CON 123Cementitious MaterialsSession 7Slag Cement
Ground Granulated Blast-Furnace Slag “Cement” (GGBFS) Ground Granulated blast-furnace slag is the correct technical term for slag that is finely ground and is used as a separately batched cementitious materials. Slag is ground to the fineness of Portland cement or finer.
Ground Granulated Blast-Furnace Slag “Cement”Finely Ground granulatedblast-furnace slagconsisting of primarilycalcium and aluminumsilicates, used as a partialreplacement for Portlandcement in concrete
ASTM 989 Slag Cement GGBFS – glassy granular material formed when molten blast-furnace slag is rapidly chilled as by immersion in water with or without compositional adjustments made while the blast-furnace is molten
Grades of Slag - ASTM C 989 Strength of 1:1 Slag: Cement MortarSlag Activity Index = Strength of Control Cement Mortar Grade 7-day Index 28-day Index 80 - 75 100 75 95 120 95 115 Requirements for average of 5 consecutive
Specifications and Grade of Ground Granulated Iron Blast-Furnace Slags ASTM C 989 (AASHTO M 302) Grade 80 Slag with a low activity index Grade 100 Slag with a moderate activity index Grade 120 Slag with a high activity index
Slag - Manufacture Iron Blast Furnace Iron ore is layered with a mixture of limestone and coal or coke. The coal is the fuel. The limestone is a flux that reduces fusion temperatures. The molten materials settle out at the bottom and slag floats on the top of the pig iron. It is tapped away
Slag - Manufacture Iron Blast FurnaceIron Ore Limestone/CoalFusion at1400 to 1600 C Slag Pig Iron
Slag – Manufacture Hot Runner Molten blast furnace slag is tapped from the blast furnace, moved through a hot runner on the blast-furnace work floor. Dropped in a “blow” box to a jet-process granulator. GGBF is glassy - with the right chemistry and morphology to form hydraulic cement when finely ground.
Slag - Typical DosageApplication Dosage ( % by wt)Exterior flatwork 35%General use 35 to 50%Mass Concrete 60 to 80%Sulfate Resistance Type II equivalent 35% Type V equivalent 50%Marine/chemical/heat >50% < 80%
Slag – Typical Dosage Application Dosage (% by wt)Exterior Flatwork 35%General Use 35 to 50%Mass Concrete 60 to 80%Sulfate Resistance Type II Equivalent 35% Type V Equivalent 50%Marine/chemical/heat >50%, <80%
Slag - Mixture Proportioning Typical - 35 to 50% wt. cementitious w/c ratio w/(cement + slag) ratio Water demand - 1 to 5% lower Admixture dosage Similar for air entraining admixtures May be lower for others SG 2.90 - more abs. vol. than cement
Slag BenefitsWorkability Finishability Pumpability Color Durability Strength
Slag Cement and the Environment Recovered/ recycled material Replaces Portland cement Reduction of CO2 Reduction of Heat Reduced Material extraction Energy Saving Lighter Color
LEED Credits Leadership in Energy and Environmental Design (LEED) is a system developed by the United States Green Building Council to rate a buildings environmental performance. This system has become the principal method by which buildings can achieve green building certification. The system is based on credits earned in five major categories. Slag cement can positively impact several credit categories
LEED Categories Site credit for reduction of heat islands: Use of high-albedomaterials like concreteproduced with slag cement. Materials credit for building reuse: Slag cement makesconcrete structures moredurable. Materials credit for recycled content: Slag cement is arecycled material used inconcrete. Materials credit for use of local/regional materials: Slagcement can be considereda local material in many areas.For more information on the LEED system, visit www.usgbc.org
LEED Categories Site credit for reduction of heat islands: Use of high-albedo materials like concrete produced with slag cement. Materials credit for building reuse: Slag cement makes concrete structures more durable. Materials credit for recycled content: Slag cement is a recycled material used in concrete. Materials credit for use of local/regional materials: Slag cement can be considered a local material in many areas. For more information on the LEED system, visit www.usgbc.org.