Decreasing the Clinker Component in Cementing Materials: Performance of C ti M t i l P f f Portland-Limestone Cements in Concrete in Combination with Supplementary in Combination with Supplementary Cementing Materials Doug Hooton, Amir Ramezanianpour UNIVERSITY OF TORONTO DEPARTMENT OF CIVIL ENGINEERING DEPARTMENT OF CIVIL ENGINEERING 2010 International Concrete Sustainability Conference, Dubai, UAE 1
Why Portland-Limestone Cements (PLC)? Cements (PLC)? • Portland Cement manufacturing g produces CO 2 – Limestone decomposition – Fuel consumption • Governments are preparing cap p p g p and trade limits on point source CO 2 emissions • Not new since PLC (CEM IIA-L) Not new since PLC (CEM IIA L) has been in use in Europe for > 20 years and is now the most widely used cement type 2010 International Concrete Sustainability Conference, Dubai, UAE 2
PLC in Canadian Standards • In 2008, a new class of Portland-Limestone cements was added to the cement standard CSA A3001 with up to added to the cement standard, CSA A3001, with up to 15% blended or interground limestone replacing cement clinker. • The CO 2 emissions from PLC are ~10% less relative to CSA Type GU (~ASTM Type I) Portland cement. • In addition, fewer raw materials and less energy are used to produce PLC used to produce PLC. • When properly optimized, the limestone is not inert and contributes to the properties of the cement. p p • PLC have to meet the same set time and strength development performance as portland cement of the same type (eg. GU ---same as ASTM Type I) 2010 International Concrete Sustainability Conference, Dubai, UAE 3
Portland-Limestone Cements in Canadian Standards in Canadian Standards • Changes to the CSA Changes to the CSA A3000 Cementitious Materials standard in 2008 and to the A23.1 Concrete standard in 2009 allow use of PLC • The National Building The National Building Code of Canada was updated in 2010 to include these changes g 2010 International Concrete Sustainability Conference, Dubai, UAE 4
More Sustainable Cementing Materials Cementing Materials SCMs (and blended cements) Portland Blended Portland- cement hydraulic limestone type cement cement PLC type type GU GUb GUL (GULb) 2010 International Concrete Sustainability Conference, Dubai, UAE 5
CSA A23.1 Types of Hydraulic Cements Portland Portland Blended hydraulic Blended hydraulic Portland-limestone Portland limestone Name Name cement cement cement *** General use GU GUb GUL cement Moderate MS MSb - sulphate-resistant cement Moderate heat of MH MHb MHL hydration cement High early- HE HEb HEL strength cement strength cement Low heat of LH LHb LHL hydration cement High sulphate- HS HS HSb HSb - resistant cement *** Portland-limestone cements shall not be used in sulphate exposures as defined in Table 3 of CAN/CSA-A23.1 (even when mixed with SCMs) 2010 International Concrete Sustainability Conference, Dubai, UAE 6
PLC in Sulfate Exposures p • Currently PLC is not allowed in sulfate exposures b th by the CSA A23.1 concrete standard due to CSA A23 1 t t d d d t concern with potential for thaumasite sulfate attack (TSA) at cool temperatures (5-10 o C). • However, in 2010, the CSA A3001 cement standard was revised to allow PLC blended cements in sulfate exposures cements in sulfate exposures • Research is ongoing to develop sufficient data to revise the A23.1 concrete standard to allow PLC + SCM (or blended cements) in sulfate exposures. 2010 International Concrete Sustainability Conference, Dubai, UAE 7
Thaumasite Thaumasite Form Form of of Sulfate Sulfate Attack Attack 30-year-old bridge column exposed to wet oxidized sulfide clay in to wet oxidized sulfide clay in England Thaumasite is not so common, but when it occurs, it attacks the whole when it occurs it attacks the whole matrix. Photos from UK Expert Panel 2010 International Concrete Sustainability Conference, Dubai, UAE 8
New Test for Evaluating Mitigation of Thaumasite Sulfate Attack f Th it S lf t Att k • A new test method, based on ASTM C1012, but with mortar bars stored in sulfate solution at 5 o C with mortar bars stored in sulfate solution at 5 C, was standardized by CSA in 2010 • In this new test, PLCs were found to show potential to form thaumasite, if used as the sole t ti l t f th it if d th l binder. • But when sufficient levels of slag fly ash But when sufficient levels of slag, fly ash, metakaolin, and silica fume (ternary) binders were used, no thaumasite formed. • This was the basis for CSA A3001 being revised Thi th b i f CSA A3001 b i i d in 2010, allowing blended cements with limestone 2010 International Concrete Sustainability Conference, Dubai, UAE 9
ASTM and PLC • At least 2 producers in the USA are making p g 10% limestone cements under ASTM C1157 and have used them in both structures and pavements. • ASTM C595 may be amended in 2011 to allow for PLC blended cements. • In support of ASTM activities, Thomas & H Hooton prepared a report: PCA R&D SN3142, t d t PCA R&D SN3142 The Durability of Concrete Produced with Portland-Limestone Cement: Canadian Studies Studies. 2010 International Concrete Sustainability Conference, Dubai, UAE 10
A3001 PLC Performance Requirements Requirements • In CSA A3000, the setting times and strength , g g development limits are the same for PLC as for portland cements. • Heat of hydration limits are also the same for y MH and LH cements. • In concrete, PLC also performs well with slag or fly ash at normal replacement levels. • Mechanisms: Carbo-aluminate hydrates form and also fine carbonates provide nucleation sites that accelerate hydration 2010 International Concrete Sustainability Conference, Dubai, UAE 11
Cement types sold in Europe 1999 - 2004 (according to Cembureau data) ( g ) 1.7 1.8 100 2.1 2.1 2.2 Others 1.9 6.1 1.5 1.8 3.4 2.9 5 5.7 CEM V - Composite Cement 3.2 5.0 5.4 9.5 90 4.0 CEM IV - Pozzolanic 6.5 5.6 5.5 5.1 4 8 4.8 5 6 5.6 CEM III - Blast furnace slag 80 12.5 CEM II - Portland-composite 14.5 14.3 9.6 16.8 16.8 CEM II - Portland-limestone 70 pe (%) CEM II - Portland-fly ash CEM II - Portland-pozzolana nt Types in Europ 24 0 24.0 60 18.9 24.6 24.5 CEM II - Portland-slag 15.0 31.4 CEM I - Portland 50 5.4 6.2 7.0 PLC had the 5.7 3.7 6.9 2.9 2.7 2.1 40 1.2 1.2 4 8 4.8 7 4 7.4 5.4 5 4 Cemen 4.2 largest use 6.8 5.9 1.4 4.5 30 in 2004 20 35.4 34.2 33.7 Most portland- p 32.1 31.6 27 5 27.5 composite 10 cements contain 0 1999 2000 2001 2002 2003 2004 limestone too 2010 International Concrete Sustainability Conference, Dubai, UAE 12
Why PLC works: (Herfort, 2008) Limestone and cement aluminates form Carboaluminates, which fill in porosity and increase strength + if get more aluminates from SCM optimum will shift to higher % limestone aluminates from SCM, optimum will shift to higher % limestone 15 compressive strength measured nd 10 10 ] strength [%] of porosity a 5 increase 0 0 compressive ive change o decrease -5 c relati -10 10 total porosity calculated -15 0 2 4 6 8 10 12 14 16 18 20 22 amount of CaCO 3 added [wt.-%] Equal strength at 0 and 13% PLC 2010 International Concrete Sustainability Conference, Dubai, UAE 13
PLC + Slag, Fly Ash, or Metakaolin 15 compressive strength measured nd 10 10 f porosity an strength [%] 5 increase ompressive s ve change of 0 decrease -5 co relativ -10 total porosity calculated -15 0 2 4 6 8 10 12 14 16 18 20 22 amount of CaCO 3 added [wt.-%] Research is currently underway at U of Toronto to confirm 2010 International Concrete Sustainability Conference, Dubai, UAE 14
Limestone Fineness 100% D50 (Limestone): 7 to 10 μ m 50% D50 (clinker): 15 μ m 0 1 μ m 10 μ m 100 μ m Limestone fineness in the interground product is significantly finer than the clinker fraction L. Barcelo, Lafarge 2010 International Concrete Sustainability Conference, Dubai, UAE 15
Lab Concrete Data • Before balloted by CSA A23 1 all of • Before balloted by CSA A23.1, all of the Cement companies and several universities performed extensive p testing for fresh, hardened, and durability properties on PLC and together with SCMs normally used. t th ith SCM ll d • A couple of examples follow. 2010 International Concrete Sustainability Conference, Dubai, UAE 16
Initial concrete test results – straight [MPa] cement (and limestone) 40 30 20 10 0 60 1d 3d 7d 28d 56d GU P LC 10 P LC 15 40 20 0 w/c 0.70 1d 3d 7d 28d 56d 91d 60 GU P LC 10 P LC 15 40 40 GU 20 w/c 0.40 PLC10 0 1d 3d 7d 28d 56d 91d GU P LC 10 P LC 15 PLC15 w/c 0.37 2010 International Concrete Sustainability Conference, Dubai, UAE 17
Initial concrete test results – with [MPa] 30% Slag 40 40 30 20 10 10 0 60 1d 3d 7d 28d 56d GU P LC 10 P LC 15 40 w/cm 0.70 20 0 60 1d 3d 7d 28d 56d 91d GU GU P P LC10 LC 10 P P LC 15 LC15 40 40 GU w/cm 0.40 20 PLC10 0 1d 3d 7d 28d 56d 91d GU P LC 10 P LC 15 PLC15 w/cm 0.37 2010 International Concrete Sustainability Conference, Dubai, UAE 18
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