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Item _1___Date: To: From: Subject: 8 September 2011 ASTM Committee C01 and Subcommittee C01.10 Paul Tennis, Chairman C01.10 WK33157: Proposal to Revise ASTM C595, Provisions for Type IL Cements

RationaleOverview This proposal defines a new type of C595 blended cement containing between 5% and 15% limestone as an ingredient. The motivation for this proposal is to provide a means of implementing proven cement technology to improve sustainability of concrete while maintaining desired performance. The proposed Type IL cements can be produced with a lower environmental footprint while permitting concrete with similar performance to existing blended cements in a wide variety of applications. Such cements have been used in Europe for decades as well as other countries around the world, and in 2008 Canada adopted provisions for portland-limestone cement containing between 5% and 15% limestone in CSA A3001. The discussion and example data below are mainly extracted from State-of-the-Art-Report on Use of Limestone in Cements at Levels of up to 15% (Tennis, Thomas and Weiss 2011) and The Durability of Concrete Produced with Portland-Limestone Cement: Canadian Studies (Thomas and Hooton 2010), both of which may be downloaded at the links provided (see References Cited) or upon request to the C01.10 chairman, Additional data and information on effects of use of limestone on fresh and hardened concrete properties, as well as several case studies on use of cements with limestone in the US and Canada are included in those reports. This change has been developed by Task Group C01.10.05 (Joint AASHTO-ASTM Harmonization Task Group, JAAHTG) and parallel changes to AASHTO M240 will be balloted to AASHTO TS3a. The approach taken by the JAAHTG in developing provisions has been to review how Canadian and European standards address issues, but to also investigate the basis for specific provisions and consider potential improvements. A similar item was balloted on Subcommittee Ballot C01.10 (2011-01). It received a persuasive negative and was withdrawn and revised to address the issue raised (regarding significance and use statements in the proposed annexes), as well as other points raised in that ballot. This item is being considered concurrently. Specific Changes under Ballot This ballot item is based on ASTM C595-11. Pages 1 through 9 of this ballot include the rationale and supporting information. Specific changes to the standard are shown beginning on page 10. Proposed additions are underlined and proposed deletions are shown in strikethrough font. Only changes so indicated are being balloted. Other text is provided for information only. Notes, footnotes, tables, and

referenced documents will be renumbered or updated editorially, if needed. Dates in Section A2.6 and A3.6 will be inserted by the ASTM Editor and will be 5 years after date of publication of the standard, per ASTMs Form and Style Manual Section A21. Primary proposed changes include: 1. Revisions to Sections 1.1 (scope), 4.1.1.3, 4.2.2, Notes 2 and 5, Sections 6.3, 6.12 and 6.13 (revised to 6.13 and 6.14), new Sections 6.19 and 6.20. These changes generally define portland-limestone blended cements as cements with more than 5.0% and up to and including 15.0% limestone content. 2. New Section 7.2 and new Table 5 with requirements for limestone to be used as an ingredient in blended cements. 3. Changes to Tables 1 and 2 to define requirements for portland-limestone blended cements. 4. New Annexes A2 on the methylene blue index test and A3 on total organic carbon content. These provide procedures for use in qualifying limestone as an ingredient. A procedure for checking conformance of a limestone with the methylene blue requirements with a single iteration is proposed as Appendix X1. These test procedures are those used in CSA A3000. Other changes (for examples, Sections 10, 14, 15, and 17) proposed throughout are for consistency and clarity. Detailed discussion Range of Limestone Content in Proposal Cements with between 5% and 15% by mass limestone are proposed as a new type of blended cement. A maximum value of 15% was chosen based in part on experience in Europe and Canada, which demonstrates that equivalent performance can be achieved with limestone contents in this range. Above this range, some loss of performance (for example strength) is commonly observed, although still useful for a wide array of applications. European cement standard EN197-1 permits limestone contents up to 35% to be used. Mechanisms affecting the performance of limestone in cement include more easily ground limestone filling in pores between larger cement grains and possibly some small amount of chemical reaction of the limestone. Relative compressive strength data for one base cement with a range of limestone content is provided in Figure 1 and shows increases in strength (relative to a control without limestone) until about 15% limestone, after which strength decreases relative to the control.

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Figure 1. A correlation between estimated porosity and measured strength development with limestone for a single base cement (Matschei et al. 2007). The relative strength for this cement with limestone is higher than the control until about 15% by mass limestone.

Environmental Benefits The primary sustainability effect of using limestone as an ingredient in portland-limestone blended cements at levels of 5% to 15% by mass is that less clinker has to be produced for an equivalent amount of cement, and therefore less energy is consumed and CO2 emissions (and other greenhouse gases) are reduced. Carbon dioxide emissions for cement plants come predominantly from two sources: calcination of the limestone, a primary raw ingredient for clinker manufacture, and fossil fuel consumption to heat the raw materials to the temperature required to form clinker. Very roughly, limestone is about 50% by mass CO2 and release of this CO2 during calcination accounts for about 60% of the CO2 emissions produced at a cement plant. Both of these quantities are reduced in blended cement production as less clinker is used in the cement. These reductions are roughly proportional to the decrease in the amount of clinker in the blended cement. Figure 2 provides specific examples for CO2 emission reductions for three German cement plants (Schmidt 1992). The calculations include the total energy demand of all steps in the production process taking into account the specific demand of fuel energy. The replacement of about 15% by mass of the clinker by limestone reduces CO2 emissions on average by 12% (Schmidt et al. 2010). Similar results can be calculated for the emissions of nitrous oxides (NOx) and sulfur dioxide (SO2). An analysis of the environmental impact of up to 5% limestone in the production of portland cement is found in Nisbet (1996). Based on the approach used in that analysis, an estimate is given in Table 1 assuming 10% or 15% limestone for portland-limestone cements. These provide conservative estimates of reductions in environmental and energy impacts that can be achieved through use of limestone, as compared to a portland cement without limestone. It should be noted that portland cements in the US are permitted to contain up to 5% limestone (typical level is likely about 3% on average), which will reduce the savings noted in Table 1. Even if the maximum amount of limestone (5%) is used in portland cements, use of portland-limestone cements with a total of 10% to 15% limestone will result in significant additional reductions in energy and emissions.

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Portland cement

1.0Portland-limestone cement

0.8kg CO2/kg cement

0.6

0.4

0.2

0.0

Plant 1

Plant 2

Plant 3

Figure 2. Specific CO2 emissions from the production of portland cement or portland-limestone cement for 3 German cement plants (adapted from Schmidt 1992).

Estimated Annual Reduction in Energy Usage and Emissions Resulting From Use of 10% or 15% Limestone in Blended Cement* 10% limestone 15% limestone (per million tons of (per million tons of cement) cement) Energy Reduction Fuel (million BTU) 443,000 664,000 Electricity (kWh) 6,970,000 10,440,000 Emissions Reduction SO2 (lbs) 581,000 870,000 NOX (lbs) 580,000 870,000 CO (lbs) 104,000 155,000 CO2 (tons) 189,000 283,000 Total Hydrocarbon, THC (lbs) 14,300 21,400 * Following the approach of Nisbet (1996). Estimates compare portland cement with 5% gypsum, no limestone, and no inorganic processing addition with blended cement containing portland cement clinker, gypsum and the amount of limestone indicated.

Table 1.

Cement Requirements The ballot proposes changes to define portland-limestone blended cements. These cements meet the same physical requirements as other C595 cement types: Identical requirements for minimum compressive strengths, autoclave expansion (soundness) testing, initial setting time, and air content would apply to portland-limestone cement Type IL and to Type IT cements containing limestone as apply to cement Types IP, IS(