Portland-limestone CementPresented 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

19/04/23 HGRS_Title

Use of CEM II A-L 42.5 R in precast industry - Italy

19/04/23 HGRS_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.• 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 197-1 allows 5% MAC (Typ. Limestone) in all 27

common cements, as was commonly practiced in various European cement standards prior to that.

• 2000 EN 197-1 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 4.3.1.(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 A3000-08

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 CanadaStep 1Step 1May 2007 Literature Review: General SummaryMay 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 May 2007 Literature Review: General CommentsComments

• 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 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

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 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

Cement SCM Replacement Level (%)

0 25 40 50

Type GU X X X X

Type GUL X X X X

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 Trial Pour at Gatineau Ready-Mixed Concrete Plant – Oct. 6, 2008 PLC Trial Pour at Gatineau Ready-Mixed Concrete Plant – Oct. 6, 2008

Vibrating Screed Bullfloat

Broom Finish Insulated Tarps (except slab 5)

Gatineau PLC Trial Pour – Cylinder StrengthsGatineau PLC Trial Pour – Cylinder Strengths

24.221.7

18.915.3

25.2

20.7 19.215.6

0

10

20

30

0% SCM 25% SCM 40% SCM 50% SCM

Str

engt

h (M

Pa)

3-Day Strength PC

PLC

30.2 29.8 30.3 29.430.5 29.6 31.128.8

0

10

20

30

40

0% SCM 25% SCM 40% SCM 50% SCM

Str

engt

h (M

Pa)

7-Day Strength

37.741.3

43.5 43.0

38.2 39.843.5 42.5

0

10

20

30

40

50

0% SCM 25% SCM 40% SCM 50% SCM

Str

engt

h (M

Pa)

28-Day Strength

41.345.4

48.6 48.7

40.944.7

48.346.5

0

10

20

30

40

50

60

0% SCM 25% SCM 40% SCM 50% SCM

Str

engt

h (M

Pa)

56-Day StrengthPC

PLC

April 2, 2009

Close up photo taken here

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)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%

CSA A3001-08

No Sulphate Resistant PLCNo Blended PLC

CSA A23.1-09 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 A3000-09 and CSA A23.1-09

• 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.

• 2010 NBCC will reference PLC. Provincial Codes will reference PLC when updates are made, or when they adopt the 2010 NBCC