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 PLCAdoption Process in CanadaPLC Concrete performance & durability testsThere 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, andResults of Canadian durability testing of PLC concrete.
3 PLC IS NOT NEWUsed successfully in Europe for over 25 years in a variety of applications and exposure conditionsNew Only To CanadaThe 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 lengthFastest way to pass through the alpsCement used:CEM III: concrete in contact with high sulfated waterCEM II/A-D 52,5: shotcrete and precastCEM II-A- L: concrete for pavingHere 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.13/04/2017HGRS_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 Germany13/04/2017HGRS_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) cement1990, 15+/-5% limestone blended cements being used in Germany1992, in UK, BS 7583 allows up to 20% in Limestone Cement2000 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 GU2004 ASTM C 150 allows 5% in Types I-V2007 AASHTO M85 allows 5% in Types I-VThis 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 2004This 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 1Initially 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 SummaryAdvantages: 10% GHG Emissions Reduction.Uncertainty: Carbonation, Sulphate exposure and Potential for ThaumasiteUnknown – 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 2Various 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 3The 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 durabilityDue 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 performedConcrete made with w/cm ratios 0.35 to 0.8Cement content 225 kg/m3 to 420 kg/m3
16 Concrete Tests carried out with Canadian materials Concrete tests with:10% to 15% PLCSlag (15, 25, 30%, 50%) and fly ash 25%Slump, slump retention and air were measuredDurability 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, 2008Objective:Field test performance of PLC concrete with various levels of SCM in an exterior flatwork application.Control sections with Type GU + SCMEight Concrete Mixes:CementSCM Replacement Level (%)254050Type GUXType GULCementing 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 ScreedBullfloatBroom FinishInsulated Tarps (except slab 5)
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 ageSince 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 cementThe 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%
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 UseConcretes 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 IssuesAs 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 higherSince strength requirements are to be the same as for Portland cement, each cement plant has to “optimize” the grinding of PLCTesting 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 AProvincial 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 durabilityDo 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