Heat of Hydration of . Double-Shell Slurry Feed Grouts

R. 0. Lokken

Prepared for the U S . Department of Energy under Contract DE-AC06-76Rl0 7 830

Pacific Northwest Laboratory Operated for the US. Department of Energy by Battelfe Memorial institute

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PNL-7860

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DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsi- bility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Refer- ence herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom- mendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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SUMMARY

Samples o f doub le-she l l s l u r r y feed (DSSF) g rou t were prepared and t e s t e d i n a d i a b a t i c ca lo r ime te rs t o determine the e f f e c t o f waste concen t ra t i on and d ry b lend v a r i a t i o n s on t h e heat o f hyd ra t i on . Changes i n t h e DSSF waste concen t ra t i on had t h e g rea tes t impact on the o v e r a l l heat o f h y d r a t i o n o f the grou ts . Grouts prepared w i t h d i l u t e (100 t imes) DSSF had temperature r i s e s up t o 37°C l e s s than w i t h g rou ts prepared t h a t f o r u n d i l u t e d DSSF (15°C v s . 52°C). A91 t h e grou ts prepared w i t h u n d i l u t e d DSSF had temperature r i s e s t h a t exceeded 45°C.

P a r t i a l n e u t r a l i z a t i o n o f t h e DSSF w i t h ac ids r e s u l t e d i n delayed reac t i ons and lower temperature r i s e s than t h a t occu r r i ng i n t h e reference grou t . The temperature r i s e o f a DSSF g rou t prepared w i t h waste p a r t i a l l y n e u t r a l i z e d w i t h hyd roch lo r i c a c i d was -28°C a f t e r 300 hours of hydra t ion . The temperature r i s e f o r a g rou t made w i t h DSSF p a r t i a l l y n e u t r a l i z e d w i t h phosphor ic a c i d was -43°C. These values compare w i t h a temperature r i s e of >52"C f o r a g rou t made w i t h un t rea ted DSSF.

Decreasing t h e mix r a t i o f rom 9 l b / g a l t o 7.5 l b / g a l d i d no t s i g n i f i c a n t l y reduce t h e a d i a b a t i c temperature r i s e of g rou ts prepared w i t h p a r t i a l l y n e u t r a l i z e d DSSF waste.

ii

CONTENTS

SUMMARY .............................................................. ii

INTRODUCTION ......................................................... 1

PROCEDURES .......................................................... ~3

A D I A B A T I C CALORIMETER .......................................... 3

S I M U L A T E D WASTE ............................................... ~4

DRY BLENDS ..................................................... 5

GROUT PREPARATION ............................................. ~5

RESULTS AND D I S C U S S I O N ............................................... 6

CONCLUSIONS .......................................................... 14

RECOMMENDATIONS ...................................................... 14

REFERENCES ........................................................... 15

iii

INTRODUCTION

Dur ing the h y d r a t i o n and s e t t i n g o f doub le -she l l s l u r r y feed (DSSF) grouts , cons iderable heat i s generated by exothermic r e a c t i o n s w i t h i n t h e g r o u t . A d i a b a t i c temperature r i s e s exceeding 80°C have been est imated f o r DSSF g rou ts prepared w i t h a d r y b lend o f 47 w t % f l y ash, 47 w t % b l a s t furnace s lag, and 6 w t % t ype 1/11 Por t l and cement (Whyatt 1989(a), Lokken e t a l . 1992a). Performance c r i t e r i a f o r g r o u t d isposal s p e c i f y t h a t t h e temperature o f t h e g r o u t waste form must n o t exceed 90°C. To counter t h e increases i n temperature, i n e r t s o l i d s were added t o t h e dry b lend t o reduce t h e amount o f hea t -genera t i ng s o l i d s , thereby decreasing t h e temperature r i s e . Based on p r e l i m i n a r y r e s u l t s f r o m a d i a b a t i c c a l o r i m e t r y , a d r y b lend con ta in ing l imestone f l o u r was se lec ted as the reference f o r m u l a t i o n f o r 106-AN grouts(b) . The recommended d r y b lend consis ted o f 40 w t % l imestone f l o u r , 28 w t % c lass F f l y ash, 28 w t % ground b l a s t furnace s l a g , and 4 w t % type 1/11 Por t l and cement.

V e r i f i c a t i o n t e s t s , conducted d u r i n g FY-90 us ing t h e reference blend and s imulated 106-AN waste, showed t h a t t h i s combination o f waste and d ry blend s a t i s f i e d most performance c r i t e r i a when t e s t e d under s p e c i f i c cond i t i ons (Lokken 1992b). Resul ts f r o m a d i a b a t i c c a l o r i m e t r y fo r 106-AN grouts i n d i c a t e d t h a t t h e temperature r i s e was l e s s than 45°C a f t e r 450 hours o f h y d r a t i o n ; however, t h e temperature was s t i l l i n c r e a s i n g a t t h i s p o i n t and was approaching t h e 90°C 1 i m i t.

Because t h e temperature o f t he 106-AN g rou t approached t h e 90°C l i m i t , a s e r i e s o f experiments were conducted us ing s imulated DSSF t o determine which f a c t o r s c o n t r i b u t e most t o the generat ion o f heat . The u l t i m a t e goa l o f these and subsequent t e s t s i s t o i d e n t i f y a s u i t a b l e g rou t f o r m u l a t i o n t h a t minimize temperature r i s e w h i l e s t i l l meeting a l l o the r a p p l i c a b l e c r i t e r i a . M in im iz ing t h e temperature r i s e d u r i n g c u r i n g i s d e s i r a b l e f o r reducing

( a ) Whyatt. G. A. 1989. P i l o t - S c a l e Product i o n o f Grout w i t h Simulated Double-Shel l S l u r r v Feed. P N L - D r a f t . P a c i f i c Northwest Laboratory, Richland. Washington.

( b ) W . G. Richmond. "Formulat ion t o be Used f o r Tank 106-AN Waste Grout Tes t i ng . " Westinghouse Hanford Company I n t e r n a l Memo, 13922- 89-085, August 23. 1989.

1

thermal s t resses on the v a u l t a n d t o l i m i t i n g the detrimental effects on grout leach resistance (Lokken e t a l . 1992a).

This report describes the resul ts o f adiabatic calorimetry t e s t s conducted on undiluted a n d d i l u t e d s imulat ions o f DSSF grout. here, dry blend formulations, waste concentration, a n d mix r a t io were assessed t o determine which o f those factors have the greatest influence on heat generation during curing.

I n the work reported

2 I

PROCEDU Es

This section describes the operation of the adiabatic calorimeter system, the reference DSSF waste composition, DSSF neutralization procedures, the dry blend ingredients, and grout preparation procedures.

ADIABATIC CALORIMETFR

The adiabatic calorimeter system used in these studies consists of eight individual calorimeter cells and a common temperature measurement and control system. Figure 1 shows a schematic of a cell. The calorimeter cells consist of a 6-liter stainless steel Dewar, a water circulation pump, an immersion heater, and a l-liter stainless steel Dewar for the grout slurry. The heater i s controlled with a solid-state relay connected to the control system. The data acquisition system consists o f a relay multiplexer, a thermocouple amplifier/conditioner, and a 16-bit analog-to-digital converter.

Testing of grout hydration using adiabatic calorimetry is based on the premise that all the heat generated by the grout is maintained within the grout, thereby increasing the grout temperature. For the large grout disposal vaults. adiabatic curing conditions are expected, particularly for grout near the center of the vault. In the laboratory, adiabatic conditions are achieved by placing freshly prepared grout slurry into a stainless steel Dewar. A thermocouple is then inserted into the grout slurry. The Dewar containing the grout slurry is then placed into a second, larger Dewar containing water preheated to the initial grout temperature. A heater in the larger Dewar maintains the temperature of the water bath at the same temperature as the grout. In an ideal system, no heat transfer between the grout and the surroundings can occur because the temperatures within the grout and the water are the same at all times. The temperature of the grout is recorded every half hour during operation of the calorimeter.

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T W T /Thermocouples

FIGUREL. Schematic of an Ad iaba t i c Calor imeter C e l l

SIMULATED WASTF

The waste t h a t was prepared f o r t h e 1988 p i l o t - s c a l e t e s t o f DSSF g rou t product ion(a) was used i n these s tud ies . composi t ion o f t h e s imu la ted DSSF waste. For t h e f i r s t s e t o f t e s t s , bo th f u l l s t r e n g t h DSSF and DSSF waste d i l u t e d 100 t imes w i t h de ion i zed water were used. A d d i t i o n a l waste s o l u t i o n s were prepared by p a r t i a l n e u t r a l i z a t i o n o f DSSF us ing concentrated h y d r o c h l o r i c ac id , phosphor ic ac id . n i t r i c ac id , o r s u l f u r i c ac id . The pH o f t h e waste decreased f rom an i n i t i a l value o f -13.8 t o 13 a f t e r adding t h e ac ids . Dur ing a c i d a d d i t i o n , t h e temperature o f t h e s o l u t i o n inc reased by -13°C.

Table 1 l i s t s t h e analyzed

( a ) Whyatt. G. A . 1989. P i l o t - S c a l e Product i o n o f Grout w i t h Simulated Double-Shel l S l u r r y Feed, PNL-Draft. P a c i f i c Northwest Laboratory, Richland. Washington.

4

TABLE 1. Analyzed Composition o f Simulated DSSF Waste, g /L

S Q f S E i A1 B Ba Ca C r Fe K Mg Mn Mo Na S i Zn c1- NO2 PO4-3 NO^ ~

S04-2 TOC(a)

cent ra t i oq 22.4 0.136 0.6 0.573 1.26 1.49

0.32 3.01 0.068

0 e 502 2.93 5.36

27.2 5.4

5.1 1.556

11.5

122

186

( a ) T o t a l Organic Carbon a s EDTA and C i t r a t e

Several d r y blends were used i n these s tud ies . The i n d i v i d u a l m a t e r i a l s i nc luded b l a s t furnace s l a g , t ype 1/11 Por t l and cement and l imestone f l o u r obta ined f rom Ash Grove Cement West, c lass F f l y ash f rom Cen t ra l i a . WA. and a t t a p u l g i t e c l a y f rom Engelhard. f o r 23 hours p r i o r t o g rou t p repara t ion . The p ropor t i ons o f each i n g r e d i e n t a re l i s t e d i n t h e Resul ts sec t ion .

The d r y m a t e r i a l s were mixed i n a V-blender

Grout s l u r r i e s were prepared us ing a Hobart mixer and a w i r e whip. The waste was preheated t o 55°C and p laced i n t h e mixer . Room temperature d r y b lend was added us ing a mix r a t i o o f e i t h e r 9.0 l b / g a l o r 7.5 l b / g a l . A f t e r mix ing. approx imate ly 1 l i t e r o f g rou t s l u r r y w a s poured i n t o a s t a i n l e s s s t e e l Dewar, and t h e Dewar w a s p laced i n t o a ca lo r ime te r c e l l .

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RESULTS AND D I S C U S S I O N

The f i r s t se t o f a d i a b a t i c ca lo r ime t ry t e s t s was conducted us ing t h e exper imenta l m a t r i x shown i n Table 2 . The maximum recorded temperature r i s e f o r these e i g h t g rou ts i s shown i n t h e l a s t column o f Table 2. A l l t h e grou ts prepared w i t h u n d i l u t e d DSSF had temperature r i s e s exceeding 45OC. and the temperatures were s t i l l r i s i n g when t h e t e s t s were terminated. F igures 2 through 7 p l o t t h e data f o r temperature r i s e vs. t ime data. Figures 2 through 5 show t h e temperature r i s e o f g rou ts prepared w i t h f u l l s t reng th DSSF and DSSF d i l u t e d 100 t imes and w i t h blends 2 through 5. r e s p e c t i v e l y .

By comparing t h e two curves i n F igures 2. 4, and 5, i t i s ev ident t h a t t he waste concen t ra t i on c o n t r i b u t e s s i g n i f i c a n t l y t o t h e o v e r a l l heat generat ion. These curves are f o r t h e grou ts t h a t con ta in f l y ash and/or s lag . The temperature o f t h e b lend 2 and 4 grou ts w i t h u n d i l u t e d DSSF exceeded 95°C a t t he t ime t h e t e s t s were stopped (as a s a f e t y p recaut ion , t h e ca lo r imeters were programmed t o shut o f f when the g rou t temperature reached 97°C). Near t h e end of each o f these t e s t s , t h e r a t e o f temperature r i s e showed a s l i g h t upswing, poss ib l y i n d i c a t i n g a change i n r e a c t i o n mechanisms a t these temperatures. The curves f o r t h e grou ts made w i t h waste d i l u t e d 100 t imes suggest t h a t t he reac t i ons are n e a r l y complete a f t e r on ly 50 hours o f hyd ra t i on .

The e f f e c t o f waste concent ra t ion on t h e heat genera t ion o f b lend 3 ( w i t h o u t f l y ash o r s lag ) i s no t a s pronounced a s w i t h t h e o t h e r blends (see F igure 3 ) . Both s o l u t i o n s r e s u l t i n very f a s t i n i t i a l r e a c t i o n ra tes . A f t e r t h e f i r s t few hours, t h e r a t e o f temperature r i s e o f t he u n d i l u t e d waste g rou t became slower than t h e r a t e f o r t he d i l u t e d waste g r o u t . A f t e r about 100 hours o f hyd ra t i on , t he temperature o f t h e l a t t e r g rou t appeared t o s t a b i l i z e , w h i l e t h a t o f t h e u n d i l u t e d waste g rou t cont inued t o increase.

6

TABLE 7. Experimental M a t r i x and Maximum Temperature Rise f o r Ad iaba t i c Calor imetry o f DSSF Grouts. Mix Ra t io was 9.0 l b / g a l .

Dry B1 end Composi ti on(a), w t % B1 end Waste Temperature --- F S L Rise, "C

2 8 8 1 x 3.6 28.2 28.2 40 51.7(b) 3 0 0 1x 60.0 0 0 40 49.8(b) 4 0 8 1 x 6.7 0 53.3 40 55.8(b) 5 8 0 1x 6.7 53.3 0 40 45.8(b) 2 8 8 l O O X 3.6 28.2 28.2 40 15.4 3 0 0 l O O X 60.0 0 0 40 48.8 4 0 8 l O O X 6.7 0 53.3 40 24.1 5 8 0 l O O X 6.7 53.3 0 40 10.6

No. F/C S I C D i l . C ----

C = t m e 1/11 Por t l and cement F = fijl ash S = b l a s t fu rnace s l a g L = l imestone f l o u r Temperature was s t i l l i nc reas ing when t e s t s were stopped.

90

ao

70

60

50

100

40: 0 100 200

Curing lime, hr FIGURE,. Ad iaba t i c Temperature Rise f o r DSSF Grout Prepared w i t h Dry Blend

Number 2 (3.6 w t % Po r t l and Cement, 28.2 w t % Class F F l y Ash, 28.2 w t % Ground B l a s t Furnace Slag, and 40 w t % Limestone F l o u r )

7

100

90

80

70

60

50

1 40 ! I I

0 100 200 3

Curing Time, ht

YFIGURF 3. Ad iaba t i c Temperature Rise f o r DSSF Grout Prepared w i t h Dry Blend Number 3 (60 w t % Po r t l and Cement, 40 w t % Limestone F l o u r )

0 0

I I

0 100 200

Curing Time, hr 300

J I G U R F 4. Ad iaba t i c Temperature Rise f o r DSSF Grout Prepared w i t h Dry Blend Number 4 (6.7 w t % Po r t l and Cement, 53.3 w t % Ground B l a s t Furnace S lag , and 40 w t % Limestone F lou r )

8

0 0

c! 1 CI

5 P E

90

80

70

60

50

Full Strength

1 OOX Dilution

I I 0 100 200

Curing Time, hr 300

F I G U R F 5. A d i a b a t i c Temperature Rise f o r DSSF Grout Prepared w i t h Dry Blend Number 5 (6.7 w t % Po r t l and Cement, 53.3 w t % Class F F ly .Ash. and 40 w t % Limestone F l o u r )

F igures 6 and 7 show t h e temperature r i s e f o r t h e g rou ts prepared w i t h u n d i l u t e d DSSF and DSSF d i l u t e d 100 t imes, r e s p e c t i v e l y . These f i g u r e s c o n t a i n t h e same data shown i n Figures 2 through 5 and a re i nc luded t o p rov ide a b e t t e r comparison between d i f f e r e n t d ry blends. The data i n F igure 6 show t h a t t h e r e a c t i v i t y o f f u l l s t r e n g t h DSSF toward t h e d ry b lend cons t i t uen ts a re ranked: s l a g > cement > f l y ash ( i . e . . b lend 4 > 3 > 5). S i m i l a r l y , t he rankings f o r r e a c t i v i t y o f t h e d i l u t e d DSSF a r e cement > s l a g > f l y ash. The temperature curve f o r t he g rou t prepared w i t h equal amounts o f s l a g and f l y ash (No. 2 ) l i e s between the curves f o r t h e blends w i t h h i g h amounts o f s l a g (No. 4 ) and f l y ash (No. 5). However, t h e temperature curve l i e s c l o s e r the t h e f l y ash blend, i n d i c a t i n g t h a t an i n t e r a c t i o n , o r compe t i t i on between the f l y ash and t h e s lag, i s o c c u r r i n g d u r i n g hyd ra t i on . I n c r e a s i n g the f l y ash content i n t h e b lend would reduce the temperature somewhat, b u t the magnitude o f r e d u c t i o n would n o t be very g rea t .

Temperature, OC

0, 4 0, (0 0 0 0 0

w

9 s 5' VI

Temperature, O C

4

VI

A d d i t i o n a l t e s t s were conducted t o determine t h e e f f e c t s o f p a r t i a l n e u t r a l i z a t i o n o f t h e DSSF on t h e a d i a b a t i c temperature r i s e . these t e s t s was t o determine t h e e f f e c t o f a lower hydrox ide i o n concent ra t ion on heat genera t ion . It was suspected t h a t t h e h igh hydrox ide concent ra t ions present i n t h e DSSF r e s u l t e d i n d i s s o l u t i o n o f t h e g lassy phases o f t h e f l y ash and s lag , which increased the concent ra t ion o f reac tan ts .

The purpose of

Grouts were prepared us ing the re fe rence d ry b lend a t 9 l b / g a l and DSSF waste t r e a t e d w i t h 2 v o l % H3P04 o r 6 v o l i H C 1 . The data for temperature r i s e v s . t ime are shown i n F igure 8. Both o f t he p a r t i a l l y n e u t r a l i z e d wastes r e s u l t e d i n grou ts t h a t showed delayed reac t i ons compared w i t h t h e un t rea ted DSSF g r o u t . The t ime f o r t h e l a r g e s t temperature r i s e occurred a t approx imate ly 10 hours, 25 hours, and 75 hours, r e s p e c t i v e l y , f o r t he un t rea ted , t h e HC1-treated. and t h e H3POq-treated waste grou ts . A f t e r about 50 hours o f hyd ra t i on , t h e temperature r i s e o f t h e HC l - t rea ted waste g rou t appeared t o s t a b i l i z e w i t h a peak temperature o f about 73OC. which corresponds t o a 28°C r i s e a f t e r 300 hours o f hydra t ion . The temperature o f the un t rea ted and HgPOq-treated waste grou ts showed no s igns o f l e v e l i n g o f f a t t he t ime the t e s t s were stopped.

The n e x t s e t o f t e s t s w a s conducted f o r two purposes: 1) t o determine the e f f e c t o f p a r t i a l n e u t r a l i z a t i o n o f t h e DSSF us ing d i f f e r e n t ac ids, and 2 ) t o determine the e f f e c t o f decreased mix r a t i o on the heat generat ion. The pH of t h e DSSF was ad jus ted t o 13 us ing HC1, H3P04. HzSO4. o r HNO3. The dry b lend inc luded 30 w t % b l a s t furnace s l a g , 30 w t % c lass F f l y ash, 30 w t % l imestone f l o u r , and 10 w t % a t t a p u l g i t e c l a y . A t t a p u l g i t e was added t o the dry b lend t o min imize d ra inab le l i q u i d s . The cement was om i t ted f rom t h e b lend because on ly f o u r i n d i v i d u a l d ry m a t e r i a l s can be used i n the fo rmu la t i on . The mix r a t i o w a s 7 i n F igure 9 peak occur r waste g rou t

5 l b / g a l . D a t a f o r temperature v s . t ime f o r t h e grou ts are shown Three o f t he curves are very s i m i l a r , w i t h t h e main hyd ra t i on

ng around 50 hours. The main hyd ra t i on peak o f t h e H3POq-treated d i d n o t occur u n t i l about 150 hours o f cu r ing , which i s nea r l y

tw ice a s l ong as a t 9 l b / g a l (see F igure 8 ) . Because phosphate ions a c t a s a se t r e t a r d e r , and because decreasing the mix r a t i o increases the r a t i o o f waste c o n s t i t u e n t s t o d ry s o l i d s , more phosphate ions are a v a i l a b l e t o delay the onset o f t he hyd ra t i on reac t i ons . The temperature r i s e f o r t h i s g rou t

11

a f t e r 300 hours of hydration was -37°C. Nitric a n d hydrochloric acids have nearly the same effect on the heat generation, w i t h each result ing i n grouts t h a t h a d temperature r ises of -28°C af te r 300 hours of curing. Treatment o f DSSF w i t h HzSO4 resul ts i n a grout temperature r i s e of -33°C a f t e r 300 hours.

A s stated above, one of the objectives of the t e s t s was to determine the effects o f mix r a t io on temperature r i se . Comparing the curves from Figures 8 and 9 for the HC1-treated waste grouts shows almost no e f fec t of decreasing mix r a t io on the temperature r i s e a f te r 300 hours. The calculated temperature change i n go ing from a mix ra t io of 9 l b / g a l t o 7 .5 l b / g a l i s -4°C. This value i s based on decreased dry solids content a n d increased specific heat. Decreasing the mix r a t io , however, increases the r a t io of waste constituents t o dry so l ids , a n d , as discussed above, the waste contributes greatly t o the overall h e a t generated. Therefore, decreasing the mix r a t io may n o t be a n effect ive means of reducing the overall temperature increase i n DSSF grouts.

12

90

70

60

50

\ 6 voPh HCI

I I

0 100 200 0

Curing Time, hr

.FIGURE 8 . Ad iaba t i c Temperature Rise f o r Grout Prepared w i t h t h e Reference Dry Blend ( 4 w t % Po r t l and Cement, 28 w t % Class F F l y Ash, 28 w t % Ground B l a s t Furnace S lag , and 40 w t % Limestone F lour . Mix Rat io was 9 l b / g a l )

0 0

DSSF pH Adjusted to 13

80 - 70 -

" 3 " 4 --

40 I I I

0 1 00 200

Curing Time, hr 300

F I G U R E 9. Ad iaba t i c Temperature Rise f o r Grout Prepared w i t h P a r t i a l l y Neu t ra l i zed DSSF (Dry Blend was 30 w t % Class F F l y Ash, 30 w t % Ground B l a s t Furnace Slag, 30 w t % Limestone F l o u r , and 10 w t % A t t a p u l g i t e . Mix Ra t io w a s 7 . 5 l b / g a l )

13

CONCLUSIONS

.

DSSF g rou ts were t e s t e d us ing a d i a b a t i c c a l o r i m e t r y t o determine which f a c t o r s have t h e g r e a t e s t i n f l u e n c e on heat generat ion d u r i n g hyd ra t i on . The f a c t o r s assessed inc luded d ry b lend fo rmu la t i ons , waste concen t ra t i ons , and mix r a t i o . Based on t h e r e s u l t s obta ined t o date, t h e f o l l o w i n g can be concl uded:

The temperature r i s e f o r DSSF g rou t prepared w i t h t h e reference d r y b lend a t 9.0 l b / g a l exceeded the 45°C l i m i t .

The temperature r i s e f o r t h e grouts prepared w i t h u n d i l u t e d DSSF and d ry b lend h i g h i n s l a g o r f l y ash content was up t o f i v e t i m e s h ighe r than g rou ts made w i t h d i l u t e d DSSF. demonstrat ing t h e h i g h r e a c t i v i t y o f t h e DSSF waste toward t h e s l a g and f l y ash.

The temperature r i s e f o r t h e blends c o n t a i n i n g o n l y cement and l imestone w a s r e l a t i v e l y unaffected by waste d i l u t i o n , w i t h temperature r i s e s g r e a t e r than 48°C.

Grouts made w i t h DSSF t h a t was p a r t i a l l y n e u t r a l i z e d w i t h HC1 o r HNO3 had temperature r i s e s <30°C a f t e r 300 hours o f hyd ra t i on . These compare w i t h a temperature r i s e o f > 5 Z o C f o r a g rou t made w i t h un t rea ted DSSF and a s i m i l a r d ry blend.

0 Decreasing t h e mix r a t i o f r o m 9 l b / g a l t o 7.5 l b / g a l d i d n o t s i g - n i f i c a n t l y reduce t h e a d i a b a t i c temperature r i s e o f g rou ts prepared w i t h p a r t i a l l y n e u t r a l i z e d DSSF waste.

RECOMMENDATIONS

The s t u d i e s conducted t o date have d e a l t on l y w i t h measuring the a d i a b a t i c temperature r i s e s o f DSSF g rou ts . P a r t i a l n e u t r a l i z a t i o n appears t o be a v e r y

promis ing method o f reducing t h e temperature r i s e d u r i n g h y d r a t i o n o f DSSF g rou ts : however, t he t e c h n i c a l f e a s i b i l i t y o f t h i s process needs t o be assessed. A l l o f t he r e s u l t s discussed above were f r o m s i n g l e t e s t s . Rep l i ca te t e s t s a r e needed t o o b t a i n the des i red conf idence i n the r e s u l t s . Once formulat ions t h a t have acceptable heats o f h y d r a t i o n a r e developed, a d d i t i o n a l t e s t s a r e needed t o address t h e phys i ca l and chemical p r o p e r t i e s , i n c l u d i n g r h e o l o g i c a l measurements, d ra inab le l i q u i d s , compressive s t reng th , and leach res i s tance .

14

REFERENCES Lokken, R . 0.. P. F. C. M a r t i n and J . W. Shade. 1992a. D u r a b i l i t y o f Double- S h e l l Tank Waste G r o u t s , PNL-7835. P a c i f i c Northwest Laboratory , Richland. Washington.

. . Lokken. R . 0. 1992b. fo rmula t ion V e r i f i c a t i o n Study Resul ts f o r Tank 106-AM M a , PNL-7966, P a c i f i c Northwest Laboratory , Richland. Washington.

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