Presentation on theme: "Portland-limestone Cement Presented by Derek Townson June 16 - BCRMCA Board of Directors' Meeting and Town Hall Meeting in Nanaimo, BC."— Presentation transcript:
Portland-limestone Cement Presented by Derek Townson June 16 - BCRMCA Board of Directors' Meeting and Town Hall Meeting in Nanaimo, BC
Portland-limestone Cement (PLC) Background on PLC Adoption Process in Canada PLC Concrete performance & durability tests 2
PLC IS NOT NEW Used successfully in Europe for over 25 years in a variety of applications and exposure conditions New Only To Canada 3
ASR and PLC 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
27/04/2015HGRS_Title Use of CEM II A-L 42.5 R in precast industry - Italy
27/04/2015HGRS_Title Use of CEM II A-L 42.5 R in precast industry - Germany
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 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 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
Cement types sold in Europe (according to Cembureau) PLC had the largest use in 2004 Most portland- composite cements contain limestone too!
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. CSA A
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. CAC Publication SN 3053
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
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.
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.
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.
Durability Tests carried out in Canadian PLC cements were produced in different grinding circuits by five cement companies: – Clinker contents with C 3 A 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/m 3
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
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 CementSCM Replacement Level (%) Type GUXXXX Type GULXXXX Eight Concrete Mixes: Type GU with 3.5% limestone (PC) Type GUL with 12% Limestone (PLC) Blended SCM = 2/3 Slag + 1/3 Fly Ash Cementing Materials:
PLC + 50% SCM PC + 50% SCM PLC + 25% SCM PC + 25% SCM
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..
Quality limits on limestone in CSA A3000 (based on EN197) 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 (CaCO 3 ) 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%
CSA A No Sulphate Resistant PLC No Blended PLC
CSA A Includes Concrete Made With Portland-limestone Cements (PLC) (3) PLC shall not be used in a sulphate exposure environment
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.
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.
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
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 NBCC will reference PLC. Provincial Codes will reference PLC when updates are made, or when they adopt the 2010 NBCC