Notes

Slide Show

Outline

1	CALTRANS’ Use of SCM on the SFOBB Project By Tom Pyle, P.E. Office of Rigid Pavement and Structural Concrete Materials California Department of Transportation
2	What is SCM? Supplementary Cementitious Materials Advantages: Makes better concrete: Improves strength Decreases permeability Increases durability against ASR and sulfate attack Cost less than cement Environmentally friendly
3	Cement and SCMs
4	SCMs used in the SFOBB Fly ash: a left-over waste product from coal-fired electrical power plants. Slag: a left-over waste product from the manufacture of steel in a blast furnace.
5	Concrete structure
6	Piles of slag and fly ash at SFOBB project
7	San Francisco-Oakland Bay Bridge (SFOBB)
8	Project Limits
9	SFOBB East Span
10	Pier and Piles
11	Footings SCC: 50% slag Lightweight SCC: 60% fly ash 50% slag
12	Stockton pre-cast segments and panels (25% fly ash, W/C ~0.3)
13	Stockton 780-ton segments
14	452 Segments 28 Piers
15	Fly ash: by-product of coal power plant
16	Effect of fly ash on concrete strength
17	28-day compressive strength of pre-cast structures at SFOBB
18	Age effect on compressive strength of pre-cast structures at SFOBB
19	Compressive strength of pier table mix # 8430 (25% fly ash)
20	Effect of fly ash on permeability
21	Concrete with and without fly ash
22	Effect of slag on concrete strength
23	Compressive strength of bridge pier mix # 7504 (50% slag)
24	Iron production (by-product: slag )
25	Iron and slag separation
26	Slag granulator
27	Slag granulates
28	Slag granulate texture
29	Grinding process: Ball mills
30	Greenhouse gas (GHG) sources Main type of GHG: CO₂. Most greenhouse gasses stem (about 95%) from fossil fuel combustion. A large percentage comes from the manufacture of cement. ~ 7% worldwide. ~ 2% in the U.S.
31	Carbon dioxide emissions in 2002
32	Reduction of cement use by CALTRANS Caltrans’ goal: reduce the amount of cement by 50% when possible and yet have strong and long-lasting concrete. Means: replace cement with SCM. Consequence: Better concrete, GHG reduction and less waste products in landfills.
33	Projected California CO₂ emissions based on increased usage of SCM
34	Fly ash usage in 2004
35	Landfills
36	Slag cement usage in the U.S.
37	Final product using SCM: SFOBB
38	Conclusions At least 25% of SCM was used in the SFOBB: 25% in the pier tables 35% in the piles 50% in the pier columns 50 or 60% in the footings Advantages of using SCM include: Better concrete Doubly environmental benefits