Vật liệu nhẹ cho xây cầu nhanh

Vật liệu nhẹ cho xây cầu nhanh

Reid W. Castrodale, PhD, PECarolina Stalite CompanyStructural Lightweight Concretefor Accelerated Bridge ConstructionROTARY KILN PRODUCEDSTRUCTURAL LIGHTWEIGHT AGGREGATEEXPANDED SHALE,CLAY AND SLATEINSTITUTEAASHTO T-4 MeetingJune 28, 2005 2Structural Lightweight AggregateManufactured aggregate• Expanded shale, clay or slate• Manufactured in a rotary kiln 3Structural Lightweight AggregateQuality control• Manufacturing• Storage• Shipping 4ESCS Manufacturing Plants in US20 plants in the USSee www.escsi.org for locations 5Specific Gravity ofLightweight vs. Normal Weight AggregateSpecific gravity for rotary kiln expandedlightweight aggregates• Range from 1.3 to 1.6Specific gravity for normalweight aggregates• Range from 2.6 to 3.0SoilGravelESCSAgg.LimestoneSand1 lb. of each type of aggregate 6Unit Weight ofLightweight vs. Normal Weight ConcreteLightweight concrete• 103 to 125 lbs per cubic footNormal weight concrete• 140 to 150 lbs per cubic footSpecified density concrete• Between the above ranges• Combination of lightweight and normalweight aggregates 7Benefits of Using Lightweight ConcreteMain benefits• Reduced dead load of structure• Improved durability• Reduced handling and transportationcosts for precast components- Discussed later in presentation withapplications and projects 8Benefits of Using Lightweight ConcreteReduced dead load• A typical reduction of 25-35% in dead loadcompared to normal weight concrete• Improves efficiency of designs- Increased spans- Wider girder spacings- Increased deck width on same superstructure- Reduced foundations- Reduced reinforcement and prestressing- Reduced structure mass for seismic designs- Reduced transportation costs for precast 9Compressive strength• Structural lightweight concrete isspecified as having a minimumcompressive strength of 2,500 psi• Depending on the type of aggregatesspecified, structural lightweight concretescan achieve compressive strengths up to12,000 psiBenefits of Using Lightweight Concrete 10Improved bond between cement paste andlightweight aggregates• Cellular structure and irregular surface ofaggregate (mechanical bond)• Chemistry of the aggregates and cement(pozzolanic bond)• Transition zone• Improves durabilityby reducing crackingBenefits of Using Lightweight Concrete 123doc.vn