing a higher leach PCDC had a higher substitutionlevel than PPC It was therefore expected as observed thatPPC would exhibit a higher sulphate leachis is because ofits initial higher amount of sulphates added as gypsum tocontrol poundash set

37 Ca2+ K+ Na+ and pH Analyses in DistilledWater Figures 15ndash18 show the analyses of Ca2+ K+ Na+and pH from distilled water versus the monitoring periode Ca2+ ions were only detectable for a few days in OPC

and PPCmedia Ca2+ levels in PCDC varied from one testingday to the other

Ca2+ either as CaO or Ca(OH)2 leaching through watercan be through its slight solubility or through attack viasolubilization of atmospheric CO2 [22] as shown in thefollowing equationH2O(l) + CO2(g) + Ca(OH)2(slightly soluble)⟶ Ca HCO3( )2(aq)

(4)



500700900

11001300150017001900210023002500

[Na+ ] (

ppm

)

30 60 90 120 150 1800


Figure 12 Na+ analyses from simulated sulphate solutions

PPC SO1PCDC SO1PPC SO2

OPC SO1OPC SO2PCDC SO2

775

885

99510

10511

115

pH

10 20 30 40 50 60 70 80 90 110

160

1500

140

180

130

100

170

120


Figure 13 pH measurements in simulated sulphate solutions

PCDC DWOPC DWPPC DW

0

20

40

60

80

[SO

42ndash] (

ppm

)


Figure 14 SO42minus analyses in distilled water

PCDC DWPPC DWOPC DW

0

05

1

15

2

25

3

35

[Ca2+

] (pp

m)

50 100 1500Monitoring period (days)

Figure 15 Ca2+ analyses in simulated distilled water

PCDC DWOPC DWPPC DW

050

100150200250300

[K+ ] (

ppm

)


Figure 16 K+ analyses in simulated distilled water


e leaching of Ca2+ from OPC and PPC declinedimmediately after the rst few days e lower Ca2+ leachcould probably be explained from a pH point of view Asdiscussed earlier the solubility of Ca2+ decreases with in-crease in pH thus higher leach in K+ and Na+ fromOPC andPPC would have inhibited the leach of Ca2+ from the poresolution of the hydrated cement matrix

As observed in other experimental results above Na+and K+ were least leached from PCDC e lower leach ofthese alkalis from the PCDC could explain the lower pHobserved of the PCDC cementrsquos aggressive media as com-pared to OPC and PPC PPC exhibited the highest leach ofthe alkalis combined and correspondingly the highest pH inits aggressive media was observed

Distilled water was not as deleterious as had been ob-served of the chlorides and sulphates especially in theleaching of the main cement constituents for example Ca2+Na+ and K+ among otherse leach of these constituents indistilled water could have mainly been due to concentrationdierence between the cement matrix and corrosive envi-ronment as opposed to chemical attack More so with timehydration of the cement mortar progresses thus making themortar less permeable and hence less vulnerable to attack

38 Chloride Analyses in Sea Water Figure 19 shows theanalyses of chlorides against monitoring period in sea water

It was observed that the test cements showed an intake ofClminus that was continued up to the 103th day After this the testsamples showed an increase in the chloride content in the

corrosive media e leaching could be attributed to thesaturation of the chlorides in the mortar cubes Someworkers [23] attributed the decline in Ca(OH)2 due topozzolanic reaction to increase in solubility of the chlor-oaluminateis may lead to the formation of soluble salts ofthe chlorides of calcium aluminium and iron from de-composition of the same [24] e salts may leach from theconcrete mass A similar trend of intake and subsequentleaching was observed in [25]e author [25] attributed thisto the saturation of the chlorides in the mortar

PPC showed the lowest intake of Clminus PPC is known tocure over a long time compared to OPC It is well docu-mented that a majority of blended cements show a greaterresistance to aggressive media [13 26ndash29] such as sea waterIt was therefore expected as observed that PPC would showgreater resistance to ingress in the constituents of the seawater

e high intake of chlorides by PCDC could be attrib-uted to its high level of substitution is could be attributedto a lower hydration rate of cementus the cement showeda higher permeability than OPC and PPC

39 Sulphates Analyses in Sea Water Figure 20 shows theresults of analyses of sulphates in sea water media against themonitoring period OPC showed the highest intake of thesulphates after which the cement mortar showed leaching ofthe same evidenced by increase in the sulphates in its ag-gressive media

All the cement mortars showed intake of sulphates OPCshowed an intake up to about the 45th day after which itshowed subsequent leaching OPC is known to be easilyattacked by sulphates [30ndash33] In sulphate-simulated solu-tions OPC showed higher intake especially at higher con-centrations of the sulphate solutions (Figure 10) It wasobserved that at the higher sulphate concentration the OPCexhibited leach after intake of the sulphates In simulatedchloride solution OPC showed the highest leach in thesulphates especially at the higher chloride concentration(Figure 4) It would then appear that the combined eect of

050

100150200250300350400450

[Na+ ] (

ppm

)


PCDC DWOPC DWPPC DW

Figure 17 Na+ analyses in simulated distilled water

775

885

99510

pH


PCDC DWOPC DWPPC DW

Figure 18 pH measurements in simulated distilled water

7500

10500

13500

16500

19500

22500

[Clndash ] (

ppm

)


PCDC SWOPC SWPPC SW

Figure 19 Clminus analyses in sea water


the two ions (sulphates and chlorides in sea water) exhibitedthe same trend where they were more aggressive to OPCthan the blended cements But the severity of attack in theseparate aggressive solutions was noted to be higher com-pared to sea water

ere was no signicant dierence between PCDC andPPC in terms of sulphate intake in sea water is wasdespite the high intake of chlorides by PCDC from the samesolutionis could be accounted for the pozzolana includedwhich makes them less permeable to aggressive agents orintake of chlorides suppressing the intake of the sulphates

310 Ca2+ K+ Na+ and pH Analyses in SeaWater Figures 21ndash24 show the results for analyses of Ca2+K+ Na+ and pH in sea water against the monitoring period

e cements were observed to leach K+ with the highestleach observed from PPC ere was an initial intake of Na+

and then a subsequent leach is is a similar trend asobserved in the above experimental resultse high leach ofthe K+ ion corresponded to the observed pH in the ag-gressive media PPC aggressive media exhibited the highestpH

PPC had the highest intake of Na+ followed by PCDCand least OPC especially toward the end of the monitoringperiod e intake of Na+ may have been to counter for theleached K+ on an ion exchange point of view

e corrosive media was shown to exhibit a decline inCa2+ ions a similar scenario to the chloride-simulated so-lutions PCDCmaintained a higher amount of the ions in itscorrosion media Ca2+ ion solubility decreases with theincrease in pH us the observed least pH in PCDC mediafavoured a higher concentration of the same as opposed toPPC which exhibited the highest pH with least Ca2+ con-centrations in its aggressive solution

e corrosion media was observed to have attained a pHgreater than 9 A rise in pH from about 752 to 917 in seawater into which concrete was immersed in a monthrsquos time

had been observed elsewhere [34] is has been attributedto Ca(OH)2 leach from the concrete Oxides of potassiumand sodium have also been found to be leached fromconcrete immersed in sea water simulated sea water and tapwater [27]

311 Compressive Strength Changes in Mortars

3111 Compressive Strength Changes in Mortars Immersedin Chloride Solution Figure 25 represents the percent gainand loss in compressive strength of cement in simulatedmagnesium chloride solutions

1000

1400

1800

2200

2600

[SO

42ndash] (

ppm

)


PCDC SWOPC SWPPC SW

Figure 20 SO42minus analyses in sea water

300400500600700800900

1000

0 30 60 90 120 150 180Monitoring period (days)

[K+ ] (

ppm

)

PCDC SWOPC SWPPC SW

Figure 21 K+ analyses in sea water

9900

10200

10500

10800

0 30 60 90 120 150 180

[Na+ ] (

ppm

)


PCDC SWOPC SWPPC SW

Figure 22 Na+ analyses in sea water

200

250

300

350

400

450

0 30 60 90 120 150 180

[Ca2+

] (pp

m)


PCDC SWOPC SWPPC SW

Figure 23 Ca2+ analyses in sea water


ere was an observed increase in strength for the testcements immersed in Clminus-simulated solution but it de-creased when the Clminus concentration was doubled in PPC andPCDC (TCal minus1503 and minus750 respectively) PPC had thehighest strength gain in simulated solution 1 is can beattributed this to ingress of the chloride ions Chlorides areactive in enhancing the strength gain because of both theirsmall charge and ionic sizes which enhances its diffusivityChloride ions activate pozzolanic reactions and initiateresidual cement hydration [6] thus increasing their strength

ere was a marked decrease in compressive strengthwhen chloride concentration was doubled is could beattributed to the formation of brucite [Mg(OH)2] as a result ofincreased ingress of MgCl2 on mortar which introduces bothchlorides and Mg ions Brucite [Mg(OH)2] is formed via themagnesium ion attack as shown in the following equation

Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)

Brucite is an expansive product and can lead to crackingand hence lowering cement strength Pozzolanic reactionmakes blended cements denser is leaves little space forthe expansive brucite in case of Mg attack on the mortar

is exaggerates the damage due to Mg-attack in thepozzolana-based cements is may have explained whyalthough at the lower chloride concentration PPC had thehighest strength gain and it showed a decline in simulatedchloride 2 solutione results thus suggested that at higherchloride concentration the medium was more aggressiveand hence an earlier Mg attack

Pozzolanic reaction leaves limited Ca(OH)2 for the Mgattack e reduced Ca(OH)2 leaves the CSH as the im-mediate culprits e result is the formation of non-cementious MSH e attack was not severe in PCDCcompared to PPCe less severity could be attributed to thelevel of substitution us the pozzolanic-Ca(OH)2 reactionwas not expected to have consumed all Ca(OH)2 or made themortar as dense as PPC More so it would seem that theintroduced Ca(OH)2 as DALS may have offered a phase forMg attack prior to silica

3112 Compressive Strength Changes in Mortars Immersedin Sulphate Solution e percent gain in the compressivestrength of mortar cubes immersed in sodium sulphate-simulated solutions was also determined after about sixmonths of subjecting the mortar cubes to the corrosiveagents e results are presented in Figure 26

PCDC and PPCmortar cubes under this corrosive mediaregistered a significant gain in compressive strength egain was even more pronounced with increase in sulphateconcentration (TCal 449 for PCDC SO2 versus PCDC SO1TCal 1840 for PPC SO2 versus PPC SO1 way above TCritvalue of 430) e strength gain in OPC was also notable inthe sulphate solution but there was a significant decline ingain when the solution concentration was doubled(TCal minus559 for OPC SO2 versus OPC SO1 the negativesign indicating a decline in strength gain) Sulphates havetwo effects on hydrated cements first they raise the pH ofpore water in cement matrix owing to ion exchange asshown in the following ionic equation [7]

SO2minus4 (aq) + Ca(OH)2(s) + 2H2O(l)

⟶ CaSO4 middot 2H2O(s) + 2OHminus(6)

is increases the concentration of OHminus in the porewater hence increasing the pH of cement mortar matrix ehigh pH results in increased dissolution of pozzolanicmaterials in PPC and PCDC hence promoting the pozzo-lanic reaction Enhanced pozzolanic reaction subsequentlyincreases the early compressive strength of cement mortarsdue to increased formation of CSH that is responsible forstrength [8 9] Secondly sulphates react with aluminiumoxide in the glass phase of pozzolanic materials to formettrigite (AFt phase) Ettrigite formed at early ages of curingresults in a significant densification hence forming a lessporous structure and subsequently leads to higher strength[6] Increase in compressive strength of OPC can be at-tributed to the presence of Na+ which promotes the hy-dration residual cement phases OPC is the most susceptibleto the deleterious effects of sulphates e two effects tend togive an increase and then a decline in physical propertiessuch as strength in mortars or concrete

775

885

99510

10511

0 30 60 90 120 150 180

pH

Monotoring period (days)

PCDC SWPPC SWOPC SW

Figure 24 pH measurements in sea water

ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2

Figure 25 Percent gain in compressive strength versus test cementin chloride solutions


PCDC registered a lower strength gain than PPC Asobserved from even the 28th day compressive strength insaturated calcium hydroxide solution PCDC had the leastcompressive strength development is perhaps could bedue to the high substitution level coupled with slow de-velopment of strength from pozzolanic reaction AlthoughSO4

2minus and Na+ may have activated pozzolanic reaction thereaction is still slower compared to the PPCrsquos High levels ofsubstitution of OPC have been observed elsewhere to havelow-strength gain

e lower strength in OPC as the sulphate concentrationwas doubled could be inferred from the three stages ofsulphate attack classified as early attack transition and laterstages At the early stage densification of mortar or concretedue to sulphate products increased strength but in transi-tion and later stages the deleterious effects of the sulphateswere observed e deleterious effects brought about declinein physical properties such as the compressive strength Anincrease in sulphate concentration in this study may havecaused an earlier lapse of the early stages compared to thelower sulphate concentration is may be attributed to theobserved decline in strength gain as the sulphate concen-tration was increased

In general the PPC had the highest strength gain fol-lowed by PCDC in the sulphate solutionsis is expected ofblended cements compared to OPC is is mainly attrib-uted to low permeability from the resultant secondary CSHfrom pozzolanic reactione packaging of pozzolana grainsbetween the cement grains and aggregates also reducepermeability e reduction in Ca(OH)2 content throughpozzolanic reaction reduces a phase that is most vulnerableto sulphate attackese factors make blended cements to beless vulnerable to the sulphate form of attack

3113 Compressive Strength Changes in Mortars Immersedin Distilled Water e change in the compressive strengthof the cement mortars subjected to distilled water for sixmonths was compared to their respective strength of the28 days of curing in saturated calcium hydroxide solutionFigure 27 shows these results

ere was observed strength gain for all the test cementsin watere increase in the compressive strength in distilledwater could mainly be attributed to a continued hydration ofthe cement without activators for example Na+ Clminus andSO4

2minus as experienced in other aggressive solution e waterdid not contain these activators that initiate residue cementhydration or pozzolanic reaction and thus strength devel-opment increase as observed was expected to be low

PCDC had the highest strength gain which is signifi-cantly higher than OPC (TCal 517 against TCrit 430)ere was no significant difference in strength gain betweenPCDC and PPC (TCal 217) Pozzolana-based cement hasslow development in strength as compared to OPC if ag-gressive ions are not encountered is is attributed to lowerpozzolanic reaction With time due to continued pozzolanicreaction blended cements are expected to exhibit highergain in compressive strength than OPC as observed in thiscase

3114 Compressive Strength Changes in Mortars Immersedin Sea Water Figure 28 shows the percent gain in com-pressive strength versus test cement in sea water

PPC had significant higher strength gain than OPC andPCDC in sea water (TCal 714 for PPC against OPC 985 forPPC against PCDC and 403 for OPC against PCDC[TCrit 430]) is could be attributed to the activation ofpozzolanic reaction and rehydration of residual cements dueto ingress of the sulphate chloride and sodium ions isimproves the compressive strength of the resultant mortarIn sea water deleterious products for example magnesiumsilicate hydrates calcium sulphates and ettringite areformed Brucite [Mg(OH)2] an expansive product isformed via the magnesium ion attack as shown in the fol-lowing equation

Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)

e buildup process of the magnesium and sodium saltsfor example sulphates through hydration dehydration andfinally rehydration is another expansive process that isdeleterious and likely in sea water are shown in the followingequations

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50

Figure 26 Percent gain in compressive strength versus test cement

54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement

Figure 27 Percent gain in the compressive strength versus testcement in distilled water


Na2SO4 + 10H2OharrNa2SO4 middot 10H2O

MgSO4 + H2OharrMgSO4 middot H2O harr5H2OMgSO4

middot 6H2OharrH2OMgSO4 middot 7H2O

(8)

A combination of the above products would be expectedto exhibit higher deleterious effects by sea water compared toseparate aggressive media of sulphates and chlorides ecomparatively low percent gain in strength for PCDC couldbe attributed to the high substitution level

4 Conclusion

From this study the following conclusions were made

(i) Despite the leaching andor intake of the selectedions analysed in this study PPC and PCDCexhibited comparative results suggesting thatPCDC could be used in similar manner to PPC ingeneral construction

(ii) Increased concentration of sulphate ions in thepresence of magnesium ions resulted in decreasedcompressive strength

Data Availability

e data used in the manuscript will be provided uponrequest

Conflicts of Interest

e authors declare that there are no conflicts of interest inthis paper

Acknowledgments

e authors wish to acknowledge the financial supportgranted by the Kenyatta University that facilitated this work

References

[1] P J Jackson and P C Hewlett ldquo2mdashportland cement clas-sification andmanufacturerdquo in Learsquos Chemistry of Cement and

Concrete pp 25ndash94 Butterworth-Heinemann Oxford UK4th edition 1998

[2] S Noor-ul-Amin ldquoUse of clay as a cement replacement inmortar and its chemical activation to reduce the cost andemission of greenhouse gasesrdquo Construction and BuildingMaterials vol 34 pp 381ndash384 2012

[3] M J Mwiti T J Karanja andW J Muthengia ldquoProperties ofactivated blended cement containing high content of calcinedclayrdquo Heliyon vol 4 no 8 article e00742 2018

[4] P Chindaprasirt S Rukzon and V Sirivivatnanon ldquoRe-sistance to chloride penetration of blended Portland cementmortar containing palm oil fuel ash rice husk ash and fly ashrdquoConstruction and Building Materials vol 22 no 5 pp 932ndash938 2008

[5] M J Washira M G Kanyago and T O J KaranjaldquoCementing material from rice husk-broken bricks-spentbleaching earth-dried calcium carbide residuerdquo Mediterra-nean Journal of Chemistry vol 2 no 2 pp 401ndash407 2012

[6] J M Marangu J K iongrsquoo and J M Wachira ldquoChlorideingress in chemically activated calcined clay-based cementrdquoJournal of Chemistry vol 2018 Article ID 1595230 8 pages2018

[7] C Shi and R L Day ldquoChemical activation of blended cementsmade with lime and natural pozzolansrdquo Cement and ConcreteResearch vol 23 no 6 pp 1389ndash1396 1993

[8] C Shi and R L Day ldquoAcceleration of the reactivity of fly ashby chemical activationrdquo Cement and Concrete Researchvol 25 no 1 pp 15ndash21 1995

[9] F Sajedi andH A Razak ldquoe effect of chemical activators onearly strength of ordinary Portland cement-slag mortarsrdquoConstruction and Building Materials vol 24 no 10pp 1944ndash1951 2010

[10] G J Ochungrsquoo 7e Production of Rice Husk Ash BasedCementious Materials Kenyatta University Nairobi Kenya1993

[11] O E Gjoslashrv and Oslash Vennesland ldquoDiffusion of chloride ionsfrom seawater into concreterdquo Cement and Concrete Researchvol 9 no 2 pp 229ndash238 1979

[12] Kenya Bureau of Standards Kenya Standard Specification forPortland Pozzolana Cements KS 1775 Part 5 Kenya Bureau ofStandards Nairobi Kenya 1993

[13] O S B Al-Amoudi ldquoAttack on plain and blended cementsexposed to aggressive sulfate environmentsrdquo Cement andConcrete Composites vol 24 no 3-4 pp 305ndash316 2002

[14] W Kurdowski ldquoe protective layer and decalcification ofC-S-H in the mechanism of chloride corrosion of cementpasterdquo Cement and Concrete Research vol 34 no 9pp 1555ndash1559 2004

[15] A Seidell and W F Linke Solubilities of Inorganic and Or-ganic Compounds D Van Nostrand Company New YorkNY USA 3rd edition 1952

[16] F Adenot and M Buil ldquoModelling of the corrosion of thecement paste by deionized waterrdquo Cement and ConcreteResearch vol 22 no 2-3 pp 489ndash496 1992

[17] S Diamond ldquoLong-term status of calcium hydroxide satu-ration of pore solutions in hardened cementsrdquo Cement andConcrete Research vol 5 no 6 pp 607ndash616 1975

[18] G Herold ldquoCorrosion of cementious materials in acid wa-tersrdquo in Mechanisms of Chemical Degradation of Cement-Based Systems K L Scrivener and J F Young Edspp 98ndash105 E amp FN Spon An Imprint of Chapman and HallBoston USA 1995

[19] W G Hime and BMather ldquoldquoSulfate attackrdquo or is itrdquoCementand Concrete Research vol 29 no 5 pp 789ndash791 1999

0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement

Figure 28 Percent gain in compressive strength versus test cementin sea water


[20] P W Brown ldquoAn evaluation of the sulfate resistance ofcements in a controlled environmentrdquo Cement and ConcreteResearch vol 11 no 5-6 pp 719ndash727 1981

[21] C F Ferraris J R Clifton P E Stutzman and E J GarboczildquoMechanisms of degradation of Portland cement-based sys-tems by sulphate attackrdquo in Mechanisms of Chemical Deg-radation of Cement-Based Systems K L Scrivener andJ F Young Eds pp 185ndash192 E amp FN Spon An Imprint ofChapman and Hall Boston MA USA 1995

[22] H F W Taylor Cement Chemistry Taylor and omasTelford Services Ltd London UK 1997

[23] C Arya N R Buenfeld and J B Newman ldquoFactors influ-encing chloride-binding in concreterdquo Cement and ConcreteResearch vol 20 no 2 pp 291ndash300 1990

[24] A Rasheeduzzafar S E Hussain and A S Al-Gahtani ldquoPoresolution composition and reinforcement corrosion charac-teristics of microsilica blended cement concreterdquo Cement andConcrete Research vol 21 no 6 pp 1035ndash1048 1991

[25] J K iongrsquoo7e Effects of Ions on Mortar Cubes Made withKenyan Cements and Sands University of Nairobi NairobiKenya 1987

[26] A Cheng R Huang J Wu and C Chen ldquoInfluence of GGBSon durability and corrosion behavior of reinforced concreterdquoMaterials Chemistry and Physics vol 93 no 2-3 pp 404ndash4112005

[27] E Ganjian and H S Pouya ldquoEffect of magnesium and sulfateions on durability of silica fume blended mixes exposed to theseawater tidal zonerdquo Cement and Concrete Research vol 35no 7 pp 1332ndash1343 2005

[28] K M A Hossain and M Lachemi ldquoCorrosion resistance andchloride diffusivity of volcanic ash blended cement mortarrdquoCement and Concrete Research vol 34 no 4 pp 695ndash7022004

[29] M D A omas and J D Matthews ldquoPerformance of pfaconcrete in a marine environmentmdash10-year resultsrdquo Cementand Concrete Composites vol 26 no 1 pp 5ndash20 2004

[30] O S B Al-Amoudi and M Maslehuddin ldquoe effect ofchloride and sulphate ions on reinforcement corrosionrdquoCement and Concrete Research vol 23 no 1 pp 139ndash1461993

[31] M Mather ldquoField and laboratory studies of the sulphateresistance of concreterdquo in Performance of ConcreteE G Swenson Ed pp 66ndash76 University of Toronto PressToronto Canada 1968

[32] H F W Taylor ldquoDiscussion sulfate attack mechanismsrdquoMaterials Science of Concrete vol 33-34 1999

[33] J Zuquan S Wei Z Yunsheng J Jinyang and L JianzhongldquoInteraction between of sulfate and chloride solution attack ofconcretes with and without fly ashrdquo Cement and ConcreteResearch vol 37 no 8 pp 1223ndash1232 2007

[34] H Yigiter H Yazıcı and S Aydın ldquoEffects of cement typewatercement ratio and cement content on sea water re-sistance of concreterdquo Building and Environment vol 42 no 4pp 1770ndash1776 2007


CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018


Journal of

Chemistry

Analytical ChemistryInternational Journal of


ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of



Advances in Condensed Matter Physics


International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of


NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of


High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in



ChemistryAdvances in


Advances inPhysical Chemistry


BioMed Research InternationalMaterials

Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

cement-based materials and offer an environmentallyfriendly method of waste disposal However substitution ofOPC with these pozzolanic materials above 35 has beenreported to greatly lower the strength of the resultingcement-based materials [6] is has largely been attributedto insufficient CH in PPC containing pozzolanic materialsgreater than 35 percent Previous studies conducted usingPPC made from blending 55 percent of OPC with driedacetylene lime cement and an incinerated mix of rice husksreject bricks and spent bleaching earth showed that a ce-mentitious material is formed [7ndash11] ese showed that thecementitiousmaterial labelled as PCDC in this workmet theKenyan standard [12] requirements for PPC in terms ofcompressive strength and setting times [8] Further testswere therefore necessary to observe its resistivity in terms ofmain ions leach or intake in aggressive media commonlyencountered in the natural environment during the con-struction activities

2 Materials and Methods

21Materials Materials were sampled from their respectiveregions in Kenya Pozzolana material preparation and in-cineration was done in accordance with the procedureoutlined in [8] using a fixed bed kiln Sea water as obtainedfrom the sampling site was stored in clean plastic bottlesTable 1 gives the composition of various materials used inthis study

22Methods About 500ml of it was sampled for analysis ofNa+ K+ Ca2+ Clminus and SO4

2minus using the usual methods inflame photometry (for Na+ and K+) atomic absorptionspectrometry (Ca2+) potentiometry (Clminus) and turbidimetry(SO4

2minus)100mm mortar cubes were prepared using 1 3 cement

to sand ratio and a wc ratio of 046 Commercial OPC andPPC were also used alongside PCDC A vibrating pokermodel B25DS was used for compaction purposes e cubeswere demoulded after 24 hours and then cured for additional27 days in saturated calcium hydroxide solution undercomplete submersione cubes were then submerged into a500ml media in a 2 litre plastic container e media usedincluded sea water distilled water and separate solutions ofmagnesium chloride and sodium sulphate Magnesiumchloride labelled Cl1 and sulphate solutions labelled SO1were prepared to have an equivalent of chloride and sulphateconcentration in sea water respectively ese were 20000and 2342 ppm respectively Similar solutions but withdouble the chloride and sulphate Cl1 and SO2 were alsoused An aliquot of the aggressive media was sampled eachtime for analysis of the selected ions (Ca2+ Na+ Clminus andSO4minus2) An equal amount of the original solution of each

category was replenished after sampling e pH of theaggressive media was monitored by using the pH metermodel number 3405 e analysis was done for a period ofsix months

After about six months of monitoring of Ca2+ Na+ K+Clminus and SO4

2minus ions and pH changes in the corrosive media

compressive strength of the three mortar cubes represen-tative of each category was determined e change in thecompressive strength from the 28th day to the sixth monthwas calculated using the following equation

CSgain CS nth day( 1113857minusCSDW nth day( 1113857

CSDW nth day( 1113857 (1)

where CSgain is the calculated percent gain in compressivestrength CS(nth day) is the compressive strength at thenth day which in this study was 180th day andCSDW(nth day) is the compressive strength of the similarmortar cube in distilled water (which acquired a high pHwithin a short time of exposure) at the nth day

3 Results and Discussion

31 Clminus Analysis of Selected Ions from Chloride SolutionFigures 1 and 2 give the progressive intake and leaching ofthe chloride ions in magnesium chloride-simulated solu-tions against the monitoring period by mortar cubes of eachcategory

In chloride-simulated solution 1 the PCDC had thehighest initial intake followed by an early subsequent leachin chloride ions e high intake in PCDC could be asso-ciated with higher permeability due to the high levels ofsubstitution coupled with the lower pozzolanic reaction

OPC had a higher intake of the chlorides than the PPCfrom Cl1 solution is could be attributed to the higherexchange capacity due to a higher OHminus ions [11] Pozzolanareaction lowers the Ca(OH)2 content and hence the bufferstore of the OHminus ions e additional cementious materialfrom pozzolanic reaction higher Al2O3 phase from thereactive constituents of pozzolana and packaging of poz-zolana grains between cements aggregates lower the diffu-sivity of chlorides into the bulk is in turn lowers theintake of the ions in pozzolana-based cements

Table 1 Compositions of various materials used

Material Description

OPC Commercial ordinary Portland cement (425Nmm)

PPC Commercial Portland pozzolana cement orblended cement (325Nmm)

PCDC A blend of 55 OPC and 45 test ash

Test ash A blend of DALS and a calcined mix of RH SBEand ground BB

SO1 Sulphate-simulated solutions with sulphateconcentration equal to the sea water

SO2 Sulphate-simulated solutions with sulphateconcentration twice the sea water

Cl1 Chloride-simulated solutions with chlorideconcentration equal to the sea water

Cl2 Chloride-simulated solutions with chlorideconcentration twice the sea water

DALS Dried acetylene lime sludge

Corrosivemedia

Sea water 20000 and 40 000 ppm Clminus (MgCl2)solution distilled water 2342 and 4684 ppm

SO42minus (Na2SO4) solution







2minus







2minus



050

100150200250300350400

[SO

42ndash] (

ppm

)





7500

11000

14500

18000

21500

[Clndash ] (

ppm

)




[Clndash ] (

ppm

)

25000280003100034000370004000043000



0

80

160

240

320

[SO

42ndash] (

ppm

)















0

100

200

300

400

500

600

[K+ ] (

ppm

)



0100200300400500600700800900

[Na+ ] (

ppm

)





0

500

1000

1500

2000

[Ca2+

] (pp

m)







65

75

85

95

105

115

pH

25 99857253 16132 39 46 131

18013106 180 3












SO42minus[ ]

t SO4




500700900

11001300150017001900210023002500

[SO

42ndash] (

ppm

)




100015002000250030003500400045005000

[SO

42ndash] (

ppm

)





0100200300400500600

[K+ ] (

ppm

)











(4)



500700900

11001300150017001900210023002500

[Na+ ] (

ppm

)

30 60 90 120 150 1800





775

885

99510

10511

115

pH

10 20 30 40 50 60 70 80 90 110

160

1500

140

180

130

100

170

120



PCDC DWOPC DWPPC DW

0

20

40

60

80

[SO

42ndash] (

ppm

)



PCDC DWPPC DWOPC DW

0

05

1

15

2

25

3

35

[Ca2+

] (pp

m)



PCDC DWOPC DWPPC DW

050

100150200250300

[K+ ] (

ppm

)














050

100150200250300350400450

[Na+ ] (

ppm

)


PCDC DWOPC DWPPC DW


775

885

99510

pH


PCDC DWOPC DWPPC DW


7500

10500

13500

16500

19500

22500

[Clndash ] (

ppm

)


PCDC SWOPC SWPPC SW














1000

1400

1800

2200

2600

[SO

42ndash] (

ppm

)


PCDC SWOPC SWPPC SW


300400500600700800900

1000


[K+ ] (

ppm

)

PCDC SWOPC SWPPC SW


9900

10200

10500

10800

0 30 60 90 120 150 180

[Na+ ] (

ppm

)


PCDC SWOPC SWPPC SW


200

250

300

350

400

450

0 30 60 90 120 150 180

[Ca2+

] (pp

m)


PCDC SWOPC SWPPC SW





Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)









775

885

99510

10511

0 30 60 90 120 150 180

pH


PCDC SWPPC SWOPC SW


ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2













Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls









2minus







2minus



050

100150200250300350400

[SO

42ndash] (

ppm

)





7500

11000

14500

18000

21500

[Clndash ] (

ppm

)




[Clndash ] (

ppm

)

25000280003100034000370004000043000



0

80

160

240

320

[SO

42ndash] (

ppm

)















0

100

200

300

400

500

600

[K+ ] (

ppm

)



0100200300400500600700800900

[Na+ ] (

ppm

)





0

500

1000

1500

2000

[Ca2+

] (pp

m)







65

75

85

95

105

115

pH

25 99857253 16132 39 46 131

18013106 180 3












SO42minus[ ]

t SO4




500700900

11001300150017001900210023002500

[SO

42ndash] (

ppm

)




100015002000250030003500400045005000

[SO

42ndash] (

ppm

)





0100200300400500600

[K+ ] (

ppm

)











(4)



500700900

11001300150017001900210023002500

[Na+ ] (

ppm

)

30 60 90 120 150 1800





775

885

99510

10511

115

pH

10 20 30 40 50 60 70 80 90 110

160

1500

140

180

130

100

170

120



PCDC DWOPC DWPPC DW

0

20

40

60

80

[SO

42ndash] (

ppm

)



PCDC DWPPC DWOPC DW

0

05

1

15

2

25

3

35

[Ca2+

] (pp

m)



PCDC DWOPC DWPPC DW

050

100150200250300

[K+ ] (

ppm

)














050

100150200250300350400450

[Na+ ] (

ppm

)


PCDC DWOPC DWPPC DW


775

885

99510

pH


PCDC DWOPC DWPPC DW


7500

10500

13500

16500

19500

22500

[Clndash ] (

ppm

)


PCDC SWOPC SWPPC SW














1000

1400

1800

2200

2600

[SO

42ndash] (

ppm

)


PCDC SWOPC SWPPC SW


300400500600700800900

1000


[K+ ] (

ppm

)

PCDC SWOPC SWPPC SW


9900

10200

10500

10800

0 30 60 90 120 150 180

[Na+ ] (

ppm

)


PCDC SWOPC SWPPC SW


200

250

300

350

400

450

0 30 60 90 120 150 180

[Ca2+

] (pp

m)


PCDC SWOPC SWPPC SW





Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)









775

885

99510

10511

0 30 60 90 120 150 180

pH


PCDC SWPPC SWOPC SW


ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2













Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls














0

100

200

300

400

500

600

[K+ ] (

ppm

)



0100200300400500600700800900

[Na+ ] (

ppm

)





0

500

1000

1500

2000

[Ca2+

] (pp

m)







65

75

85

95

105

115

pH

25 99857253 16132 39 46 131

18013106 180 3












SO42minus[ ]

t SO4




500700900

11001300150017001900210023002500

[SO

42ndash] (

ppm

)




100015002000250030003500400045005000

[SO

42ndash] (

ppm

)





0100200300400500600

[K+ ] (

ppm

)











(4)



500700900

11001300150017001900210023002500

[Na+ ] (

ppm

)

30 60 90 120 150 1800





775

885

99510

10511

115

pH

10 20 30 40 50 60 70 80 90 110

160

1500

140

180

130

100

170

120



PCDC DWOPC DWPPC DW

0

20

40

60

80

[SO

42ndash] (

ppm

)



PCDC DWPPC DWOPC DW

0

05

1

15

2

25

3

35

[Ca2+

] (pp

m)



PCDC DWOPC DWPPC DW

050

100150200250300

[K+ ] (

ppm

)














050

100150200250300350400450

[Na+ ] (

ppm

)


PCDC DWOPC DWPPC DW


775

885

99510

pH


PCDC DWOPC DWPPC DW


7500

10500

13500

16500

19500

22500

[Clndash ] (

ppm

)


PCDC SWOPC SWPPC SW














1000

1400

1800

2200

2600

[SO

42ndash] (

ppm

)


PCDC SWOPC SWPPC SW


300400500600700800900

1000


[K+ ] (

ppm

)

PCDC SWOPC SWPPC SW


9900

10200

10500

10800

0 30 60 90 120 150 180

[Na+ ] (

ppm

)


PCDC SWOPC SWPPC SW


200

250

300

350

400

450

0 30 60 90 120 150 180

[Ca2+

] (pp

m)


PCDC SWOPC SWPPC SW





Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)









775

885

99510

10511

0 30 60 90 120 150 180

pH


PCDC SWPPC SWOPC SW


ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2













Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls












SO42minus[ ]

t SO4




500700900

11001300150017001900210023002500

[SO

42ndash] (

ppm

)




100015002000250030003500400045005000

[SO

42ndash] (

ppm

)





0100200300400500600

[K+ ] (

ppm

)











(4)



500700900

11001300150017001900210023002500

[Na+ ] (

ppm

)

30 60 90 120 150 1800





775

885

99510

10511

115

pH

10 20 30 40 50 60 70 80 90 110

160

1500

140

180

130

100

170

120



PCDC DWOPC DWPPC DW

0

20

40

60

80

[SO

42ndash] (

ppm

)



PCDC DWPPC DWOPC DW

0

05

1

15

2

25

3

35

[Ca2+

] (pp

m)



PCDC DWOPC DWPPC DW

050

100150200250300

[K+ ] (

ppm

)














050

100150200250300350400450

[Na+ ] (

ppm

)


PCDC DWOPC DWPPC DW


775

885

99510

pH


PCDC DWOPC DWPPC DW


7500

10500

13500

16500

19500

22500

[Clndash ] (

ppm

)


PCDC SWOPC SWPPC SW














1000

1400

1800

2200

2600

[SO

42ndash] (

ppm

)


PCDC SWOPC SWPPC SW


300400500600700800900

1000


[K+ ] (

ppm

)

PCDC SWOPC SWPPC SW


9900

10200

10500

10800

0 30 60 90 120 150 180

[Na+ ] (

ppm

)


PCDC SWOPC SWPPC SW


200

250

300

350

400

450

0 30 60 90 120 150 180

[Ca2+

] (pp

m)


PCDC SWOPC SWPPC SW





Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)









775

885

99510

10511

0 30 60 90 120 150 180

pH


PCDC SWPPC SWOPC SW


ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2













Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls











(4)



500700900

11001300150017001900210023002500

[Na+ ] (

ppm

)

30 60 90 120 150 1800





775

885

99510

10511

115

pH

10 20 30 40 50 60 70 80 90 110

160

1500

140

180

130

100

170

120



PCDC DWOPC DWPPC DW

0

20

40

60

80

[SO

42ndash] (

ppm

)



PCDC DWPPC DWOPC DW

0

05

1

15

2

25

3

35

[Ca2+

] (pp

m)



PCDC DWOPC DWPPC DW

050

100150200250300

[K+ ] (

ppm

)














050

100150200250300350400450

[Na+ ] (

ppm

)


PCDC DWOPC DWPPC DW


775

885

99510

pH


PCDC DWOPC DWPPC DW


7500

10500

13500

16500

19500

22500

[Clndash ] (

ppm

)


PCDC SWOPC SWPPC SW














1000

1400

1800

2200

2600

[SO

42ndash] (

ppm

)


PCDC SWOPC SWPPC SW


300400500600700800900

1000


[K+ ] (

ppm

)

PCDC SWOPC SWPPC SW


9900

10200

10500

10800

0 30 60 90 120 150 180

[Na+ ] (

ppm

)


PCDC SWOPC SWPPC SW


200

250

300

350

400

450

0 30 60 90 120 150 180

[Ca2+

] (pp

m)


PCDC SWOPC SWPPC SW





Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)









775

885

99510

10511

0 30 60 90 120 150 180

pH


PCDC SWPPC SWOPC SW


ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2













Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls














050

100150200250300350400450

[Na+ ] (

ppm

)


PCDC DWOPC DWPPC DW


775

885

99510

pH


PCDC DWOPC DWPPC DW


7500

10500

13500

16500

19500

22500

[Clndash ] (

ppm

)


PCDC SWOPC SWPPC SW














1000

1400

1800

2200

2600

[SO

42ndash] (

ppm

)


PCDC SWOPC SWPPC SW


300400500600700800900

1000


[K+ ] (

ppm

)

PCDC SWOPC SWPPC SW


9900

10200

10500

10800

0 30 60 90 120 150 180

[Na+ ] (

ppm

)


PCDC SWOPC SWPPC SW


200

250

300

350

400

450

0 30 60 90 120 150 180

[Ca2+

] (pp

m)


PCDC SWOPC SWPPC SW





Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)









775

885

99510

10511

0 30 60 90 120 150 180

pH


PCDC SWPPC SWOPC SW


ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2













Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls















1000

1400

1800

2200

2600

[SO

42ndash] (

ppm

)


PCDC SWOPC SWPPC SW


300400500600700800900

1000


[K+ ] (

ppm

)

PCDC SWOPC SWPPC SW


9900

10200

10500

10800

0 30 60 90 120 150 180

[Na+ ] (

ppm

)


PCDC SWOPC SWPPC SW


200

250

300

350

400

450

0 30 60 90 120 150 180

[Ca2+

] (pp

m)


PCDC SWOPC SWPPC SW





Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)









775

885

99510

10511

0 30 60 90 120 150 180

pH


PCDC SWPPC SWOPC SW


ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2













Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (5)









775

885

99510

10511

0 30 60 90 120 150 180

pH


PCDC SWPPC SWOPC SW


ndash15

ndash10

ndash5

0

5

10

15

20

OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

Cl1Cl2













Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls














Mg2++ Ca(OH)2⟶ Mg(OH)2 + Ca2+ (7)


OPC PPC PCDC

co

mpr

essiv

e str

engt

h ga

in

Test cement

SO1SO2

504540353025201510

50


54

56

58

60

62

64

66

68

70

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement






(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls







(8)


4 Conclusion




Data Availability




Acknowledgments


References





















0102030405060708090

100

OPC PPC PCDC

g

ain

in co

mpr

essiv

e str

engt

h

Test cement





















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






















Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




Documents

Physicochemical Performance of Portland-Rice Husk Ash