WHAT IS CONCRETE/WHAT MAKES IT STRONG?
Are Concrete & Cement the Same Thing?
CONCRETE IS A building material made by grinding calcined limestone and clay to a fine powder, which can be mixed with water to make concrete (An ingredient) CEMENT IS a construction material made of a mixture of cement, sand, stone, and water that hardens to a stonelike mass
WHAT IS THE MAIN REASON THEY USE CONCRETE IN CONSTRUCTION?
STRENGTH
WHAT ARE TYPES OF CONSTRUCTION MATERIAL STRENGTHS?
COMPRESSIVE STRENGTH TENSILE STRENGTH TORSION
WHICH STRENGTH DOES CONCRETE HAVE MORE OF?
Compressive Strength
What can give concrete more tensile strength?
STEEL REBAR STEEL MATS OR
FIBER Steel/Glass/Synthetic/Natural
THERE IS A CHEMICAL REACTION THAT GIVES CONCRETE IT’S STRENGTH? WHAT IS THIS REACTION CALLED?
Who says it is evaporation? Who says it hydration?
-Hydration occurs when water chemically combines with a substance. -When water is added to the concrete mixture of cement and aggregates, the chemical reaction hydration begins. IT’S Hydration Calcium Silicate & Water
- Concrete gets hot temperature wise and chemically. -If it stays on your skin to long you will get a chemical burn
HAVE YOU EVER SEEN ANYBODY WATER CONCRETE AFTER ITS BEEN FINISHED, LIKE THEY WATER GRASS? The longer concrete stays hydrated the stronger it will get… It can still be hardening after 100 years ….
What can affect the strength of concrete?
TEMPERATURE (HOT & COLD) -FREEZING -CONCRETE WILL LOSE 50% STRENGTH & WILL SPAWL -HEAT -WILL SET UP TO FAST -MAY USE MORE WATER -CAN CAUSE HONEYCOMBING
SPAWLING CAUSED BY COLD WEATHER/TOO MUCH WATER/TROWELING TOO FAST
Honeycombing Causes of honeycomb and voids include stiff or unworkable concrete, segregation, congested rebar, insufficient consolidation, and improper placing practices.
WHAT ELSE WILL EFFECT THE STRENGTH OF CONCRETE?
WATER!! CONCRETE TO WATER (1:4 RATIO)
Water Control -Admixtures -Plasticizers -Reduce Water -Workability -Air Entrainment -Workability -For Extreme Freeze/Thaw Cycles
How will you know if you are using too much water?
TESTS!!
Summary: -Concrete is made up of cement, rock, sand & water -Cement is the ingredient in concrete that gives it bonding power -Strength is the main reason that concrete is used in construction -Tensile strength measures the force required to pull something apart such as rope, wire or a structural beam to the point where it breaks -Concrete has more compressive strength and less tensile and torsion strength -Steel and fiber can give concrete more tensile strength -Hydration is the chemical reaction that produces heat and strength in concrete -Water causes the chemical reaction in concrete to start -Keeping concrete hydrated will make it stronger -Water and temperature can affect the strength of concrete -Spawling or honeycombing reduces the strength of concrete -Chemicals be added to concrete to make it more workable -Too much water can weaken concrete -Water to concrete ratio is 4 to 1
THE END! Thank you!!