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Portland-limestone Cement Presented by Derek Townson

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Presentation on theme: "Portland-limestone Cement Presented by Derek Townson"— Presentation transcript:

1 Portland-limestone Cement Presented by Derek Townson
June 16 - BCRMCA Board of Directors' Meeting and Town Hall Meeting in Nanaimo, BC

2 Portland-limestone Cement (PLC)
Background on PLC Adoption Process in Canada PLC Concrete performance & durability tests There are 3 main subjects that I will be covering today with regards to PLC. They are: Background information on PLC. What it is and where its been used. The process that has been used here in Canada to adopt PLC in the CSA Standards, and Results of Canadian durability testing of PLC concrete.

3 PLC IS NOT NEW Used successfully in Europe for over 25 years in a variety of applications and exposure conditions New Only To Canada The first thing everyone should realize is that PLC is not new. It first appeared in Europe some 43 years ago, and has been successfully and extensively used in Europe for over 25 years now. This is not a new cement type. It is simply new to North America. The limits on the limestone content of Canadian PLCs is less than that currently permitted in Europe. This was done to ensure that we would be well within the window of European experience with PLCs.

4 Gotthard tunnel, Switzerland
Longest train tunnel worldwide with 57 km length Fastest way to pass through the alps Cement used: CEM III: concrete in contact with high sulfated water CEM II/A-D 52,5: shotcrete and precast CEM II-A- L: concrete for paving Here are some examples of applications of PLC in Europe. This is the Gotthard tunnel in Switzerland. It is 57 km long and used CEM II A-L cement for the concrete paving. This is the most common PLC cement used in Europe and it contains up to 20% limestone. ASR and PLC

5 Use of CEM II A-L 42.5 R in precast industry - Italy
Here CEM II A-L cement is being used in precast concrete applications in Italy. 13/04/2017 HGRS_Title

6 Use of CEM II A-L 42.5 R in precast industry - Germany
Again PLC is being used, here in a structural precast concrete application in Germany 13/04/2017 HGRS_Title

7 Historical use of limestone cements
1965 Heidelberger produces 20% limestone cement in Germany for specialty applications (Schmidt 1992) 1979 French Cement Standards allows limestone additions. 1983 CSA A5 allows 5% in Type 10 (now GU) cement 1990, 15+/-5% limestone blended cements being used in Germany 1992, in UK, BS 7583 allows up to 20% in Limestone Cement 2000 EN allows 5% MAC (Typ. Limestone) in all 27 common cements, as was commonly practiced in various European cement standards prior to that. 2000 EN creates CEM II/A-L (6-20%) and CEM II/B-L (21-35%) 2006 CSA A3001 allows 5% in other Types than GU 2004 ASTM C 150 allows 5% in Types I-V 2007 AASHTO M85 allows 5% in Types I-V This slide shows the historical limestone cements around the world. As far back as 1965 Germany was using PLCs. Over the years many European countries adopted limestone cements with increasing levels of limestone content. In 1983 Canada adopted 5% limestone additions in Type 10 (GU) cement. In 1990 Germany was using PLC with 15% limestone. In 2000 EN created CEM II/A-L cement with up to 20% limestone content. North America has lagged behind badly. In 2003 Canada extended the 5% limestone content limit to all cement classes. The United States only allowed 5% limestone additions in 2004, and more recently in 2007 in the AASHTO M85 Standard.

8 Cement types sold in Europe (according to Cembureau)
PLC had the largest use in 2004 This slide shows the increase in the use of limestone cements in Europe. The red band through the chart is the percentage of total cement production in Europe that is CEM II A-L limestone cement with a limestone content of from 6 to 20%. It now occupies over 30% of the European cement market. It should also be pointed out that the yellow segments noted above represent CEM II Portland-composite cements which also contain limestone. In 2004 the combination of CEM II Portland-limestone cement and CEM II Portland-composite cement represented over 43% of the European cement market. Most portland-composite cements contain limestone too!

9 CSA A3000-08 Portland-limestone cement — a product obtained by
(a) blending portland cement and limestone or (b) intergrinding portland cement clinker and limestone, to which the various forms of calcium sulphate, water, and processing additions may be added at the option of the manufacturer. Notes: (1) Limestone is designated with the suffix L. Its proportion is indicated in Clause (2) Portland-limestone cement may be produced by intergrinding or blending, or a combination of both. The attainment of a homogeneous blend, in the dry state, of any two or more fine materials is important. Appropriate equipment and controls should be provided by the manufacturer. The 2008 edition of the CSA A3000 compendium of cement Standards defines PLC as follows: ( read text from the chart). It is safe to say that while the Standard permits either a blending and or intergrinding of the cement and limestone, the vast majority if not all of the PLC that will be sold on the market will be interground. Testing and trial grinds of PLC have shown that intergrinding is the best method to use in producing PLC cements of similar performance characteristics to existing Portland cements.

10 PLC Adoption Process in Canada
Step 1 Initially a literature review on Portland-limestone cement (PLC) by Doug Hooton, Mike Thomas & Michelle Nokken was undertaken. The literature review revealed benefits and challenges with respect to PLC. Now lets discuss the Adoption Process that was used to adopt PLC in the Canadian cement and concrete standards. First of all a literature review on PLC was conducted by Hooton, Thomas and Nokken on behalf of the CSA A3000 Technical Committee. This literature review has been published as a CAC publication with number SN3052. The publication is available through the Portland Cement Association. PCA website: CAC Publication SN 3053

11 PLC Adoption Process in Canada Step 1
May 2007 Literature Review: General Summary Advantages: 10% GHG Emissions Reduction. Uncertainty: Carbonation, Sulphate exposure and Potential for Thaumasite Unknown – Performance of PLC with HVSCM mix designs

12 May 2007 Literature Review: General Comments
Results reported in the literature reviewed appears to be affected by the quality and particle size distribution of the limestone used and whether the limestone was interground, blended, or added at the mixer. Since limestone is easier to grind than clinker, production to constant Blaine fineness will result in coarser clinker and reduced performance. Therefore, proper interpretation of the data needs consideration of these effects.

13 PLC Adoption Process in Canada
Step 2 Various Canadian cement companies produced prototypes of PLC at their plants. Chemical and physical analyses were performed with those products. Concrete performance and durability tests were and continue to be carried out at universities and CAC member companies.

14 PLC Adoption Process in Canada
Step 3 The tests performed with Canadian materials confirmed the findings from the literature review and findings from the European market. The prototype GULs showed, after initial optimization, similar concrete strength as GUs. Similar concrete strength  similar durability Due to mixed results from the literature review, PLC, is not to be used in concrete subject to sulphate exposure.

15 Durability Tests carried out in Canadian
PLC cements were produced in different grinding circuits by five cement companies: Clinker contents with C3A  4.5 to 12% Limestone content 3% to 19% Mortar tests and chemical analyses performed Concrete made with w/cm ratios  0.35 to 0.8 Cement content  225 kg/m3 to 420 kg/m3

16 Concrete Tests carried out with Canadian materials
Concrete tests with: 10% to 15% PLC Slag (15, 25, 30%, 50%) and fly ash 25% Slump, slump retention and air were measured Durability tests were performed, e.g. RCP, freeze/thaw, salt scaling, shrinkage, sulphate resistance, and ASR

17 SCM Replacement Level (%)
PLC Trial Pour at Gatineau Ready-Mixed Concrete Plant – Oct. 6, 2008 Objective: Field test performance of PLC concrete with various levels of SCM in an exterior flatwork application. Control sections with Type GU + SCM Eight Concrete Mixes: Cement SCM Replacement Level (%) 25 40 50 Type GU X Type GUL Cementing Materials: Type GU with 3.5% limestone (PC) Type GUL with 12% Limestone (PLC) Blended SCM = 2/3 Slag + 1/3 Fly Ash

18 PLC Trial Pour at Gatineau Ready-Mixed Concrete Plant – Oct. 6, 2008
Vibrating Screed Bullfloat Broom Finish Insulated Tarps (except slab 5)

19 Gatineau PLC Trial Pour – Cylinder Strengths

20 Close up photo taken here
April 2, 2009

21 PLC + 50% SCM PC + 50% SCM PLC + 25% SCM PC + 25% SCM

22 Concrete Pavement Performance
Concrete pavement constructed with PLC (20% limestone) at a Heidelberg cement plant. For the first 5 years, de-icing salts were applied to the surface of the concrete pavement. After 13 years the pavement surface was assessed both visually and with laboratory tests. The results show that: The surface was still undamaged by freeze-thaw. No changes in the concrete due to weathering or loading were observed. Concrete strength increased with age Since 1997 several bridge decks and highway paveement projects were completed with PLC in Europe. .

23 Quality limits on limestone in CSA A3000 (based on EN197)
4.4.4 Limestone addition to portland-limestone cement The limestone in portland-limestone cement shall meet the following requirements and shall be tested at least every 6 months: (a) The calcium carbonate (CaCO3) content calculated from the calcium oxide (CaO) content shall be at least 75% by mass. (b) The methylene blue value, an indication of clay content, determined by CSA A3004-D1, shall not exceed 1.2 g/100 g. (c) The total organic carbon (TOC) content, when tested in accordance with CSA A3004-D2, shall not exceed 0.5% by mass. These limits are only for limestone contents >5%

24 CSA A No Sulphate Resistant PLC No Blended PLC

25 CSA A23.1-09 Includes Concrete Made With Portland-limestone Cements (PLC)
(3) PLC shall not be used in a sulphate exposure environment

26 PLC Limitations of Use Concretes made with PLC CANNOT be used in sulphate exposure (even when combined with SCMs). This is due to concerns about mixed information in the literature, and to minimize any concern for Thaumasite sulphate attack. This issue is currently being addressed in three independent research programs. Early results are very encouraging.

27 PLC Production Issues As for all cements the performance of the product is strongly influenced by cement design and fineness (Blaine and sieve residue) Since limestone is typically easier to grind than clinker, production to constant Blaine fineness will result in coarser clinker and reduced performance. Therefore, in PLC, Blaines need to be higher Since strength requirements are to be the same as for Portland cement, each cement plant has to “optimize” the grinding of PLC Testing has shown that equivalent strength produces equivalent durability performance in concrete made with Portland-limestone cement.

28 Adoption Of PLC In Canada
2010 NBCC will reference PLC through reference to CSA A and CSA A Provincial jurisdictions will legislate its use when updating their Provincial Building Codes or when adopting the 2010 NBCC

29 SUMMARY PLC is not NEW. 10% GHG savings with PLC
In Canada all cement manufacturers will be optimizing PLC for equivalent strength with existing PC. Equivalent Concrete Strength = Equivalent durability Do not use PLC in sulphate environments. Testing is ongoing on this issue. Early results look promising. 2010 NBCC will reference PLC. Provincial Codes will reference PLC when updates are made, or when they adopt the 2010 NBCC

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