Chester Clinic

Untitled

Economics of Lithium Technology for
ASR Control vs. Alternatives
By Claudio Manissero, Sales and Marketing Manager, FMC Corporation, Lithium Division
Randall Stewart, Lithium Technology Manager, The Euclid Chemical Company
Concrete durability, and more specifically Alkali Silica Reac- tivity (ASR) is fast becoming an item of great concern toowners following research conducted under the StrategicHighway Research Program (SHRP) and more recently the Innovative Pavement Research Foundation (IPRF). Even thoughthe issue of ASR has been around for several decades this research hasshown that traditional ways to address the issue were not as effective asoriginally thought, and field evidence of ASR occurrences in concretehave proven this, resulting in agencies and owners having to modifytheir specifications incorporating new technologies to minimize therisk of ASR. Why is this of concern to the ready mixed producer? After all, ASR does not show up as cracking and expansion for years, considerablyafter the concrete has been placed and paid for by the owner. To quoteJC Roumain, Holcim Cement, "The biggest competitive threat toconcrete is BAD concrete." In other words, if the concrete placed doesnot meet the design life expectancy, or if the concrete placed requires ASR Options Calculator Spreadsheet significantly more maintenance than planned, then the life cycle costarguments that clearly show that concrete is the material of choicebecome suspect, and force the owners to seek alternatives. One of the ASR Mitigation Options - Materials Costs
first steps taken is to change the specifications by requiring tightertesting procedures, but allowing options on how to meet the NOT VIABLE
standards. One of the new options that is appearing in a number of Low Alkali Cement
specifications is the use of lithium admixtures. Since this is new, it is a largely unknown option thus very difficult to evaluate with regards to NOT VIABLE
developing bids utilizing this option. In addition, the rumor in the marketplace is that lithium is "too expensive". As a consequence a Lithium Only
producer is too often likely to ignore this option and bid using better Low Alkali Cement
Lithium Plus
known options, at times ending up losing the bid to a more savvy producer who took the time to fairly evaluate all options and realized that the lithium option is not only an economical option, but at timesthe lowest cost option available to meet the specification requirements.
It is the purpose of this article to dispel rumors regarding lithium Example of Comparative Chart from ASR Calculator technology and assist the producer in fairly evaluating options While obviously not exhaustive, these examples demonstrate that lithium available to meet ASR requirements, and producing bids that will be technology is a practical, economically viable alternative that should be competitive and profitable.
considered when allowed in spite of its reputation of being "tooexpensive". Like all other new technologies, the reputation came from the According to state-of-the-art specifications, the options available for fact that it is difficult to understand the cost of the technology without ASR mitigation are: having considered all aspects, and providing a means to evaluate its cost 1. Use of non-reactive aggregates; compared to the other alternatives available. The purpose of this paper is 2. Use of suitable pozzolans; to dispel these rumors and provide the ready mixed producer a better 3. Use of lithium admixtures; and understanding of how to evaluate relative costs and make the best 4. Use of combinations of pozzolans and lithium. economical decisions in the bidding process. CONCRETE in focus ı 43
In the new specs, these options must pass tests that are specified, new aggregates and adjust accordingly to avoid any potential which are usually modifications of ASTM C 1260, Test Method for production issues.
Potential Alkali Reactivity of Aggregates (Mortar-Bar Method). When 2. Use of suitable pozzolans
deicing compounds are used that are salts of sodium or potassium, The most common pozzolan that can be used to prevent ASR is fly such as on airfield pavements, additional testing requirements may ash. However, not all fly ashes are alike. The most suitable ashes are include a further modification of this test that incorporates the deicer Class F fly ashes with a low lime (less than 8% CaO) content. In most in the soak solution used in the test. A number of researchers cases Class C fly ash is not acceptable or allowed. When using Class F recommend that ASTM C 1293, Test Method for Determination of ashes with a medium to high lime content (e.g. greater than 8%) Length Change of Concrete Due to Alkali-Silica Reaction, be used to testing must be conducted and the amount needed may be so high as to evaluate mixes, but this test takes two years for the results and cause real issues in set time, strength gain and in obtaining the therefore is not practical for construction purposes and, even though necessary amount of air in the mix (mostly dependent on the LOI of allowed on some specifications, it is very seldom adopted.
the ash). In addition, due to recent changes in the Clean Air Act that A traditional way of combating ASR was to utilize low alkali resulted in changes that power plants had to make in order to meet the cement at below 0.6% sodium oxide equivalent (Na new regulations, availability of good Class F ash has been decreasing 2O eq.). Over the years it has become apparent that this approach did not work as and is more difficult to get. Pricing of good quality Class F ash has also effectively as was previously thought. The important parameter should been increasing due to demand outstripping supply. The amount of have been total alkali of a mix rather than the alkali percentage of the Class F ash needed is based on the reactivity of the aggregates and cement component. In addition, this approach cannot compensate for should be determined by testing. external sources of alkali such as some deicing salts. In some areas Ground granulated blast furnace slag (GGBFS) may not be an where very low alkali cements are available (e.g. 0.4% Na option in cases where it is not readily available or the amount needed is lower), and the aggregates are moderately to mildly reactive and there too high to combat ASR where the new deicer ASR testing is used for are no sources of external alkali, this approach is still a viable option. airfield pavements (See Northwest Mountain Region Federal Aviation When the ready-mix producer is faced with having to bid on a Administration specification P-501, modified June, 2006), scaling is an project with specifications for ASR allowing those options, care should issue or there are concerns with finishing and curing concrete if not be taken in evaluating and costing out each option prior to submitting handled properly. a bid. This evaluation may take some effort at first, but once the Silica fume can be effective, however, care must be taken to ensure producer has determined his costs using locally available materials, this proper mixing and dispersion in the mix because clumps of silica fume evaluation becomes significantly easier for future bids. This evaluation in a mix can be the cause of ASR. Price of silica fume is also higher than will improve the chances of winning the bid based on the most cement, thus its use will in most cases increase cost significantly. economical option for the particular job, and allows the producer to Natural pozzolans can be very effective, but their availability is very increase his/her margins by minimizing risk and variability scarce throughout the US. If a pozzolan is used, in order to fully encountered when actually producing a job. Let's examine what the evaluate the costs the producer should ensure availability, determine if a cost factors are with each option.
silo is available for the material or make arrangements for one to be 1. Use of non-reactive aggregates (both coarse and fine)
installed, and mix design testing should be conducted.
This sounds like an obvious solution, however tests have gotten 3. Use of lithium admixtures
tougher over the years so that some aggregates that historically passed Lithium admixture (nominal 30% lithium nitrate solution) can be the tests are now deemed to be potentially reactive. Historical data for used with any aggregate source and allows the use of any local materials.
a particular aggregate is proving, at least in some instances, not to be a Amount of admixture needed is based on the alkali content of the mix reliable indicator due to changes in the aggregate characteristics in from the cement. Manufacturer recommendations for most aggregates different parts of a quarry. Availability of non-reactive aggregates has is 0.55 gallons of admixture for each pound of alkali supplied in a cubic also decreased over time, as their use was preferred in the past. Since yard of concrete, so the amount needed is based on both the quantity of reactivity of the aggregate is due to its mineralogy, it is unlikely that if cement used and the alkali content (Na2O % equivalent in the mill a particular aggregate were determined to be potentially reactive other report). This is referred to as the 100% dosage. Certain aggregates may aggregates from nearby sources would test as non-reactive. In many require more than the 100% dosage, which can be ascertained by cases, non-reactive sources may need to be imported from distant conducting the required testing. Using low alkali cement can minimize locations. Cost of transportation of aggregates must be taken into cost for this option. Lithium can be added as any other admixture and account and at present fuel prices this can significantly impact the in most cases addition of lithium will have minimal effect on the total cost. The producer must bear in mind that trucks must get to the properties of the mix except for a slight acceleration of setting time.
aggregate supplier empty and return full, thus transportation costs Care must be taken to ensure that according to manufacturer must be figured at twice the distance. In addition, the cost of the recommendations, 0.85 gallons of water must be removed for each aggregates will most likely be higher if they are not from the standard gallon of admixture added to maintain the proper w/c ratio. supplier or the producer's quarry, and provisions must be made to 4. Use of combinations of pozzolans and lithium
isolate the nonreactive aggregate from the aggregate normally used at This option combines the good qualities of both of the other the plant. Finally, in most cases it is prudent to test your mix with the options while reducing the cost of the mix. In general, it is possible to CONCRETE in focus ı 45

substantially reduce the amount of lithium needed in the mix by using it them to demonstrate the methodology. The figures in these examples in combination with a suitable pozzolan. The most common practice is are fictitious for illustrative purposes only - so you should adjust the to use it in combination with Class F fly ash. The concept is to maximize figures to reflect your actual costs of materials and manufacturing.
the amount of Class F fly ash used while meeting needed set times and The actual bid price should be established based on other costs and strength gain requirements, then top it off with lithium to achieve the anticipated margin. While the examples are based on actual recent desired ASR testing results. As a guideline, dosage can be reduced to 52% specification requirements, any reference to a specific project should of the dosage when the mix includes 25% (by weight of cementitious be avoided and is not implied. Each circumstance and each job will materials) low CaO content Class F fly ash. Lithium dosage is also be different.
decreased by the fact that it is calculated on the basis of portland cement; 1.) Example 1 – Pavement in a southern state.
therefore it is lowered by the fact that a portion of the cement was Requirements – Mix must meet ASTM C 1567, Test Method for replaced with the pozzolan. Determining the Potential Alkali-Silica Reactivity of Combinations of It is possible to design a mix incorporating Class C fly ash by the Cementitious Materials and Aggregate (Accelerated Mortar-Bar addition of lithium; however with most Class C fly ashes the lithium Method)¸ testing with a maximum expansion of 0.10% at 14 days.
dosage will have to remain at 100% and in fact can be higher than the (This procedure is a modification of ASTM C 1260 that evaluates standard dosage. Of course in these cases the amount of lithium will be cementitious aggregate combinations.) Standard mix requires 6.5 decreased by the fact that the mix will have lower cement content.
sacks of cement (611 lbs) for the desired strength at 0.45 w/c. The Testing must be conducted in order to determine if a mix with Class C project has tight timelines and penalties for lateness. The four fly ash is a real option with locally available materials.
options discussed above are allowed. Class C fly ash is not allowed.
Lithium can also be used in combination with silica fume, though Note: Both aggregates (coarse and sand) you have available are due to price of silica fume this is mainly applicable only to bridge decks.
marginally reactive as measured by ASTM C 1260 at 14 days. The No testing has been conducted on the use of lithium in combination cement you have available is low alkali cement at 0.48% Na2O eq.
with GGBFS, so testing must be conducted in order to determine if You have a silo for fly ash, which presently holds Class C fly ash. A lithium dosage can be decreased. good low lime (5.0% CaO) Class F fly ash is available.
So how do you put all the information together and develop figures for cost of the mix for the different options so you can decide how to bid Your standard mix (without the Class C fly ash) for 6.5 sacks is as a particular project? Let's look at a couple of examples and work through I BETHLEHEM
# MARYNEAL
L New Orleans
BUZZI UNICEM USA®
100 Brodhead Road
Suite 230
L Slag Grinding Plant Bethlehem, PA 18017
I Corporate Office *2004 Combination of RC Cement and Lone Star Industries 46 ı FALL 2006

The closest source of nonreactive coarse aggregate you find is 45 miles (90 miles roundtrip). Since it is a new source your cost is $ 9.50/ton. Therefore your coarse aggregate cost becomes: (Amount of aggregate x cost of aggregate) + (transportation cost x Admixtures, etc.
(1884 lbs x (9.50/2000)) + (1884 x (0.12/2000) x 90) = 8.95 + The closest source of nonreactive sand you find is 55 miles (110 miles roundtrip). Since it is a new source your cost is $ 7.25/ton.
Therefore your sand cost becomes:(1541 x (7.25/2000)) + (1541 x (0.12/2000) x 110) = 5.58 + 10.17 = Assume that the following are your additional costs/cu yd Interest on money (90 day pay, 6.0 % PA)$0.58Operating costs Finally your operating costs would increase an estimated $ 0.50/cu yd if you take into account that you will have to store and Fixed/Capital costs manage separate piles of aggregates.
So if you total in the changes Total cost per cu yd Unit Cost Cost/cu yd Option 1 - Nonreactive aggregate Estimate your transportation cost. Excellent rates from a common carrier currently run around $ 0.20/ton/mile on the low end. For a Admixtures, etc.
captive truck fleet to carry out the hauling, this cost should include fuel cost (minimum of $ 0.035/ton/mile), cost of a driver, and amortization of truck, taxes, insurance, maintenance cost and a usage factor. A conservative estimate is $ 0.12/ton/mile.
We stand behind the strength of our technical service and the performance of our products with the passion to meet the needs of our customers.
As one of the largest suppliers of portlandcement in the United States, you can counton our support. Holcim - a global companyproviding local solutions.
Corporate Headquarters Holcim (US) Inc.
6211 Ann Arbor Road 149205_Holcim.indd 1 ocus ı 47
Assume that the following are your additional costs/cu yd Interest on money (90 day pay, 6.0 % PA) Fixed/Capital costs Admixtures, etc.
Total cost per cu yd Option 2 - Use of suitable pozzolans Your price for Class F fly ash is $ 65/ton delivered. You can only Assume that the following are your additional costs/cu yd pass the ASR testing using 30% ash substitution. At this level you Interest on money (90 day pay, 6.0 % PA) cannot obtain the strength using 1:1 substitution, therefore you have to resort to 1.2 lbs of fly ash for each pound of cement replaced.
Since the testing showed that to control ASR you needed 30% by Fixed/Capital costs weight of cementitious materials; the amount of fly ash you will need is 611 x 0.3 = 183 lbs, the amount of cement in the mix will be 611 – (183/1.2) = 459 lbs cement.
Total cost per cu yd In addition, you do not have a silo so you must install a new silo adding to the fixed/capital costs. You also need to plan to increase the Option 4 - Use of combinations of amount of air-entraining admixture to maintain air.
pozzolans and lithium In this combination, the ASR tests can be met by lowering the Your costs can be expected to be as follows: Class F fly ash needed to 25% of the cementitious material and topping off with a reduced amount of lithium. At this level of ash when combined with lithium the strength gain requirements can be met using 1:1 substitution of cement. The amount of lithium required is expected to be 52% of the 100% dosage, even though testing should be conducted to confirm this. To determine the Admixtures, etc.
amount of lithium needed first calculate the amount of Class F fly ash used in the mix which will be 611 x 25% = 153 lbs of ash. From that determine amount of cement, 611 – 153 = 458 lbs. Then use the formula with the reduction factor to calculate the amount of lithium: 458 lbs x 0.48 % alkali x 0.55 gals/lb alkali x 52% reduction = Assume that the following are your additional costs/cu yd Interest on money (90 day pay, 6.0 % PA) Your costs can be expected to be as follows: Fixed/Capital costs Total cost per cu yd Option 3 - Use of lithium admixtures Admixtures, etc.
Use a price of $ 15/gal as a budget price. This is a figure used by owners in recent RFP documents, which allow lithium. This figure does include a fair margin for the ready mixed producer. Actual pricing is dependent on quantity and location for freight from manufacturingsites. Product is readily available nationwide. To calculate amount Assume that the following are your additional costs/cu yd Interest on money (90 day pay, 6.0 % PA) 611 lbs cement x 0.48% Na2O equivalent x 0.55 gals = 1.6 gals of 30% lithium nitrate solution Delivery cost (20 miles) Use of lithium allows the use of the local aggregates, does not Fixed/Capital costs affect properties of the mix, and will not require any capital investment (material storage and feeding systems supplied by the admixture company). Total cost per cu yd CONCRETE in focus ı 49
Option 2 - Lithium admixture In this example, it is clear that if all the other requirements of the job 100% dosage of lithium would be can be met with the use of the Class F fly ash, then this alternative is the 705 lbs cement x 0.48% Na2O equivalent x 0.55 gals = 1.9 gals most cost effective (Option 2). However, it can also be seen that if you go 30% lithium nitrate solution with straight lithium admixture the cost would be approximately the same as using non-reactive aggregate. The combination of pozzolan and lithium is significantly less than the use of non-reactive aggregates. This is generally true if the aggregate has to be transported any distance. In fact in this example if you work though the numbers this is true if the Admixtures, etc.
aggregates have to be transported 10 miles or more. When would using lithium be a better option overall? In some cases, the lithium is a separate line item that can be charged separately. In thesecases it can be seen that the combination of pozzolan and lithium is the Assume that the following are your additional costs/cu yd most cost effective alternative, and your margin would be larger because Interest on money (90-day pay, 6% PA) of the additional margin to be gained from the lithium at the budgeted price. What would be the best alternative if no Class F fly ash were Delivery cost (20 miles) available? In this case it probably would be the lithium alone, because Fixed/Capital costs there are other advantages to using your standard supply of aggregates, you can better predict how the mix will perform, and you have the built in margin for the lithium.
Total cost per cu yd $99.32 2.) Example 2 - Airfield pavement in the Midwest Option 3 - Combination of lithium with Class F fly ash In this example the basic mix is based on 7.5 sacks of cement for strength gain at 0.4 w/c. ASR testing requirements include passing a Amount of F Ash 705 x 0.25 % = 176 lbs modified ASTM C 1260 at 28 days at 0.1% expansion, and the new Amount of cement 705 – 176 = 529 lbs experimental deicer evaluation test1 (a modification to C 1260 whereby Amount of lithium the bar is immersed in deicer solution). The strength requirements are for 529 lbs x 0.48% Na2O equivalent x 0.55 gals x 52% = 0.73 gal 7-day flexural strength of 650 psi. The job has strict timetables andsignificant penalties for delays. No Class C fly ash or GGBFS are allowed. All four options previously discussed are allowed. Lithium is paid separately at a budget price of $ 15 / gal. Note: all materials available and costs are the same as the first example, except that the Class F fly ash available has moderately high lime content (e.g. > 7.5%). Testing indicates that with locally available allowed pozzolans, Admixtures, etc.
no mix with straight pozzolan will pass both the flexural strength requirements and the ASR testing. Real options are: 1) non-reactive aggregates, 2) lithium, 3) combination of lithium with Class F fly ash.
Using the same methodology as above the following are the relative costs: Option 1 - Non-reactive aggregate Assume that the following are your additional costs/cu yd Interest on money (90-day pay, 6 % PA) Delivery cost (20 miles) Fixed/Capital costs Admixtures, etc.
Total cost per cu yd From these calculations it is obvious that the combination of Class F Assume that the following are your additional costs/cu yd fly ash with lithium is the most cost effective. Even though straight Interest on money (90-day pay, 6 % PA) lithium appears a bit more expensive than nonreactive aggregates, it is still the second best option because lithium is paid separately as a line Delivery cost (20 miles) item, which is not available with the non-reactive aggregates option.
Fixed/Capital costs While going through the process for determining what the actual Total cost per cu yd $94.66 50 ı FALL 2006

costs of alternatives provided in thespecifications to address ASR are, anunderstanding of the methodology and usingit to cost out a project may make thedifference between winning or losing a bid. Inaddition, the methodology can help to insurethat all costs are taken into account duringthe bidding process and you do not findyourself in the situation of having bid too lowand risk losing money on a project. TheEuclid Chemical Company and FMCCorporation have collaborated to develop aspreadsheet that allows comparison of thealternatives and develop accurate costs for allthe alternatives avoiding a lot of thepaperwork. While this spreadsheet is in a Betaversion, representatives of either company canaccess the worksheet to help you implementthe methodology.
To reach the authors, contact: Claudio Manissero, FMC Corporation, Lithium Division, 2801 Yorkmont Road,Suite 300, Charlotte, NC 28208, 704-868-5305, [email protected] Randall Stewart, The Euclid Chemical All you need to know
Company, 19218 Redwood Road, Cleveland,OH 44110, 775-324-1590, RStewart@euclid about concrete color.
The views and opinions expressed in this Just one call is all it takes to learn how Davis Colors can provide you
with the number one concrete color brand in America, the most
article are those of the author and do not neces- widely used automatic dosing systems, and the personalized
sarily reflect the views and opinions of the marketing tools that will help you build your business. Call
National Ready Mixed Concrete Association. 800-356-4848 ext. 323 or visit www.daviscolors.com.
1This evaluation and specification requirement is primarily in the FAA P-501 specification and is in response to aggressive deterioration, attributed to ASR, as a result of the use of newer pre-snow deicing Tel: 800-356-4848 Fax: 323-269-1053 www.daviscolors.com
P I G M E N T S
2004 Davis Colors, a brand of Rockwood Pigments, Inc.
chemicals, such as potassium acetate. The evaluation of the cause of deterioration and mitigative testing procedures is currently being researched. For more information
please check out our
web site at www.nrmca.org
CONCRETE in focus ı 51

Source: http://www.nrmca.org/research/cif%2006-4%20asr.pdf