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San Francisco-Oakland Bay Bridge Seismic Safety ProjectsSkywayCE 165Concrete Construction& TechnologyGroup Members:Jessica ArianiHendra Raharja IkhwanInez Cynora Kuswara KoeWing Shun (Welson) Kwan• Oakland to San Fransisco• 270,000 vehicles per dayIntroductionThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Seismic issue– Loma Prieta earthquake Æ knocking down a portion of upper deck– Major earthquake in the next 30 years• Cheaper and safer than retrofitting the old bridge• Traffic issueWhy New Bay BridgeThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• West Approach• West Span• Yerba Buena/Treasure Island•SAS• Skyway• Oakland TouchdownProject Break DownThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsIntroductionThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Supplier: CEMEX– Davenport at Santa Cruz• Raw material• Fineness: 345 m2/gm (test result) > 280 m2/gm (ASTM C 150 specifications )CementCalcium Oxide (CaO) 65.5%,Silicon Dioxide (SiO2) 21.2%Aluminum Oxide (Al2O3)4%Ferric Oxide (Fe2O3) 4.2%The San Francisco-Oakland Bay Bridge Seismic Safety Projects• Type II cement is used– High early strengthCementCompoundNew Bay Bridge Cement Compound composition (%) Typical Type IICompound Composition (%)C3S 6730C2S 1046C3A 45C4AF 1313The San Francisco-Oakland Bay Bridge Seismic Safety Projects• w/cm ratio various Section w/c ratio Strength (psi) PurposeSegment 0.30 5.0 x 106Strong Light Weight 0.45 3.5 x 106LightPier Column 0.49 3500 FlexiblePile 0.39 ‐ DurablePier Table 0.32 ‐ FlexibleCementThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Important in the new Bay Bridge construction • Contributes in strengthAggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsAggregates for the project:• 80% are imported from Canada • others are from Bay Area location AggregateThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Hanson Company buys Canadian aggregates from Pacific’s Construction Aggregates Ltd.-Sechelt • The aggregates are shipped from British Columbia to Redwood City once in two weeks• The aggregates are transported from Redwood City to the job site daily by truckAggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsCanadian aggregates:- strong- desirable thermal properties- inexpensive price- uniformity - free from deleterious substances- natural aggregates, not recycled!AggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsSTRONG:• Contribution in high strength concreteAggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsDESIRABLE THERMAL PROPERTIES:• Relatively low coefficient of thermal expansion• Geometry doesn’t change significantly when exposed to temperature changeAggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsINEXPENSIVE PRICE:• ~$16/ton• This price is very insignificant compare to the total construction cost AggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsUNIFORMITY:• Similar texture, size, shape• Similar bulk density for CA and FA (2.66-2.68)• Help achieve the desired workability• No segregation!AggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsFREE FROM DELETERIOUS SUBSTANCE:• Caltrans has a laboratory in Richmond to test the aggregates sample• The test include: gradation test, sand equivalent test, CV test (cleanliness evaluation)• They test the aggregates dailyAggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsNATURAL AGGREGATES, NOT RECYCLED:• Caltrans doesn’t allow recycled aggregates• Recycled aggregates might not last long• Recycled aggregates might contain reactive substancesAggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsLocal Aggregates Used:• Limestone from San Jose area• Limestone possess very good thermal propertiesAggregateThe San Francisco-Oakland Bay Bridge Seismic Safety ProjectsWhy not use more local aggregates?• Most of the aggregates found are weak• Good aggregates are rare and expensive• Different source of CA and FA -> significant difference in bulk densityAggregateThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Normal tap water• Environmental impact Æ not a concern yet• Solid (shaved ice) & Liquid• Shaved Ice:– Lower temperature– Up to 50%WaterThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Surfactants:– Air-entraining– Water-reducing (superplasticizer)• Mineral admixtures:–Fly Ash–Slag– Metakaolin• Chemical admixtures:– Accelerator– RetarderAdmixtureThe San Francisco-Oakland Bay Bridge Seismic Safety Projects•Others:– Viscosity Modifying Agent– Shrinkage ReducerAdmixtureThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Reasons:– Seismic impact (column)– Maintain good quality• Effects:– Reduce strength (15%-20%)– Lower E• Amount: 5%-6%Air EntrainingThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• ADVA flow (Grace) & Glenium 3400 (Degussa)• Amount: 65 ounces/yard^3• Main reason: Fluidize concrete (high reinforcement) without lowering the strength• Other advantages:– Rapid batching– No significant segregation– Easy finishing• Change slump from 2”-3” to 8”-9”SuperplasticizerThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Type F (< 10% CaO)• Amount: 25%• Advantages:– Low reactivity– Improve workability– Higher ultimate strength– Reduce tendency to segregate & bleedingFly AshThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Amount: 50%• Advantages:– Improve durability & workability– Reduce bleeding• Problem: color changeSlagThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Only for backfilling• Setting time < 4 hours• Amount: 16 ounces/yard^3AcceleratorThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• Recover (Grace)• Use in: pier table, column, pile (cover dam)• Reasons: – reduce heat– increase setting time• Setting time: 6-8 hours• Amount: 22-23 ounces/yard^3RetarderThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• V-MAR 3 (Grace)•Polymer• Increase viscosity while holding concrete together• Self Consolidating Concrete (SCC)• Reduces bleedingViscosity Modifying AgentThe San Francisco-Oakland Bay Bridge Seismic Safety Projects• M.B Tetraguard AS20 (Master Builders)• Use in


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