Title Slide - Portland Cement Association

Title Slide - Portland Cement Association

Design and Control of Concrete Mixtures Aggregates for Concrete Design and Control of Concrete Mixtures CHAPTER 8 Design and Control of Concrete Mixtures

Overview

Aggregate Geology Aggregate Classification Characteristics of Aggregates Potentially Harmful Materials

Alkali-Aggregate Reactivity Aggregate Beneficiations Handling and Storing Aggregates Design and Control of Concrete Mixtures Aggregates of Concrete

Design and Control of Concrete Mixtures Aggregate Geology Rock and Mineral Constituents in Aggregates Design and Control of Concrete Mixtures

Aggregate Classification Natural aggregate Manufactured aggregate Recycled-concrete aggregate

Marine-dredged aggregate Design and Control of Concrete Mixtures Bulk Density Normal weight concrete:

1200 kg/m3 to 1750 kg/m3 (75 lb/ft3 to 110 lb/ft3) Lightweight concrete aggregates: 560 kg/m3 to 1120 kg/m3 (35 lb/ft3 to 70 lb/ft3) Heavyweight aggregates: Typically over 2100 kg/m3 (130 lb/ft3) Design and Control of Concrete Mixtures

Natural Aggregate Gravel and sand Mixture of several minerals Pits, rivers, lakes, seabeds Quality depends on parent

bedrock Design and Control of Concrete Mixtures Manufactured Aggregate Crushed rock or air-cooled slag Fine and coarse aggregate

Rough, angular texture Cubical or elongated shape More uniform in size Less likely to be contaminated Design and Control of Concrete Mixtures

Recycled-Concrete Aggregate Design and Control of Concrete Mixtures Recycled-Concrete Aggregate Design and Control of Concrete Mixtures

Marine-Dredged Aggregate

Tidal estuaries, seashore Two concerns: seashells and salt Avoid uncrushed shells Avoid using high chloride aggregates in reinforced concrete Design and Control of Concrete Mixtures

Aggregate Characteristics Characteristics and Tests of Aggregate Design and Control of Concrete Mixtures Aggregate Characteristics

Characteristics and Tests of Aggregate Design and Control of Concrete Mixtures Grading Design and Control of Concrete Mixtures

Grading Design and Control of Concrete Mixtures Grading Limits

Design and Control of Concrete Mixtures Fine-Aggregate Grading Design and Control of Concrete Mixtures Coarse-Aggregate Grading

Design and Control of Concrete Mixtures Coarse-Aggregate Grading Design and Control of Concrete Mixtures Maximum Size vs. Nominal Maximum Size

Maximum size 100% passing Nominal maximum size typically 85% to 95% passing Design and Control of Concrete Mixtures Nominal Maximum Sizing Dmax = 15 B, S, C, 13T

Design and Control of Concrete Mixtures Combined Aggregate Grading Design and Control of Concrete Mixtures

Combined Aggregate Grading Design and Control of Concrete Mixtures Combined Aggregate Grading Design and Control of Concrete Mixtures

Workability Factor Shilstone 1990 Design and Control of Concrete Mixtures

Tarantula Curve http://www.optimizedgraded.com/ Design and Control of Concrete Mixtures Gap-Graded Aggregates

Certain particle sizes omitted, typically one coarse aggregate size Excess coarse aggregate honeycomb, segregate Excess fine aggregate high water demand, shrinkage Properly proportioned mixtures are readily consolidated with vibration Design and Control of Concrete Mixtures

Fineness Modulus Design and Control of Concrete Mixtures Particle Shape and Surface Texture Design and Control of Concrete Mixtures

Particle Shape and Surface Texture Design and Control of Concrete Mixtures Bulk Density and Voids Bulk density mass of aggregate in unit volume

Includes voids 30% - 45% voids in coarse aggregates 40% - 50% voids in fine aggregates Angularity increases voids Design and Control of Concrete Mixtures

Density and Relative Density Density = Relative density x density of water Typically between 2400 and 2900 kg/m3 (150 and 181 lb/ft3) Relative density typically between 2.4 and 2.9

Design and Control of Concrete Mixtures Absorption and Surface Moisture Design and Control of Concrete Mixtures

Bulking Design and Control of Concrete Mixtures Resistance to Freezing and Thawing Design and Control of Concrete Mixtures

D-Cracking Design and Control of Concrete Mixtures Abrasion and Skid Resistance ASTM C131, Standard Test Method for Resistance to

Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine (AASHTO T 96) ASTM C535, Standard Test Method for Resistance to Degradation of Large-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine. Siliceous content > 25% for good skid resistance

Design and Control of Concrete Mixtures Strength Tensile strength 2 MPa to 15 MPa (300 psi to 2300 psi) Compressive strength 65 MPa to 270 MPa (10,000 psi to 40,000 psi)

Rarely tested Design and Control of Concrete Mixtures Shrinkage Shrinkage Characteristics of Aggregates

Design and Control of Concrete Mixtures Shrinkage Carlson 1938 Design and Control of Concrete Mixtures

Fire Resistance and Thermal Properties Dependent on mineral constituents Lightweight aggregates outperform weight aggregates Calcareous aggregates outperform aggregates

Coefficient of thermal expansion 0.55 x 10-6 /C to 5 x 10-6 /C (1 x 10-6 /F to 9 x 10-6 /F) normalsiliceous Potentially

Harmful Materials Design and Control of Concrete Mixtures Design and Control of Concrete Mixtures

Potentially Harmful Materials Design and Control of Concrete Mixtures Potentially Harmful Materials Design and Control of Concrete Mixtures

Alkali-Silica Reaction Classification of aggregate reactivity ASTM C1778, Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete

Design and Control of Concrete Mixtures Alkali-Carbonate Reaction Rare due to general unsuitability of reactive aggregates Tested through: Petrographic examination (ASTM C295)

Rock cylinder method (ASTM C586) Concrete prism test (ASTM C1105) Design and Control of Concrete Mixtures Aggregate Beneficiation Improving quality through processing

Heavy media separation Jigging Rising-current classification Crushing Design and Control of Concrete Mixtures

Handling and Storing Aggregates Design and Control of Concrete Mixtures Handling and Storing Aggregates Design and Control of Concrete Mixtures

Summary

Geology Classification Characteristics of Aggregates Potentially Harmful Materials

Alkali-Aggregate Reactivity Beneficiation Handling and Storage Design and Control of Concrete Mixtures ?

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