SOCIEIY OF PETROLEUM ENGINEERS OF AIME6200 North Central ExpresswayDallas, Texas 75206 %%SPE5028

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LONG-TERM EFFECTS OF HIGH TEMPERATUREON STRENGTH RETROGRESSION OF CEMIENTS

by

L. H. Eilers and R. L. Root

Dowell Division of The Dow Chemical CompanyTulsa, Oklahoma

@ (k+p~tighl 1974kericaaIIIGtiMG ofMining,Me@kgkaL endPetrolewnEogineem InrA

This paper was prepared for the 49th Annual Fall Meeting of the Society of Petroleum Engi-neers of AIME, to be held in Houston, Texas, October 6 - October 9! 1974. Permission to copyis restricted to an abstract of not more than 300 words. Illustrationsmay not be copied. Theabstract should contain conspicuous ac!cnowle~ementof where a~d by whom the paper i~ presented.Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETYOF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriatejournal provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to theSociety of Petroleum Engineers Office. Such discussion may be presented at the above meetingand, with the paper, may be considered for publication in one of the two SPE m.sgazines.

ABSTRACT

Neat Portland cement systems lose strengthand become permeable at temperatures above250F. This deterioration usually is moreextreme over the first few days or month ofheating but is usually not severe enough tocause disintegration of the neat cement.After this initial regression many neatPortland systems will regain a portion oftheir strength and reduce in permeability.This temperatureregression of cement canlargely be prevented by using about 35 percent very fine silica sand. The strength canbe maintained or increased but permeabilitywill increase. Most additives for oil xellcements can be included in such a silicastabilized system without extensive effectdue to temperaturesup to 600F. An exceptionto this is fly ashes and, to some degree, nat-ural pozzolans. These are stable at 450Fbut are loatng strength and recrystallizingat600F.

*References and illustrations at end of paper

INTRODUCTION

The deterioration of Neat Portlandcement at temperaturesabove 250F (12~0C)~as been know? for many years. Menzelproved that fine silica added to a Portlandcement paste would improve the strength ofcements cured at elevated temperatures.

h increasing number of wells are beingsubjected to these elevated temperatures eachyear. Deeper and hotter oil and gas wellsare being drilled and other wells are beingsubjected to hot water, steam, or fire floodmethods. High temperature geothermal wellsare also increasing in number each year. Thecement in these wells will be subjected toelevated temperatures from bottom to top. Itis probable, therefore, that the surface andintermediate strings on many of these wellsare not adequately protected from deter-ioration.

DEFINITION

The literature contains very few refer-ences to the effect of temperatures above

2 LONG-TEN EFFECTS OF HIGH TEMPERATURE ON STRENGTH RETROGRESSION OF CEMENTS SPE 5028

400F and most of these are references to 2,3,4 filled with water and the nipple ca>ped andkiln heat on Portland-silica cement blocks numbered. The capped pipe nipples wereWe desired to better understand what was placed in ovens and brought tc the appropriateoccurring in oil well cements containing temperature in eight ,ours. Preliminaryadditives when maintained at elevated ternper- tests were run for one day to one monthatures. For this prupose we chose several periods to s+lect the better systems forclass A, G & IIcements at several water further testing. Over 100 systems have beencontents, containing many of the usual given preliminary testing. Of these, 73 haveadditives such as silica, extenders, weighting been tested for six to twelve months and 42agents, retarders, and salt. The additives are continuing for two year testing.were tested one at a time in inhibited cementslurries with and without added silica. The Tubes were removed from the ovens andtest temperatures selected were 450 and opened at intervals of one month, three600F. months, six months, and one year. The indivi-

dual cement cylinders were measured, weighed,MATERIALS AND EQUIPMENT and permeabilitywas determirtzd, On the

first samples porosity was determined underThis investigation covered four Class G, magnesium perchloriate drying conditions.

three Class H, two Class A, one Class J, one Porosity measurements were discontinuedwhenlight weight, and one Chem Comp (expanding) it was determined that a week or more wascements. Average compositions of the A, G, & required to reach equilibriumand littleH cements are given in Table 1. Various informationwas obtained. The strength ofcommon additives such as extenders (including the samples was then determined and x-ray andfive fly ashes) retarders, weighting agents, differential thermal analysis made on theand.salt we~e included. All were tested with crushed samples.sf?.iconpr~sent and most without silicaadded. During the testing thus far only two of

Ithe 600F tubes and ncne of the /501?tubes

The mixing procedure followed closely have gone dry. Spare t~~beswere pulled forthe API schedule for preparing compressive those which had gone dry.strength cubes. Variations in water, mixingof extremely dense slurries, and addition of DATAsome extenders required slight variations inmixing technique. Rather than the standard A. Dimensional and Weight Stabilitytwo-inch cubes, one-inch diameter cylinders,1.25 inches long were prepared. Appropriate The coupon cylinders which wereamounts of effective retarders were added, stable in other ways did not change0.3 to 0.4 per cent retarder to A, G, and appreciably in size or weight. TheC!lemComp cements set at 200-225F, and 2 to only samples to change more than 1~ Per cent retarder to H and J cements set at per cent in size and 5 per cent in425F. The samples were set under 3000 psi weight were the high-water pozzolanpressure for 20 houns. The cylinders were cements with little or no silicacut to one-inch length to square the upper added. These also dropped to lesssurface before testing. The weight, size, than 200 psi compressive strengthand permeability of each cylinder was deter- and increased to more than 1mined. Three cylinders were used for initial millidarcy in permeability. Thesestrength. If any varied more than 10 per samples tended to increase in bothcent from the average, two more were run and size and weight as they deteriorated.the high and low values disregarded. It wasnoted early that the me-inch cylinders Some of the silica stabilizedproduced strengths about 85-90 per cent of pozzclanic ements, especially thosethe strengths of two-inch cubes of the same containing fly ashes, have developedcomposition. a roughened surface or an occasional

nodule along the water line of theThe samples were heated in capped steel sample.

pipe nipples containing water. For tests at450F, 1 l/4-tnch O.D. extra heavy black iron The samples at 600F which driedpipe was used. For tests at 600F, thick- out did not change dimensionallywalled 1 l/2-inch O.D. stainless steel pipe but lost weight. The weight couldwas used. Duplicate coupon cylinders of each be restored by rewetting the samples.test material were placed in the pipe withsteel washers as spacers to isolate systems. B. StrengthWhen a 15-inch long pipe nipple was filledwith coupons, the remaining space was half Strength results on neat cements

and cements with powdered and fine

SPE 5028 L. H. EILERS and R. L. ROOT

sili:a added are given in Table 2. If the initial cement was protectedEach Portland cement was checked it would remain so.wita35 per cent powdered silica(--325mesh) and with 35 per cent There was one notable exception infine silica (100-325 mesh). Selected that fly ashes were detrimental atG and H cements were checked with 600F but not noticably so at 450F20 and 50 per cent of e:lchtype during the first year. A series ofsilica. All the data g].venare the five fly cshes have been testedaverages of results of l:WOor mori with local.cements that might becements except for the Chem Comp, used with them. In all cases thethe Class J, the non-typical neat H strength has dropped after heatingand the non-typical G with 35 per three to six months at 600F.cent fine silica.

The cemen=systems which did notGenerally the neat cements are have enough Silic:a to prevent highweakened for the first c!ayof temperature retrogression,deterioratedheating at 450F and greatly very badly when additives wereweakened the first day cf heating included in the mix, An example ofat 600F. Thereafter they slowly this, included in Table 3, is thegain in strength but never become saturated salt system which lookedreally strong cements unless the normal with 35 per cent silica, butwater content is kept very low. which completely broke down in oneAlthough some of these csments day at 6CJ00Fwith or.ly20 per centdropped below 1000 psi strength the silica added. Similar results werefirst day, they could not be obtained with 10 per cent diatomace-considered to have completely ous earth and 12 per entbentonitedeteriorated and some low-water with no silica added.>mixes regained a remarkable amountof strength. The additicm of c. Permeabilitysignificant amounts of silicaimproved the strength of all port- The permeabilities of all cementland cement systems . Fifty per systems tested are high whencent silica by weight of Portland heated at 450 and 600F. Mostcement protected all the sements systems were initially measured infrom high temperature strength the range of 1 microdarcy (0.001retrogression. Thirty five per millidarcy) when cured at 200-225Fcent powdered silica also protected and in the range of 2 to 180 micro-all systems. Thirty five per cent darcies when cured at 425F. Afterfine silica (100-325)mesh protected heating at 450 or 600F all systemsten of the eleven systems tested increased in permeability. Afterbut allowed some deterioral:ionof heating one month or more theone class G. One class H cement minimum permeability measured waswas adequately protected by 20 per 0.06 mil.lidarcy(60 microdarcies)cent silica. In fact, it was not in the class J cement, and theextremely deteriorated when no maximum was about 10 millidarciessilica was added. The class J in some of the pozzolan cementscement required no additional without silica. Most stabilizedsilica. systems have settled at about 0.07

millidarcy to 0.40 millidarcy afterThe zesults with selected additives 6 months to one year.normally used in cement systems aregiven in Table 3. The cement A deterioration in strength wassystems which had enough silica to always accompanied by a greatprevent retrogression ccwld tolerate increase in permeability. Theremost additives without retrogression. were instances of great increasesThe silica-protectedsystems con- or increases followed by decreasestaining large amounts of extenders, in permeabilitywithout changes inwere definitely weaker than the strength. Cements containing 50neat cements but did not deteriorate per cent silica at 450F or 600Fduring heating. This rule also and others containing fly ash andapplied to silica-protected cement 35 per cent silica increasedcontainingweighting agents, salt, greatly in permeabilitywhileretarders, and similar additj:ves. remaining constant strength. Stabilized

& LONG-TERV EFFECTS OF HIGH TEMPERATURE ON STRENGTH RETROGRESSION OF CENENTS SPE 5028

cements containing high silica calcium silicate carbonate, wasextenders such as diatomaceous found as a small portion of someearth, perlite, or bentonite, cement systems at 450F. This iSincreased rapidly in permeability formed when C02 is present in afor the first month then reduced 10

Bsystem t at would normally produce

to 40 fold while the strength xonolite .changed very littie. Some of theseunusual permeability results were The crystalline portion of the non-accompanied by one coupon having typical neat class H cement coupons1.5 to 2 times the permeability of was chiefly tricalcium silicatethe other. hydrate at the beginning and also

after one year at both 450 andD. X-ray Identificationof Crystalline 600F. This seems odd since this

--

was the only cement hydrating tocrystalline tricalcium silicate and

The chief composition of all the the dry powder was low in tricalciumheated cement samples was non- silicate as indicated in Table 1.crystallinewittia few minorexceptions. This is shown in Table A discussion of crystalline compounds4. The neat cements and cements normally found in Portland cementwith silica all contained some isystems is given by H.F.W. Taylor .alpha dicalcium silicate hydrate(c25H) after the first day of DIFFERENTIAL THERMAL ANALYSISheating at both 450F and 600F.The more dicdlcium silicate present The differential thermal anaiysis hasin the sample the weaker the com- been used to analyze some of the systemspressive strength and the more after heating for six months and one year.permeable the sample. In the case We have been able to confirm the calciumof cements withno silica but hydroxide in the neat systems and to showcontaining small amounts of additives that traces of calcium hydroxide exist inand extenders this was the only some of the low silica systems where it wasidentifiable crystalline compound not picked up by x-ray. We have also beenand may have been 30 per cent or able to confirm alpha quartz which was notmore of the sample. Th s= samples

5shown by x-ray in some of the high silica

had lost all strength. systems.

When the cement coupons had been The silicates produce a rather complexheated s x morths or more, no alpha set of thermal results over a broad temper-dicalciur,silidate hydrate was found. ature range from 800C (1570F) to aboveThis had ~onverted to calcio-chon- 1000C. Rapid reactions with sharp peaks aredrodite in most of the neat cements not observed. We have not as yet completedand to xonolite in most.-ofthe interpretation of this DTA area.cements containing silica. Thesystems containing xonolite remained DISCUSSIONstrong. Xonolite was also the cry-stalline material found after 6 The neat cement systems tested cannot bemonths in the other strong Portland considered to have disintegrated in one yearcement systems containing additives at either 450F or 600F. There was strengthstabilized with silica. Exceptions retrogression and great increases in permea-were the systems containing fly ashes bility, most of which occurred in one day toor natural pozzolan. one month. More retrogressionusually

occurred at 600 than at 450F. Many of theseThe fly ashes and tbe natural cements recovered some of their strength andpozzolan produced 11A and 9A reduced in permeability in the next eleventobermorite at 450F and reyerite months. This deterioration appears to beat 600F in the Portland cement caused by production of alpha dicalciumsystems. These reyerite containing silicate and :alcium hydroxide. The recoverysystems are weaker than the xonolite occurs when these combine to produce calcio-= stems.-Y chondrodite and tricalcium silicate hydrate.

Coarse cements and low water content reducedHydrogrossular,a calcium aluminum the rate at which these changes occurred insilicate, was found as a small the set slurries upon heating and produced aportion of the Portland cement more stable cement.systems at 600F. Scawtite, a

SFE 5028 L. H. EILERS

Additior,sof silica (sand) stabilized thePortland canents against high temperatureretrogression. Several sources of silicawere initially tested. These were powderedsilica, fine silica~ brick dust, and slateflour, Diatomaceous earth could not be addedover the full range of testing without addingexcessive amounts of water. All would preventdeterioration if used in correct quantities.Less weight of powdered silica and finesilica sand were required than of the othersilicates. They were also the most econom-ical and changed other properties the least.

About 35 per cent silica appears to be enoughto protect most Portland cements againstdegradation at both 450F and 600F. Addi-tion of 20 per cent silic,swas not enough formost Portland systems, and addition of 50 percent silica produced extra bulking, requiredmore water, and resulted in increased perm-eability. With ten of the eleven Portlandtype cements zested there was no significantdifference between powdered silica (-325mesh) and fine silice (1[0 to 325 mesh). Theremaining class G cement responded muchbetter t~ powdered silica than to fine silica.The reason is not apparent from chemicalcomposition b=t may be the result a high freelime combined with a fine grind. It is knownthat this neat cement retrogressed veryrapidly when heated, over 600d fold increasein permeability the first day. It may bethat the coarser silica did not have enoughsurface area to react this rapidly. In anyevent, this type deterioration occurs rapidlyand is relatively easy to test.

The expanding cement reacted as a Portlandtype cement. It was readily stabilized bysilica. The sulfate could not be detected byx-ray or DTA after the first day heating andin one day only in the 450F heated system.The class J cement had been stabilized againslretrogressionas received and did not requireadditional silica. This system has had theleast variation in strength and permeabilityover the test period.

The improvement in strength and lowerpermeability of the silica stabilized systemsappears to be in the formation of xonoliteform of calcium silicate. This is a mono-cal:ium silicate rather than the dicalciumsilicate hydrate formed in neat cementsystems. Some dicalcium silicate hydrate wasfound in all the Portland systems after oneday heating. It appears that the di and tricalcium silicate solids in Portland clinkerhydrate to dicalcium silicate hydrate morerapidly than the dicalcium silicate can reactwith silica to form xonolite. Other invest-igators have found that as long as thedicalcium silicate hydrate remains as a minor

i R. L. ROOT 5

~isperseconstituent of the cement, very[fttledeterioration occurrs, but when it>ecomesa major portion then the c ment

5,s]ecomesporous and disintegrates .

Additives which do not react with Portland(or decompose under heat to something thatIoes react) may be placed in the silicastabilizedcement sy:~temwithout causing;erious deterioration. Such agents must bemed in moderation, that is the cement slurrynust still be the external continuous phase.&en weak materials are used in high concen-trations or when considerable additionalflatermust be included with the additive,then a weaker cement system will result. Itnay be more or less porou~ depeading on theadditive. When an additive is included in asystem that has a tendency to deteriorate,then the deteriorationbecomes more pronouncedand rapid. An explanation of this may bethat deterioration occurrs when weak dicalciumsilicate hydrate begins to predor.in~zeoverstronger types of cement (xonolite,tricalciumsilicate hydrate, or others) as the continuousphase in the cemen~. The inclusion of anadditive further dilutes the strong portionof the cement until it is no longer thecontinuous phase. Additives which react withPortland cement, that is pozzolans and someother extenders may have a variety of effects.If the reactive part of the additive issilica to form xonolite, as in diatomaceousearth or bentonite, than this can replacepart of the silica to stabilize the cement.If the reactive portion forms materials otherthan xonolite with cement, then the effect onthe cement system depends on the strength andporosity of this new material.

The fly ashes and some natural pozzolansformed reyerite at 600F over long periods oftime. From the strength data it would appearthat reyerite is not as strong as tobermoriteand xonolite. The reason for producingreyerite instead of xonolite in fly ashsystems is not understood but may be causedby the higher alkali content. Others havealso noted an undesirable reac ion betweenbhigh alkali cements and silica . It isdefinitely associated with a recrystallizationalong the waterline of the sample as is shownin Figure 1.

SUMMARY AND CONCLUSIONS

An investigation to determine the effectsof high temperatures (450-600F)on variouscement systems over extended exposure timeshave been undemay for approximately 18months. Tests during and at the end of thefirst year of exposure have provided thefollowing information.

6 LONG-TERM EFFECTS OF HIGH TEMPERATURE ON STRENGTH RETROGRESSION OF CEMENTS SPE 5028.

1. Neat Portland cment systems lose natural pozzolans cause a recrystallizationstrength and become permeable at temper- of the Portland cement to a weaker andatures above 250F. more permeable material. This recrystalli-

2.zation requires several months.

Temperature regression of most Portlandsystetn.zcan be :preventedby adding REFERENCESsilica.to obtain a calcium to silicaratio of about 1. This can be accom- 1. Menzel, C. A., Studies of High-Pressureplished by adding about 30 to 40 per Steam Curing of Tamped Hollow Concretecent silica. Block. J. Am. Concrete Inst. 7, 51-64

(1935) also Proc. Am. Concrete Inst. :11,3. Portland cements seem to respond better 125, (1935).

to silica finer than 100 mesh. If aminimum of silica is used it should be 2. Lea, F. M.: The Chemistry of Cement andfine powdered silica (325 mesh or finer). Concrete, Chemical Publishing Co., Inc.If excess silica is used it should be a N.Y. (1971) 399-4010coarser grind HO that excess water isnot required. 3* Taylor, H.F.W.: The Chemistry of Cements,

Vol. 1, Academic Press N.Y. (1964) 429.4. Class J cement is stabilized us received

and does not require added silica. 4. Jernejcic, J. and Jelenic, I., Propertiesof Autoclave and Therrally Treated

5. Deterioration of the cements appears to Molds Made from r-Ca2Si04 and Quartz atbe associated with the formation of C/S Ratios of 0.5 to 1.5, Cement andalpha di.calciumsilicate hydrate and Concrete Research (Vol. 4, 1974) 123-calcium hydroxide. In the stabilized 132.systems (both neat and with additives)this had converted to xonolite. The 5. Lea, F.M.: The Chemistry of Cement andsystems contai.nin.gxonolite remained Concrete, Chemical Publishing Co., Inc.strong. N.Y. (1971) 203.

6. Most nonreactive cement additives can be 6. Maycock, Norman J and Skalny, Marlin M.:admixed with n stabilized cement without Carbonation of Hydrated Calcium Silicatesadversely affecting the temperature Cement and Concrete Research (Vol 4stability. This includes salt, weighting 1974) 69-76.agents, Kolit@ mica and other bulkingagents. Addi!;ionof such agents to a 7. Taylor, H.F.W.: The Chemistry of Cements,system which has a tendency to degrade Vol. 1, Academic Press, N.Y. (1964)at elevated temperatures increases the Chapters 5 and 6, 167-286.degretiation.

8. Taylor, H.F.W.: The Chemistry of Cements,7* Reactive extenders and pozzolans appar- Vol. 1, Academic Press, N.Y. (1964) 425-

ently fall inl:otwc]classes: Those with 427.high silica but weak pozzolanic activityand those with high pozzolanic activity. 9. Diamond, S. and Thaulow, N.: A StudyThe first group includes the bentonite, of Expansion Due to Alkali-Silica Reactiondiatomaceous earth und expanded perlite. as Conditioned by Grain Size of TheThe silica may react and be considered a Reactive Aggregate Cement and Concreteportion of the silica to stabilize the Research (Vol. 4, 1974) 591-607.Portland cement. They produce a lightweight, low pmmeabi.lity cement.These agents IJhouldnot be added toPortland cement in the range of 5 to 15per cent in hot wells without adding ACKNOWLEDGEMENTabout 20 per cent extra silica to stabi-lize against ~iegredation. The authors wish to express their appre-

The extenders with high pozzolanicciation to the DoWell Division of The DowChamlcal Company for permission to present

activity include the natural pozzolaneand the fly aohes. At temperatures to

this paper. They also wish to gzemfully

and including 450*F, these produce aacknowledge the analytical work done by

strong materf.i~lwith ~silicastabilizedD. A. Wood, L. B. Spangle and G. L. Rirby

cements. At iztemperature of 600F, theof The Dwell Division and the data on cement

fly ashes and, to a Lesser degree, thecompositions supplied by Mr. John Marlin of

&i)owell Trademark The Oklahoma Portland Cement Company.

SPE 5028 L. H. EILERS and R. L. ROOT 7

APPENDIX-

Hydrogrossular - Calcium aluminum or calcium

~Q Crystalline Phases (For further iron silicate hydrates -Ca3(A1 or Fe)2Si3(urinformationsee Taylor - P. 168-286)]: si2c) 0122H20

Tobermorite (9A) - C5Si6018H2also revereldl,teDesignal:lon- Chemical nature - Xonolite - Ca6Si6017(OH)2A-C2SH - Alpha dicalcium eilicate, Ca2HSi04(OH) Xilchoanite - Ca3Si207Calcio-Chondrodite--Ca.5(Si04)2(OH)2sometimes Afwillite - Ca3(HSi04)22H20Phasex Scawtite - Ca7Si6018(C03)2H20S-C SH --2

Gamma dicalcium silicate - probably Reyerite - K ca14si24060(oHj55H20Ca2(HSi04)(OH)orthorhombic Alite - Tricalcium silicate from cement

C3A2H6 - 3Ca0 lA1203fiH20with possibly some clinker Ca3Si05fron aridsilica subst:ltution

C3A2H6 3CeOA1203 6H20 wiuh some iron or

Kllleb:randite- dicalcium silicate hydrate silica sumtitution possible

Ca2Si03(OH)2 Gyrolite- Ca Si O8 12 30 oH)46H20C6S2H3- Tricalcium silicate hydrate Andradite - Ca3Fe2Si3012Ca6Si207(OH)6 Magnetite - Fe304

C4A6S6 - Probably 1/2 (4CaO*3A12036Si02H20)- Dellaite - Ca6Si3033H2 (from decomposition ofsimilar to cl.inozoisite C2SH)

Ettringite - 3Ca0 A1203 3 CaS04 l 31 H20

TABLE I

CHmICAL COMPOSITIONS

A~GES OF CEMENTS TESTED

Range of Composition Non-Typical Non-TypicalMaximum Minimum H G

% Free Lime 1.80 0 0.25 1.80% TotalA.lkeli 0.86 0.44 0.85 0.55% CaO 65.35 63.89 65.02 63.89% Sio 23.74 21.84 23.57 21.98%AN~ ~e203 4.35 4.08

4.14 4.264.52. 2.22 3.32 3.93

Blal?eFlnenees* 3790(A) 2150 2150 3015Lose On Ignition 2.79 0.55 0.56 2.79(Calculations)% C3S 56.44 47.87 47.87 52.76% C2S 31.88 20.05 31.47 23.23% Cp 6.92 3.67 5.36 4.64x C4AF 12.02 8.64 10.10 11.96,

* Bleinefineness- The 3790was a claesA cementthe finest~.was 3450.

..

8 LONG-TERM EFFECTS OF HIGH TEMPERATURE ON STRENG?iHRETRCKRESSION OF C~ENTSSPE 5028

.

TASLE2

STSENGTS ANO PSSMSASILITPOF NEAT CBISNTS AND C- SILICASYSTDIS

~lae beet-lto450P and 600Funderste- preesureforperiodeup tooneyear.Data baeed on lrertse oftwoormorelystawexceptfornon-typicalC & B lyetemeandclaseJ andChemCompc~ente.

.

m% Set Initial Meet maximum Uinimum MaxPermeabilityCe9ant Water f Othm

~ J?siLz!?!!kl ~ Time* Time*J@_ Hde Time

Gor A 44 0 225 3600 450 1500 3 *46

1000 1 day 5.0 1 day~1400 1 mot 500 1 day 5.5 1 day

n 46 0 425 2150 450 3200 3 mc+ 2075 1 day 5.0 1 day+600 1700 1 MO+ 1100 1 day 7.0 1 day+

E 38 0 4.25 2350 450 4950 6 MO 2400 1 day 2.4 3 80.4000 6m0 1150 1 day 1.4 3 m.

.

.

AtyPSc 46 0 425 Soo 600 3975 6 w 1450 1 day 1*4M 32

6 MO.425 2150 600 5100 6 W. 3700 1 w. 0.27 1 m.

G 56 .35%Si2ica (Pwd) 225 3250 b~o 7600 1- 4500 1 day 0.12 6 m.+600 7500 1 day 0.14 6 m.+

e 54 35% si2ia(Fine) 225 3000 450 5825 :s 3400 1 day 0.50 6 MO.+600 7050 6 & 5750 1* 0.21 6 mm.

AtyPicG 54. 35% Siuca(yime) 225 3400 450 2950 1 yr. 1100 1 day 0.10 lday

600 6300 3 m. 1375 1 day 0.22 1 yr.

B 58 35% silica (Pud) 425 4650 450 8s00 lb 5200 1 day 0.09 lmm+600 8250 1 m. 5600 1 day+ 0.11 3at

E 56 352 Silica(yime) 425 4500 8500 180+ 7200 1 day 0.67 3 me+z 9650 J,mo 6050 1 day+ 0.3s 6-

e 50 20% Siuca(svd) 225 4450 450 5000 1 yr. 147s 1 day+ 0.19 lW+600 (A) 1 W. 1675 1- O*36 1 day

G 49 20% Siuca(?ime) 225 4200 450 2s00 1 day+ 2500 6=0 3.4 lyr600 2950 6 80+ 1225 1 day 3.9 1 yr.

w Ia two claes G cmta - one had reached 4550 tha other 17000 im one year at 600*F.

Gor E 61 50X Si~~ (2wd) 225 4000 450 S950 3 w 3750 ldayt 0.09 3e425 600 7100 6 =+ 4600 1 day 0.19 690+

Corm 56 50%Si2ica(Hne) 225 4100 450 9750 6 w+ 4325 lday 0.12 6w+425 600 8525 1 m+ 4900 1 de* 0.30 3a0+

J With or l~ithmt 20% Silica 425 3250 450 S200 1 m+ 5250 ; ~ O*O6 6 W.600 6S00 3- 4500 0.07 380+

Cha 68 352 Silica(svd) 200 2225 450 812S 6 w 5750 lday 0.22 6 w.600 10300 6 am 557$ lm O*1O 6 no.

l T* ~~ ~i~te the ~ or mimimm occurred at some point bamteen thie tin wid themextteettime-~~~~l-~ti~ thatse reachedwaeured8exlmumorminimumlt onemomthwhile othars reached thiepobt

.. .

SPE 5028L. H. EILERS and R. L. ROOT 9

TABLC 3

STRENCTNAND PER.NEASILI~ OF API CLASS G & H CWENTS WITS ADDITIVES

Samplee heated to 450 and 600*F under steam preesure for periods up to one year. Rewlte bzned on kplicatelamplea of a llngleaystamexceptforflyashreeultsfrom five ayatema. All percentasea baaed on weishtofAPI Cement.

Type Z % Set Initial Heat naximwm Ninimum Nax. Petm.cement Water Other ~ *ML pei at Time. pei lt Time Nds at Time

Corfl 87 to 91 1-1 Fly aah (5) 225 to 357; 450 8325 3 mO.+ 4850 Variee 0.37 6 mot35% Silica 425 600 5S00 1 day 1130 6 aO. 2.8 6 MM

- ---- ---

G w 1-1 Naturel Poz 225 3350 450 6300 1 day 2625 1 yr. 0.08 3 mo.35% silica 400 4350 1 dey 2025 1 mo. 0.27 3 mo.

m 69 10% Diecel 225 1300 450 .- 50 1 deyo Stlica

Not dst.50 1 day Not dst.

G 101 10% Diecel 225 1325 450 3950 1 yr. 2350 1 day 0.24 1 mo.20% Siuce 3S00 1 day 1950 1 w. 0.28 1 mo.

G 107 9% Parlita 200 2350 450 2875 1 yr. 23S0 6 MO. 0.16 6 mo.35x SLUM 3400 1 m. 1700 1 yr. 0.47 3 MO.

w 107 12X Demtomite 850 450 - - 125 1 day Not det.c silica 200 6co -- 50 1 day Not det.

G us 12% Bamtooite 200 10GO 450 2000 lm. 950 6 W. 0.20 3 MO.35% silica 600 3825 1 yr. 2000 6 W. 0.19 3 m.

m 216 3 perta Mat. Poz 225 2350 450 2700 1 day 650 1 MO. 0.10 1 w.O lilica 600 2500 1 dey 450 1 w* 2.8 1 MO.

c 53 25 Colite 225 4000 4450 6 MO. 2550 1 day 0.07 6 n.35% Silima z 6950 1 yr. 2425 1 day 0.24 1 MO.

c 65 WC Compomemt (A) 200 1600 450 4775 6 MO 3600 1 day O.U 6 MO.35% lilica 600 7775 1 yr 48s0 3 w 0.06 3 MO.

G 56 20% Salt 225 2175 450 5650 1 W. 4825 1 day35x Silima

0.22 6 MO.5675 1 yr. 4300 3 MO. .0.20 1 m.

@ 51 20% Ult20% Silica

225 2325 430 - - l;g 1 day 0.21 1 dey600- 1 day 5.4 1 dey

m 42 40Z Emtite35Z lilke

425 4000 8125 6 MO. ;;: 1 day 0.22 6 MO.z 10300 6 ~. 1 MO. 0.30 6 W.

10 LONG-TERM EFFECTS OF HIGH TEMPERATURE ON STRENGTH RETROGRESSION OF CEMENTS SPE 5028

TABLE 4

CRYSTALLINE COMPOSITION* OF HEATED CEMENTS

Cure TimeOne Day 0.5 to One Year

Type System Tamp,F Minor(10-30%~ Trace(-lO%) Minor 10-30% Trace(lO%)

Neat Cement 450 A-C2SH C3SH Calcio- Ca(OH)~(A-G-H) Ca(OH)2 ChondroLite G-C2SH

C3A2H6

600 Calcio A-C2SH Calcio- Ca(OH)Chondrodite Chondrodite Hillebrandi~e

A typicalNeat H

450 C6S2H3 A-C SHCa(dH)z C6S2H3Ca(OH)zC4A6S6

600C6S2H3 A-C SH C6S2H3 HydrogrossularCa(dH)z Ca

SPE 5028 L. H. Eilers and R. L. Root 11

Table 4 (continued) Cure Time0.5 to One Year

One Day Minor TraceType System Temp,F Minor(10-30%) Trace(-lO%) (10-30%) (lo%)

1 Portland - 1 or 2 450 -- Tobermorite (11A) Tobermorite Tobermorite(11A) (9A)

Natural Poz + silica Alite GyroliteQuartz

600 -- A-C2SH Reyerite ScawtiteQuartz

Portland + 35% silica 450 not determined Xonolite Magnetite+ 30% Hematite Andradite

600 not determined Xonolite MagnetiteAndradite Scawtite

Chem Comp 450 A-C2SH Tobermorite(llA) Xonolite Scawtite35% silica Ettringite

600 -- A-C2SH Xonolite DellaiteXonolite Scawtite

Neat Class J 450 sio2 Xanolite kmolite ScawtiteCa(OH)2 GyroliteA-C2SH

600 -- Xonolite Xonolite Scawtitesio2 ReyeriteA-C2SH

e Major portion was non-crystalline in all Cf3XHltS.

FIG. 1 - Recrystallizationalong the waterlineof stabilized cement containing fly ash.