ML20008D769
| ML20008D769 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 07/24/1974 |
| From: | BECHTEL GROUP, INC., CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML20008D768 | List: |
| References | |
| NUDOCS 8007300656 | |
| Download: ML20008D769 (11) | |
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USE OF COARSE ACCRECATE WITH VA3IED PERCENTACE OF MATERIAL PASSING THE v200 SIEVE i
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Bechtel Associates Professional Corporation f.nn Arbor, Michigan July 24, 1974 0 0 ' 5.i 7
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BACKCRCUND
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At the outset of the initial construction phase on the Midland project, Inland limestone from Gulliver, Michigan, was selected for use as the coarse aggregate in concrete production. At the ti=e the project was reactivated, a sizable stockpile of the Inland =aterial re=ained which has subsequently been used in the concrete produced.
In reactivatinC the subcontracts and purchase orders for concrete production, the producers of Inland limestene were unable to make a cot =itment for any 1-1/2 inch aggregate, as it was all allocated to other uses.
A re-examination of the available aggregate sources suggested two likely ones:
Presque Isle limestone and Dru==ond dolSmite. Marblehead limestone was eliminated due to its lower specific gravite. Evaluation of typical tests such as chose summardzed in Table 1 led to th. conclusion that Drustond dolomite was the highest quality coarse aggregate available and every raaranable ef fort should be made to use it ot. the Midland project.
Most of the data reported in Table 1 are results of acceptance tests performed on the indicated aggregates.
Acceptance testing is performed to determine compliance with ASTM C-33 and enough additional information to provide a basis for an engineering evaluation to allow use of the aggregate. The C-33 testing gives infor=ation on some ite=s without minimum requirements such as specific gravity and provides for judgment in the results of other tests, such as alkali reactivity. To produce concrete of the desired quality, a core stringent requirement of 40 percent loss at 500 revolu-j
tions (Los Angeles abrasion) is given in our job specifications as well as a
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limit of 15 percent on flat and elongated parracles (an iten not considered b)
C-33).
The test results in Table 1 indicate that Drummond dolomite has a high specific gravity, low absorption, good particle shape, and a good abrasion value. When coupled with a petrographic analysis indicating a high-purity dolomite stone and successful trial mix reports, Drummond dolomite was accepted as a high-quality stone for use on the Midland concrete structures.
Aggregate tends to have increasing amounts of fine material passing the #200 sieve as it is rehandled in the production and distribution process. Experience has indicated this is a problem on the Midland project, sometimes leading to the rejection of aggregate for failure to =cet the 1.5 percent limit. The following is a chronology of events beginning with the first delivery of Drummond dolomite aggregate to the Midland jobsite:
On May 6,1974 the first boatload of Dru= mend aggregate arrived at the stone-dock in Bay City, Michigan, on May 22, 1974, the first shipment ' Drue=ond aggregate was delivered to the jobsite. A small quantity of Inland limestone was stockpiled on the jobsite at this time and in order to prevent mixing of the two sources, the incoming Drummond material war stockpiled separately until the Inland supply was exhausted.
On May 31, 1974 a second boatload of Drummond aggregate arrived at the stone-(~~)
dock in Bay City, Michigan.
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On June 3,1974, aggregate frc= the second boatload began arriving on site.
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Samples were taken and the loss by wash test on the 3/4 inch aggregate was 1.8%.
During subsequent deliveries to the jobsite, the testing frequency for loss by wash, ASTM C-117-69, was intensified. Results of this testing, as shown in Table 2, determined that the 3/4 inch aggregate exceeded the allow-able 1.5%.
Test results up to 2.3% passing the #200 sieve were obtained.
Shipnent of 3/4 inch aggregate was stopped on June 24, 1974 and the accunulated stockpile (approx 1=accly 3500 tens) was withheld from use.
Up to this time, no Drummend aggregate had been used.
Ninety-day cecpressive strengths on the six designs using stone with 0.4% and 2.0% loss by wnsh were available on June 19, 1974. At this time, field engineering requested a change to the specificatien to allow a =aximum of 2.5% loss by wash. This request was based on the. fact that the fine material passing the #200 sieve was dolemite dust and had no detrimental affect on 90-day compressive strengths.
All concrete placements scheduled for the week of June 24 to June 28, 1974 were re-scheduled pending resolution of the request to allow 2.5% loss by wash.
On June 27,1974,the field was notified by Project Engineering that the request to allov 2.5% loss by wash had been denied pending further evaluation.
On July 1, 1974, the concrete aggregate supplier deter =ined that 3/4 inch aggregate meeting specification requirements could be delivered by exclusively loading stone from the first boat shipment. On July 2, 1974, a 65 cubic ynrd
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concrete placement was made in the Auxiliary Building utilizing this "within
( )s specification" material.
Further in-depth evaluation of the request to allow 2.5% loss by wash was con-ducted by Bechtel and Consumers Power Ccmpany resulting in approval on July 2, 1974. This evaluation indicated that no detrimental effect to the concrete can he expected by increasing the permissible limit to 2.5%.
The proposed PSAR and specification change was discussed by telephone with the AEC-DOL staff on July 3, 1974. The A!C approved use of the 3/4 inch coarse aggregate with fines above specification limits in tlie Turbine and Auxiliary Building concrete, but reserved approval for the Reactor Building until they could review the proposed change in detail. Therefore, nortsl concrete pre-duction for the Turbine and Auxiliary Buildings was resumed on July 3, 1974, utilizing all avcilable 3/4 inch aggregate.
A joint meeting between the AEC, Consumers Power Company, and Bechtel was held in Bethesda, Maryland, on July 8, 1974, to discuss this change. At the con-clusion of the meeting, the AEC stated that there appeared to be no technical objections to the change to 2.5% loss by wash. The restriction on the use of the aggregste with higher than specification fines in the Reactor Building was therefore lifted.
The technical information and background supporting this change are presented in the rest of this report.
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AGGREGATE PRODUCTION. TRANSPORTATION AND HANDLING TECHNIQUES g
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The naturally occurring aggregates available in southern Michigan, are generally of low quality and are not suitable for the high quality concrete necessary for nuclear power plant construction. Suitable aggrecstes are all crushed at relatively distant quarries and transported by boat to a dock, where they are rehandled and trucked to the batch plant.
All the aggregates listed in Table 1 are handled in this same basic canner, and a relatively small portion of their production is used as concrete aggregate, the majority generally going to applications in the steel, chemical and agricultural industries.
Af ter the rock is removed from the quarry, it is crushed and classified into stock-piles of various size ranges. When an order is to be shipped, withdrawal from the stockpiles is made in appropriate proportions and blended on conveyor belts.
The aggregate.is then washed and loaded onto a boat by conveyor belts for shipment to the receiving stone dock.
At the stone dock, conveyor belts on the boat offload the aggregate into piles where it is rehandled by front-end loaders into trucks to be hauled to the batch plant stockpiles. Some front-end loader rehandling is done to build up the stock-piles and load the batch plant bins for concrete production.
Our experience to date on other jobs has been that it is nearly impossible to consistently maintain coarse aggregates below 1.5 percent of material finer than the #200 sieve when the aggregate has been shipped from the quarry by boat due to
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the several rehandlings required. This experience has been obtained with aggre-(,,/
gates from Inland, Drummond, and Marblehead.
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PROBLEM OF EXCESSIVE FINES IN COARSE ACCRECATE The system of prcduction of the coarse aggregate rssults in several handlings of the aggregate before it becomes a part of the concrete.
It has been 3echtel's experience that all aggregates which are produced and handled in this manner generate additional fine dust in the coarse aggregate.
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The pot ential problem of excessive fines was carefully examined and several alternatives were evaluated:
1.
Wash aggregates at jobsite or stone dock: This is a logical solutien to the cleanliness problem, but presents several other proble=s:
a.
Lead time for procuremen: and er?ction of (saipment, b.
Ecological problem of disposal of waste wash water, and c.
Availability of space for the plant to do this.
Since all these problems existed, it was concluded that the full magnitudo of the prcblem should be first evaluated.
2.
Change sources of aggregate: As discussed elsewhere in the report, this is not a practical solution, since all acceptable aggregates are handled in the same general manner and the problem would continue.
3.
Require quarry to modify production procedures: To consistently meet the f-~g A;TM C-33 requirement of limiting the amount of fines in the coarse aggre-
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gate to 1.5 percent passing the #200 sieve would require that the prods ter i
algnificantly increase his washing effort to eliminate more of the fines of j
the quarry. Past efforts at modifying producers procedures (both production and quality control) have met with very little success; presumably because such a mall percentage of their output is utilized as " Quality Controlled, rigidl specified" concrete aggregate that it would be infeasible for them to medify their operation to satisfy the requirements of such a small user.
4.
Evaluate eff ect of increased fines in coarse aggregate:
Information pre-sented in this report documents the results of this evaluation and indicates the mix suf fers no degradation in properties due to the additional amount of fines.
For this reason, this approach has been selected for solution to the problem.
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SOLUTION g
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As previously indicated, the most practical alternative appears to be to adjust the specification limits upward to 2.5 percent material allowable passing the #200 sieve. To place this value in the proper perspective, note that:
1.
The maximum amount of coarse aggregate in th0 structural concrete mixes is 2005 lb/cu.yd (3-2 mix). The proposed allotable increase would permit a maxi =um of 20 lb/cu.yd additional fine material (0.01 x 2005).
2.
This corre.sponds to a tolerance of + 1% (NIOiCA certification requirement) in weighing cementitious materials. The hi3 est comentitious content of h
the proposed mixes is 751 lb/cu.yd (E-2 mix). This is a difference of 15 lb/cu.yd of cementitious material which could occur and not violate speci-fication requirements (0.02 x 751).
3.
ASTM C-33 permits up to 5% material passing the #200 sieve in the fine aggregate. Jobsite tests generally show 0.6% material passing the #200 sieve. The maximum amount of fine aggregate in the proposed structural concrete mixes is 1515 lb/cu.yd (B-1).
With appropriate trial mix adjusc-ments, the sand could, under the specifications, add 67 lb/cu.yd of material passing the #200 sieve (0.044 x 1515).
As shown in Table 3, concrete made with Drummond dolomite exhibited the lowest creep and volume change of any concrete used for the post-tensioned containment structures for ten different nuclear plants.
This condition occurs due to the use of the dolomite coarse aggregate.
It is well known that the elastic properties of the coarse aggregate greatly influence the modulus of elasticity and creep characteristics, as well as the strength of the concretes produced. Drutnond dolomite is an extremely strong, dense aggregate with a high modulus of elasticity and hence confers these properties on its con-cretes. These concrece properties are, of course, influenced to some degree by the other materials and mix proportions used but she coarse aggregate properties are the primary cause of differences between these mixes since the mixes are generally ccmparable in other respects.
Creep tests were performed by casting sealed 6 x 18 inch cylinders and hydrauli-cally loading them to 1530 psi at age 180 days. Measurements of their deforma-tion were made using Carlson strain meters. These measurements, when plotted on a semi-logarithmic grid allow projection of the values to 40 years.
A tentative revision to ASTM C-33, published with C-33 in the 1973 Annual ASTM Standards, Part 10, would provide for variances such as the present item by stating in Paragraph 8.3: " Coarse aggregate having test results exceeding the limits specified... may be accepted provided that concrete made with similar aggregate from the same source has given satisfactory service when exposed in a similar manner to that to be encountered; or, in the absence of a demonstrable service record, provided that the aggregate produces concrete having satisfactory characteristics when tested in the laboratory."
Two trial concrete mixes, as shown in Table 4, were made in an identical manner with identical materials, the only exception being the amount of material passing
_Y the #200 sieve. 0.5 percent in the washed case, 2.0 percent in the unwashed case.
[V The fresh concrete properties were identical and the strengths ere quite similar with both concretes exhibiting almost the same strength at 7 days, the washed 5
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i aggregate concrete slightly higher at 28 days, and the unwashed aggregate con-crete slightly higher at 90 days.
s It is reasonable to expect that the higher 90 day strength of the unwashed aggregate concrete is due to the fine, extra dolomite dust reacting with the l
fly ash to produce a better pozzolanic reaction and hence more cementiticus j
material. From these tests it is cencluded that the additional fine caterial j
is not detrimental to the compressive strength of the concrete.
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Thus, it is concluded that it is technically acceptable to provide for the use j
of coarse aggregate under the circumstances outlined in this rr. port with an amount of fines passing the #200 sieve not to exceed 2.5 percent.
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y TAPTE 1 - PROPERTIT': t'F CO/ R S t* A CC P !'G A TE r.
pp0PtRTY CAME.Wr6.16 ATTS Specif ic.a t f or.
Drumrrard lehrd irnro e Isle t rtide.1 Petstr< cents Dolon. i t e (1) 1.ir e s t e,r.c (2)
I.t re st one (1) 1.tr e s:c.s (3) 111 72 3/4 1 D2 3/4 1-17 2 3/4 stie, sn.
1 /2 3/4 1-1/2 3/4 Steve analysis I passing 2 in.
100 100 100 ICG 160 1-1/2 90-100 91 99 94 94 1
20-55 100 36 100 34 100 46 28 100 3/4 0-15 50-100 6
96 9
97 13 3
3 93 1
41 1/2
'3/8 0-5 20-55 1
43 2
29 0
34 d4 0-10 8
6 6
da 0-5 4
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Fineness modulus 8.02 6.49 7.90 6.65 7.93 8.03 6.66 Amount passing #200 2
sieve, I (C117) 1.5 ma x.
1.0 0.4 1.2 0.95 0.7 n.6 1.1 Dry rodded vt. IL/cu, 103.2 107.4 92.4 94.4 ft.
Specific gravity (C127) 2.81 2.82 2.65 2.68 2.62 2.51 2.59 Absorttion, %
0.4 0.5 0.4 0.4 1.1 3.4 4.1 Flat & elont.ated particles, 1 15 max.
5.2 3.3 2.9 5.4 18.7*
Cimy lumps & f riable particles (C142) 0.0 Los Angeles abraston 40 max.
20.9 23.4 25.9 Scratch flandnese l
C (C235) 5 max.
mone 0.4 0.4 O
- j. + i Soundness (CBS) 18 mau.
0.2 3.8 4.2 (a%N Fotential Reactivity (C289) innocuous i
HOTE: TEST $ AHE TYPICAL (1) sample obtained at the quarry
- did not meet. 6pectfscation requirements (2) sample obtained at the jobsite (3) source of sample undetermined t
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TABLE 2 DRUMMOND DOLOMITE RESL'LTS OF 1-1/2 INCH WASHES Date Locatien Passing #200 o-17 Incoming 1.2% (Ave. of 3) 6-19 Incoming 1.7% (Ave of 3) 6-20 Belt 1.3%
6-20 Stockpile 1.4% (Ave. of 3) 6-27 Belt 1.2%
6-27 Belt 1.6%
6-27 Belt 1.5*
7-1 Belt 1.8*
7-1 Belt 1.2%
7-1 Belt 0.5%
7-1 Belt 1.9%
RESULTS OF DRL 210ND DOLOMITE 3/4 INCH WASHES Date Location Passing #200 2-12 Acceptance tests 0.5%
5-24 1st Inceming 0.5%
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6-18 Inecming (Belt) 2.0%
6-20 Incoming (Stockpile) 1.8%
6-21 Incoming (Steckpile) 1.7%
6-26 Stockpile 2.0%
6-27 Belt samples @ 0900 1.7%
6-27 Belt samples @ 0900 2.0%
6-27 Belt samples @ 0900 1.8%
6-27 Belt samples @ 0900 1.6%
6-27 Belt samplet @ 0900 1.8%
6-27 Belt samples @ 1500 2.3%
6-27 Eelt samples @ 1500 1.2%
6-27 Belt samples @ 1500 2.0%
.6-27 Belt samples @ 1500 2.0*
6-27 Belt samples @ 1500 1.4%
6-28 Belt samples 0 0850 1.4%
6-28 Belt samples 0 0850 1.6%
6-28 Belt samples @ 0850 1.5*
6-28 Belt samples @ 0850 1.5%
6-28 Belt samples @ 0850 1.4*
6-28 Belt samples @ 0850 1.6%
6-28 Belt samples @ 0350 1.7%
6-28 Belt samples 0 0850 1.5%
7-1 Belt samples @ 1050 1.8%
7-1 Belt samples @ 1050 1.9%
7-1 Belt sr.mples @ 1050 2.l*
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7-1 Belt samples 91050 1.8*
(,N) 7-1 Belt samples @ 1050 2.1*
7-1 telt samples @ 1050 1.8*
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7-1 Belt' samples @ 1050 1.9%
7-1 Belt samples @ 1050 1.9%
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1 TABLE 3 - TYPICAL CONTAINMENT-STRUCTURE CONCRETE PROPERTIES
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4 TYPE OF AGCRECATE USED Drummond Alluvial Quart River Cravel Oolitic Lime-Average of Dolomite Cranite Shale stone Ten Jobs (Palisades)
(Calvert Cliffs)
(Rancho Seco)
(Turkey Point)
Concrete Properties Unit Weigl.t. PCF 150.0 145.2 153.4 143.2 148.4 Aggregate Properties Specific Cravity 2.82 2.59 2.84 2.44 2.75 Absorption Capacity, I 0.3 1.0 0.6 5.1 0.90 1-Elastic & Creep Properties
- Creep + Autogenous volume 113 335 305 295 270 change, millior.ths Creep + Elastic Deformation +
283 600 555 555 544 Autogenous volume change, millionths i
Mechanical & Thermal Properties **
Compressive Strength, psi 8620 7930 8180 7760 7900 i
Modulus of elasticity, psi x 106 8.3 5.4 5.9 4.6 5.5 CD C?
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- All values are projected to 40 years and represent specimens loaded to 1530 psi at age 160 days at temperature 70-73F
- All values given are at age 180 days.
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TABLE 4 - DOLOMITE WITH FLY ASH TRIAL MIXES-UWASPET AGGREGATE-COMPARISON s
Trial Mix E-1 (6000 pai @ 90 davs. 3/4 in. max. size aggregate)
Washed Unwashed l
Material paesing #200 sieve, %
0.5 2.0 Materials for cu yd batch used in trial mix:
cement, Ib 609 609 fly ash, Ib 105 105 sand, Ib 1303 1303 3/4'in. aggregate., Ib 1735 1735 water, Ib 265 265 air entraining agent, oz 17.5 17.5 water reducing agent, oz 12.2 12.2 Fresh concrete properties w/c+p 0.37 0.37 slump, in.
4-1/4 4-1/4 i
- air, 5.7 5.7 t
temperature, F 66 66 1
Strength test results:
(all are average of 3 cylinders) 7 days, psi 4090 4110 28 days, psi 5500 5380 90 days, psi 7020 7290 Weight of material passing #200 sieve included in coarse 9
35 aggregate, Ib/cu yd I
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