ABCs of Concrete Presented by Chuck Curry www.concrete-pipe.org

ABCs of Concrete What is concrete? Where does it come from? How is it used? Is it all the same?. www.concrete-pipe.org

Early History Ancient Egyptians Mix mud & straw to make bricks 3 Early History Ancient Egyptians Mix mud & straw to make bricks Discover lime & gypsum make better binders… www.concrete-pipe.org

Early History Great Pyramids 3,000 BC 4 Early History Great Pyramids 3,000 BC Held title of tallest man-made structure for 3,800 years! www.concrete-pipe.org

Early History Ancient Chinese Mix water, rice and lime 5 Early History Ancient Chinese Mix water, rice and lime Use mortar to bind bricks… www.concrete-pipe.org

Early History Great Wall of China 3,000 BC 13,000 miles 6 www.concrete-pipe.org

Improving Practices Roman Empire Pozzolans discovered 7 Improving Practices Roman Empire Pozzolans discovered Extensive use of hydraulic lime www.concrete-pipe.org

Improving Methods The Pantheon Largest Unreinforced Concrete Dome. 8 www.concrete-pipe.org

Setbacks Knowledge lost with fall of Rome 400 AD 9 Setbacks Knowledge lost with fall of Rome 400 AD Not “discovered” again for 1200 years! www.concrete-pipe.org

The Renaissance Renaissance Period Scientific method Manufacturing Engineering Importance of recipes www.concrete-pipe.org

Importance of Recipes Mix Designs Consistency Repeatability Increased Confidence in Performance www.concrete-pipe.org

Industrial Methods “But if the Sand be not very sharp, then you may put a greater quantity of Sand, for Morter which hath its due proportion of Sand, is stronger than that which hath less Sand in it, altho' some think otherwise.” - Joseph Moxon, 1678 www.concrete-pipe.org

Industrial Era Refinement of cement Consciousness of aggregates Scientific method Engineering Efficiency www.concrete-pipe.org

Industrial Methods Specialization Knowledge of intended use Mixes specific to use Cost of mixes www.concrete-pipe.org

Modern Era Principle components Primary applications Range of use What and when? www.concrete-pipe.org

Key Benefits Widely Available Economical Continued strength gain Rock and sand is everywhere! Economical Rock and sand generally cheap! Continued strength gain Self-healing properties Relatively easy to make www.concrete-pipe.org

How to Make Concrete? Rock (Coarse Aggregates) Sand (Fine Aggregates) Water Cement Add Admixtures, when needed Mix sounds simple enough… www.concrete-pipe.org

How To Make a Car: Make a Body Add 4 Wheels Install Engine Paint sounds simple enough… www.concrete-pipe.org

All The Same Right? www.concrete-pipe.org

Concrete is not Concrete! Proportions of materials Ratio of water to cement Types of aggregates Types of admixtures All have an effect! www.concrete-pipe.org

Effects of… More rock versus more sand Cement quantity and w/c ratio Smooth versus angular Types of fly ash Types of admixtures www.concrete-pipe.org

Types of Concrete Wet cast Dry Cast Flowable Self-Compacting www.concrete-pipe.org

Wet Cast Slump Concrete Old Days: Today: Achieved with high w/c ratios Often achieved with lower w/c ratios and Water reducing admixtures www.concrete-pipe.org

Wet Cast www.concrete-pipe.org

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Wet Cast Properties Pros Cons Portable More Dense Lower Permeability Lower Absorption Nicer Finish Longer Curing Time Slower Form Cycle Delayed QC Formwork Manpower www.concrete-pipe.org

Wet Cast – Common Uses Slumps ‘generally’ 1-9” slump Major Infrastructure – Dams, Highways Buildings – Columns, footings, beams Architectural – Panels, facades Cast-in-place - Curbs, inlets, manholes Transport – Roads, sidewalks, sleepers Drainage – Pipe, box culverts, etc. Residential – Drives, patios, etc. www.concrete-pipe.org

Dry Cast Zero Slump Concrete Cast and Strip – Mass Production! Lower w/cm ratio www.concrete-pipe.org

Dry Cast Old Days: Today: Tamping – Too slow. Obsolete. Vibrational Compaction Vibromac Packerhead Centrifugal www.concrete-pipe.org

Dry Cast Vibrational Compaction Packerhead Vibromac Centrifugal Denser, faster, surface issues Packerhead Less dense, fastest, aesthetic, weaker Vibromac Part vibration and packing pressure Centrifugal Most dense*, slower, high maintenance * (of modern methods) www.concrete-pipe.org

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Picture of dry cast slump cone? www.concrete-pipe.org

Dry Cast Properties Pros Cons Shorter Curing Time Rapid Form Cycle Earlier Shipping Automated Mass Production! Less Dense Less Aesthetic More Energy Req’d Duplication of Errors www.concrete-pipe.org

Dry Cast – Common Uses Concrete Block Pavers Storm and Sanitary Drainage Concrete Pipe Concrete Box Culverts Manholes www.concrete-pipe.org

Flowable High Fly Ash Content Not Structural Typically used as backfill Voids in trenches Abandoned pipelines Little to no vibration www.concrete-pipe.org

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Self-Compacting Concrete (SCC) Spread not Slump Cement/Admix suspends aggregate Fills the container www.concrete-pipe.org

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SCC Properties Pros Cons No vibration Complex structures Fewer voids Less energy Less time Less manpower Complex structures Fewer voids High admix (cost) Critical proportions Interaction of admixes www.concrete-pipe.org

SCC – Common Uses Manholes & Inlets Utility Vaults BMPs Rehabilitation www.concrete-pipe.org

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Chemical Admixtures Water Reducers Reduce Water Content by 5-10% Increase Strength Decrease Porosity Increases Workability Improves Finish www.concrete-pipe.org

Chemical Admixtures High Range Water Reducers Reduce Water Content > 10% Significant early and final strengths Increased flow without segregation (rheoplasticity) Helpful where vibration inhibited www.concrete-pipe.org

Chemical Admixtures Air Entrainment Increases air content Evenly distributed Increases Durability, esp. to freeze/thaw cycles Reduces Strength www.concrete-pipe.org

Chemical Admixtures Retarders Increase set time Good for long pours in hot weather Extended transport www.concrete-pipe.org

Chemical Admixtures Accelerators Decrease set time Increase early strength Used in cold weather www.concrete-pipe.org

Chemical Admixtures Corrosion Inhibitors Inhibit attacks on reinforcing steel Marine environments Heavy salt use (northern roads) www.concrete-pipe.org

Chemical Admixtures Ensure Proper Dosage Possible Mix Time Changes Negative Synergies How do different admixes interact? Do you want to find out the hard way? www.concrete-pipe.org

Methods of Mixing Many available. Important to remember goal of mixing: Homogenous mixtures Uniform batches Tolerances – Recipes www.concrete-pipe.org

Paddle mixer If you are going to use a lab mixer for trial batching, you would probably use this type of mixer.

Spiral blade or ribbon mixer

Twin Shaft

Turbine pan mixer

What Concrete Would Be Best? Manhole Riser Low Leakage Limit Exposed to Freeze/Thaw Wet Cast with Entrained Air www.concrete-pipe.org

What Concrete Would Be Best? Bridge Beams High Cementitious Contents Multiple Steel Layers SCC www.concrete-pipe.org

What Concrete Would Be Best? Storm Drain Pipe Mass Production Dry Cast www.concrete-pipe.org

Recap Value of Concrete Types of Concrete Similarities / Differences Range of Use / Applications Importance of Recipes Effects of Admixtures Application drives Selection! www.concrete-pipe.org

QUESTIONS? www.concrete-pipe.org