BEYOND THE 50% SOLUTION?

Panelists Al Innis V.P. Quality & Product Performance Holcim (USA) Bruce Blair Vice President for Product Performance LaFarge Brian H. Green U.S. Army Corps of Engineers Prof. R. Doug Hooton Professor, Dept of Engineering, Univ of Toronto Jon Belkowitz President, Intelligent Concrete John Guynn (Moderator) Roman Cement

QUESTIONS TO BE EXPLORED Do we need the 50% solution (≥50% SCM substitution of Portland cement)? Is the 50% solution attainable for GU cement or only a luxury for highly engineered concrete? What are the technical hurdles impeding greater SCM usage? What are the economic (or psychological) hurdles impeding adoption?

POSSIBLE SOLUTIONS – BETTER OPTIMIZATION Do cement companies optimize Portland cement for SCM usage? Does intergrinding yield optimized results? Can it be better optimized and if so how? Is it worth the cost and effort? Are SCMs optimized for use with Portland cement? Does intergrinding yield optimized results? Can SCMs be better optimized and if so how? Is it worth the cost and effort?

2011 PUBLICATIONS FOR CEMENT-SCM OPTIMIZATION Common features of all four papers : Basic premise is that individually controlling the particle size distribution (PSD) of cement and SCM fractions yields more optimized blend PSD of at least one component is selected and individually controlled to enhance performance of another component not just itself Different than intergrinding (total PSD optimized) Different than micronizing the pozzolan (pozzolanic activity maximized)

NIST RESEARCH Gurney, L., et al. "Using Limestone to Reduce Set Retardation in High Volume Fly Ash Mixtures: Improving Constructability for Sustainability," Submission Date: 1 August Goal: Determine how PSD of supplemental limestone affects set time in HVFA cement (to offset retardation effect of fly ash) How accomplished: Used micronized and nano limestone of varying PSD and amount

CONCLUSIONS PSD of supplemental limestone can be engineered to offset the retardation effect of fly ash in HVFA cements PSD of limestone is controlled separately from that of Portland cement and fly ash (not interground) Finer PSD limestone (higher surface area) has greater acceleration effect PSD difficult to control if intergrinding Issue may be cost-to-benefit ratio

NIST RESEARCH (FOR ROMAN CEMENT, LLC) Bentz D., et al. "Optimization of cement and fly ash particle sizes to produce sustainable concretes," Cement & Concrete Composites 33 (2011) 824–831. Goal: Determine how independently varying the PSDs of cement and fly ash fractions affects strength and set time How accomplished: classified and reground Type I/II cement (Holcim) dedusted Class F fly ash Varied the concentration

Cement PSD

Fly Ash PSD

Plotted Strength Curve (not in publication)

CONCLUSIONS Early strength losses in HVFA cements can be offset by separately controlling the PSDs of Portland cement and fly ash fractions Coarser fly ash particles substantially offset increased water demand caused by finer cement Anecdotal evidence suggests Roman Cement blends can outperform interground blends at same substitution ratio Cannot individually control PSDs of cement and fly ash fractions if intergrinding Issue may be cost-to-benefit ratio

South China University of Technology Zhang, T., et al., “A new gap-graded particle size distribution and resulting consequences on properties of blended cement," Cement & Concrete Composites 33 (2011) 543–550. Goal: Determine how independently varying PSDs of cement and two different SCM fractions affects particle packing, water demand, and strength How accomplished: Independently classify cement and SCM fractions

GGBFS or Portland CementF Ash, Steel SlagSteel Slag, GGBFS, or Limestone

GGBFS or Portland F Ash, GGBFS, Steel Steel SlagCement Slag or Limestone

GGBFS PC FA or Slag Reference cement = Interground Blend of GGBFS = 36% PC = 25% F,BFS,SS, or L = 39%

Particle Packing Densities: BCB52.64 BCF50.17 BCS53.63 BCL SCS Portland Cement46.88 Interground Blend44.73

CONCLUSIONS Replacing fine and coarse Portland cement fractions with fine and coarse SCM fractions, respectively, and gap grading provides following benefits: Increased packing density compared to 100% Portland Cement and interground reference blend Comparable water demand as 100% PC; superior to interground reference blend Comparable strengths as 100% PC; far superior than interground reference blend Issue may be cost-to-benefit ratio

South China University of Technology Zhang, T., et al., “Study on optimization of hydration process of blended cement,“ Therm Anal Calorim DOI /s Goals: Study hydration behaviors of different particle size fractions of cement and various SCMs Also determine packing densities, water demand, and strength of blends

Particle Packing Densities: GGCFF55.62 GGCSS56.42 GGCGG56.37 CCCCC49.12 Interground Blend45.40

CONCLUSIONS Replacing fine and coarse Portland cement fractions with fine and coarse SCM fractions, respectively, provides following benefits: Increased packing density compared to 100% Portland Cement and interground reference blend Possibly reduced water demand compared to 100% Portland cement and Superior strength compared to interground reference blend Issue may be cost-to-benefit ratio

ADDITIONAL QUESTIONS What would it take for blended cements to attain market acceptance in the U.S.? Cost? Performance? Both? What about risk (or perceived risk)? Does it need to be a Disruptive Technology?

DISRUPTIVE TECHNOLOGY "Low-end disruption" occurs when the rate at which products improve exceeds the rate at which customers can adopt the new performance. At some point the performance of the product overshoots the needs of certain customer segments.  Powerful Incumbent

DISRUPTIVE TECHNOLOGY At this point, a disruptive technology may enter the market and provide a product which has lower performance than the incumbent but which exceeds the requirements of certain segments, thereby gaining a foothold in the market.

DISRUPTIVE TECHNOLOGY In low-end disruption, the disruptor is focused initially on serving the least profitable customer, who is happy with a good enough product. This type of customer is not willing to pay a premium for enhancements in product functionality.

DISRUPTIVE TECHNOLOGY Once the disruptor has gained a foot hold in this customer segment, it seeks to improve its profit margin. To get higher profit margins, the disruptor needs to enter the segment where the customer is willing to pay a little more for higher quality. To ensure this quality in its product, the disruptor needs to innovate.

DISRUPTIVE TECHNOLOGY The incumbent will not do much to retain its share in a not so profitable segment, and will move up-market and focus on its more attractive customers. After a number of such encounters, the incumbent is squeezed into smaller markets than it was previously serving.  Shrinking Incumbent Market Share Growing Distruptor Market Share 

DISRUPTIVE TECHNOLOGY And then finally the disruptive technology meets the demands of the most profitable segment and drives the established company out of the market.