MIDTERM CONST. MAT. - LESSON 6

WHAT IS CEMENT?

the chemical binder

the difference between it and concrete is that concrete is the finished product

CEMENT DERIVED FROM THE LATIN

“CAE-MENTUM” (STONE CHIPPINGS).

code: CEA (swap EA) MENT UM(E)

THE ANCIENT PIONEERS (12,000 BCE – 1400S)

EGYPTIANS USED:

GYPSUM/LIME MORTARS

(EXCELLENT FOR DRY WEATHER, BUT DISSOLVED IN RAIN).

EARLY BINDERS WERE "NON-HYDRAULIC"

THESE EARLY CEMENTS REQUIRED AIR

GYPSUM

IS EASIER TO PROCESS THAN LIME BECAUSE IT REQUIRES LESS HEAT, BUT IT IS WATER-SOLUBLE. THIS IS WHY THE PYRAMIDS SURVIVED IN THE DESERT, BUT WOULDN'T HAVE LASTED IN A RAINFOREST

THE ROMAN SUPER-WEAPON (300 BCE)

POZZUOLANA (VOLCANIC ASH).

VOLCANIC ASH FOUND NEAR MOUNT VESUVIUS. WHEN ROMANS MIXED THIS ASH WITH LIME, THEY CREATED A HYDRAULIC CEMENT.

POZZUOLANA (VOLCANIC ASH)

instead of air it could set underwater

aka the 1st hydraulic cement

PANTHEON

the 2,000 year old, largest reinforced concrete dome

modern concrete last only 50-100 years

a specific mineral called aluminous tobermorrite that grows stronger over time when exposed to moisture

"FAT LIME" MORTARS

medieval catherabls were bulit

flexible but weak if the building is too tall or the moratar stay wet

THE INDUSTRIAL AWAKENING (1750 – 1800)

SMEATON TESTED VARIOUS LIMESTONES AND FOUND THAT "BLUE LIAS" (WHICH CONTAINED A HIGH AMOUNT OF CLAY) PRODUCED A CEMENT THAT HARDENED EVEN WHILE BEING POUNDED BY THE ATLANTIC OCEAN. THIS PROVED THAT "IMPURITIES" LIKE SILICA AND ALUMINA WERE ACTUALLY THE SECRET TO STRENGTH. THIS LED TO

THE DISCOVERY OF LIMESTONE CONTAINING CLAY (ARGILLACEOUS LIMESTONE), WHICH TURNED INTO A ROCK-HARD BINDER THAT RESISTED SALT WATER.

"BLUE LIAS"

PRODUCED A CEMENT THAT HARDENED EVEN WHILE BEING POUNDED BY THE ATLANTIC OCEAN

ARGILLACEOUS LIMESTONE

WHICH TURNED INTO A ROCK-HARD BINDER THAT RESISTED SALT WATER.

FATHER OF CIVIL ENGINEERING

JOHN SMEATON (1724–1792) WAS A PIONEERING BRITISH CIVIL ENGINEER FOR FORMALIZING THE PROFESSION AND INTRODUCING SCIENTIFIC METHODOLOGY TO CONSTRUCTION. RENOWNED FOR DESIGNING THE THIRD EDDYSTONE LIGHTHOUSE USING INNOVATIVE HYDRAULIC LIME, HE ALSO DESIGNED NUMEROUS BRIDGES, CANALS, AND HARBOURS.

THE "PORTLAND" REVOLUTION

JOSEPH ASPDIN, A BRICKLAYER WHO COOKED HIS MIXTURES IN HIS KITCHEN STOVE. HE TOOK FINELY GROUND LIMESTONE AND CLAY, BURNED THEM UNTIL THE CARBON DIOXIDE WAS DRIVEN OFF, AND THEN GROUND THE RESULT INTO A FINE POWDER.

HE CALLED IT "PORTLAND CEMENT" TO TRICK PEOPLE INTO THINKING IT WAS AS HIGH- QUALITY AS THE FAMOUS PORTLAND STONE USED IN LONDON’S FINEST BUILDINGS.

JOSEPH ASPDIN

THE FIRST TRUE ARTIFICIAL CEMENT, WHICH HE CALLED PORTLAND CEMENT, IN 1824; THE NAME IMPLIED THAT IT WAS OF THE SAME HIGH QUALITY AS PORTLAND STONE. TO MAKE PORTLAND CEMENT, ASPDIN BURNED LIMESTONE AND CLAY TOGETHER IN A KILN; THE CLAY PROVIDED SILICON COMPOUNDS, WHICH WHEN COMBINED WITH WATER FORMED STRONGER BONDS THAN THE CALCIUM COMPOUNDS OF LIMESTONE.

KILN

A FURNACE OR OVEN FOR BURNING, BAKING, OR DRYING, ESPECIALLY ONE FOR CALCINING LIME OR FIRING POTTERY.

THE MODERN TITAN (ROTARY KILNS & STEEL)

IN THE LATE 1800S, THE ROTARY KILN WAS INVENTED. INSTEAD OF COOKING CEMENT IN SMALL BATCHES, WE COULD NOW PRODUCE IT IN MASSIVE, CONTINUOUS ROTATING TUBES AT 140 DEGREES CELSIUS.

JOSEPH MONIER

REALIZED THAT ADDING STEEL MESH TO CONCRETE ALLOWED IT TO HANDLE "TENSION" (PULLING FORCES), NOT JUST "COMPRESSION" (PUSHING FORCES).

THE ENVIRONMENTAL & HIGH-TECH FUTURE

60% OF CEMENT’S CO DOESN’T COME FROM THE FUEL USED TO HEAT THE KILNS—IT COMES FROM THE CALCINATION PROCESS ITSELF. WHEN YOU HEAT LIMESTONE , IT CHEMICALLY SPLITS INTO LIME AND RELEASES AS A BYPRODUCT.

SELF-HEALING MECHANISMS

CONCRETE IS PRONE TO "MICRO-CRACKING" DUE TO THERMAL EXPANSION OR HEAVY LOADS. WHEN WATER ENTERS THESE CRACKS, IT CAN RUST THE STEEL REBAR INSIDE, CAUSING STRUCTURAL FAILURE.

BACILLUS BACTERIA

(A TYPE THAT CAN SURVIVE IN HIGHLY ALKALINE ENVIRONMENTS) INTO THE CONCRETE IN TINY CAPSULES.

WHEN A CRACK FORMS, THE CAPSULE BREAKS. WATER ENTERS,"WAKING UP" THE BACTERIA. THEY CONSUME ADDED NUTRIENTS (LIKE CALCIUM LACTATE) AND EXCRETE CALCIUM CARBONATE (LIMESTONE), WHICH GROWS INTO THE CRACK AND SEALS IT SHUT.

3D CONCRETE PRINTING (3DCP)

TRADITIONAL CONSTRUCTION IS INCREDIBLY WASTEFUL; YOU HAVE TO BUILD WOODEN FORMS (MOLDS) FOR EVERY WALL, THEN THROW THE WOOD AWAY. 3DCP "EXTRUDES" A SPECIFIC, FAST-SETTING CONCRETE MIX LAYER-BY-LAYER.

CEMENT PRODUCTION PROCESS

1. LIMESTONE QUARRYING

2. CRUSHING AND TRANSPORT

3. PREHEATER TOWER

4. CLINKER COOLING (RAW MATERIALS)

5. GRINDING (CLINKER)

6. PACKAGING AND SHIPPING (FINAL PRODUCT)

NOTE THE YT VIDEO