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Slag Cement: Helping Concrete Perform Better
- 1. Jan R. Prusinski, PE Vice President of Marketing Skyway Cement Company Nebraska Concrete Paving Association 40th Annual Meeting January 22, 2019
- 2. Eagle Materials Cement Central Plains Cement Mountain Cement Nevada Cement Illinois Cement Fairborn Cement Skyway Cement Concrete and Aggregates Wallboard Proppants (Frac Sand) PortlandCementSlag Cement
- 3. Non-metallic product of an iron blast furnace Granulated Ground Cementitious material Hydraulic cement Granules Slag Cement
- 5. Slag Diverted to granulator; quenched with high pressure water (6 - 10 tons water/ton slag) Molten slag floating on top of molten iron
- 6. Slag granule dewatering Slag granules Slag granule stockpiling
- 13. Roman cements and concrete Aspdin patents portland cement Slag cement produced as a separate material ... 300-500 BC 1824 1950’s 2000’s Sparrow’s Point starts widespread use in Eastern U.S. Loriot makes slag- lime mortar 1774 1890’s First slag- portland blended cements 1982 Rapid expansion throughout U.S.
- 14. 3648 3110 0 500 1000 1500 2000 2500 3000 3500 4000 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017-F tons(000's) • Slag cement market share (compared to portland) has grown by 80% since 2000 • Slag Cement Association expects consumption to grow 3-5% over the next 5 years • SCA’s Western Region (including Nebraska) grew by 23% in 2017 2017 U.S. portland cement consumption: 96.8 M tons
- 16. Slag Cement + Water + Calcium Hydroxide From Portland Cement More Calcium- Silicate Hydrate Slag Cement + Water Calcium-Silicate Hydrate • Higher strength • Lower permeability • Greater durability
- 17. Portland Cement Concrete System Portland-Slag Concrete System Aggregate Portland Cement Slag Cement AggregateVoids Calcium Silicate Hydrate
- 19. Attribute Portland Cement Slag Cement Fly Ash Origin Limestone, Clay, etc. Iron blast- furnace slag granules Coal-fired electric power plant byproduct Production Manufactured product Manufactured product Byproduct Classification Hydraulic cement Hydraulic cement Pozzolan Typical Replacement Rates -- 25-50% (80% in mass conc.) 15-30% (50% in mass conc.) 2017 Use in Concrete 96.8 M tons 3.1 M tons 14.1 M tons
- 20. Constituent Portland Cement Slag Cement Class C Fly Ash Class F Fly Ash CaO 65 45 25 3 SiO2 20 33 37 58 Al2O3 4 10 16 20 Fe2O3 3 1 7 10 MgO 3 6 7 1
- 22. A 50% cement / 50% slag cement is compared to 100% Reference cement at the various ages. The reference cement used helps determine the grade of slag cement (Alkalies: 0.60 – 0.90% & 5,000 psi @ 28 days). The ASTM C989 spec allows for use of a “standard” reference cement.
- 25. Reduced water demand Better slump retention Enhanced workability Easier consolidation Improved pumpability Superior finishability Consistent air content • Particles are dense and smooth • Little water is absorbed during initial mixing
- 26. 0 2 4 6 8 10 300 320 340 360 Water Content (lb/cy) Slump(in) 100%Portland 50%Slag Cement
- 27. Slag Cement Mixes Set Slower in Colder Temperatures Accelerators Can Speed Up Set Times Faster than 100% Portland Cement Mixes Not Much Difference in Set Times at Higher Temperatures (+90oF) Decreasing the w/cm with MRWR and HRWR will speed up the set time Use T-III + Slag cement
- 28. Improved Compressive and Flexural Strengths Reduced Permeability Improved Corrosion Resistance Increased Resistance to Sulfate Attack and Alkali- Silica Reaction Reduced Heat Generation • Particles are dense and smooth • Little water is absorbed during initial mixing
- 29. Higher 28-day compressive strengths ◦ 1,000-2,000 psi higher Lower early strengths Typically matches portland strengths ~7 days Optimum strength replacement ~35% 0 2,000 4,000 6,000 8,000 10,000 7 Day 28 Day Comp.Strength,psi 100% Portland 25% Slag 50% Slag 0 200 400 600 800 1,000 1,200 7 Day 28 Day FlexuralStrength,psi 100% Portland* 50% Slag**
- 30. 0 20 40 60 80 100 120 140 0 7 14 21 28 StrengthasPercentofTypeI at28days Age, days Type I Type IS(25)+15C Type IS(25)+15F Nominal Properties w/cm = 0.45 565 lbs/cu.yd. cementitious material slump 4” air content 6.5% Type I strength at 28 days = 6120 psi (42 MPa)
- 31. For concrete exposed to deicing chemicals: ◦ Use good finishing practices (no premature finishing) ◦ Appropriate, timely curing essential ◦ Adequate air entrainment 4.5% to 7.5% air ◦ W/Cm ≤ 0.45 ◦ Compressive strength ≥ 4,500 psi Any concrete will be susceptible to deicer scaling if the surface is not finished and cured properly
- 35. SCM Used % Portland Replacement Average 14- day expansion % Expansion < 0.10? Class F Fly Ash 20% 0.1250 No Slag Cement 25% 0.1197 No Slag Cement 35% 0.0830 Yes Buno Road, Michigan
- 36. Reconstructed 7 miles of 8-lane freeway, 6 interchanges w on/off ramps 37 bridges rehabilitated or replaced Slag cement used at over 30% to mitigate potential ASR and achieve specified flexural and compressive strengths Lighter color enhances night time visibility Consistent, reliable performance contributed to completion of project ahead of schedule
- 37. Slag cement can mitigate sulfate attack in concrete by: ◦ Decreasing the total C3A in the system ◦ Decreasing the permeability of the concrete which prevents the ingress of sulfates into the concrete ◦ Reacting with calcium hydroxide to form CSH Proper addition can: ◦ Type I+S => TII or TV ◦ Type II+S=> TV 50% slag in Na2SO4 OPC in water OPC in Na2SO4 OPC in MgSO4 OPC in K2SO4
- 40. 0.00 0.03 0.05 0.08 0.10 0 50 100 150 200 Expansion(percent) Days Type I Type II 20% Slag* 35% Slag* 50% Slag* Moderate Sulfate Resistance (6 months) High Sulfate Resistance (6 months) *With Type I Portland cement
- 41. Denser hydrated cementitious structure Reduced porosity Decreased permeability Greater durability
- 42. Item Original Final Portland Cement 658 lbs/yd3 306 lbs/yd3 Slag Cement 305 lbs/yd3 Fly Ash 282 lbs/yd3 Silica Fume 94 lbs/yd3 Coarse Aggregate - 1900 lbs/yd3 Fine Aggregate - 1176 lbs/yd3 Water - 28.5 gals/yd3 Admixture - 6 oz/cwt Air Entraining Agent - 0.6 oz/cwt Field Results Total cementitious reduced from 940 to 611 lb/cy 28-day compressive strength: 5,350 to 5,590 psi 56-day chloride permeability: 824 to 1,110 coulombs
- 43. Slag cement makes whiter concrete More reflective Improved safety Has been used to replace partially/fully white cement for some applications Portland Cement Slag Cement 0.540.53 0.50 0.62 0.46 0.6 0.64 0.69 0.63 0.20 0.30 0.40 0.50 0.60 0.70 Portland Fly Ash Slag Cement Slag + White Portland White Portland SolarReflectance
- 44. Slower set time in colder temperatures Lower early strengths precast, pipe, masonry accelerated curing Potential deicer salt scaling at higher replacements (+25%) due to slower set times and slower bleeding Additional silo space (blended cement can help) Greening – goes away over time (oxidizes)
- 45. • Rehab asphalt runway with 18” concrete pavement overlay • Runway extended by 700’ and widened by 50’ to provide 12,700 ft by 200 ft new runway • Concrete Specifications • 700 psi min 28-day flexural • 550 lb/cy max cementitious • Mixture • ASTM C595 Type IS (40) slag blended cement • 4-aggregate mixture yielded • 1,300 psi flexural strength at 28-days • Improved strength, durability and smoothness
- 46. Concrete mixture with 40% slag cement 2015-2018 Average flex strength > 900 psi
- 47. Cement/Slag Cement 50/50 40/60 Cement (lbs) 282 226 Slag Cement (lbs) 282 338 Total Cementitious (lbs) 564 564 Sack Content 6 6 Coarse Aggregate (lbs) 1920 1920 Fine Aggregate (lbs) 1260 1260 Water (gals) 34 34 Air (oz/cwt) 6 6 WRDA (oz/cwt) 3 3 Slump (inches) 5 5 Air Content (%) 4 - 6 4 - 6 7 Day (psi) 2220 2600 28 Day (psi) 4560 4740 56 Day (psi) 4740 5250 0 1000 2000 3000 4000 5000 6000 7 Day (psi) 28 Day (psi) 56 Day (psi) Strength(psi) Age (Days) 50/50 40/60
- 50. 30% slag cement Built 2004 Project engineer: HWS Finishers: excellent workability at low w/cm and low slump
- 51. 13,000 cy Gehring Construction and Ready Mix Colorado Structures Parking lot And city street around Walmart
- 52. 20-35%, with some C Ash (2004) East Granville St. Memorial Park Dr. 47 B Mixtures 28 Day 56 Day 20% Slag 5,522 6,112 30% Slag 5,708 6,165 35% Slag 5,837 6,272 30/20 Slag/C Ash 5,896 6,691
- 53. Jan R. Prusinski, PE ◦ 832-265-7130 cell ◦ Jprusinski@skywaycement.com Joel Sedlacek ◦ 402-305-3709 ◦ jsedlacek@centralplainscement.com Megan Dangel ◦ 918-896-0598 ◦ mdangel@centralplainscement.com