47 Fun Facts About Concrete

Concrete is the second-most-used substance in the world after what?

Only water is consumed in greater quantity than concrete, which is the most widely used building material on Earth and, by mass, the most-manufactured material of any kind.

What are the two basic components of concrete?

Concrete is aggregate bound by a cement: sand and gravel held together by a paste of cement and water, usually Portland cement, that hardens around them.

What is the chemical process by which cement sets and hardens into a solid?

Hydration is the reaction between cement and water that forms calcium silicate hydrate; it is exothermic, so ambient temperature affects how fast concrete sets.

How does mortar, used to bond bricks, differ from concrete?

Mortar contains only fine aggregates, sand bound by cement or lime with no gravel, which keeps it workable enough to spread between bricks, blocks and tiles.

The word 'concrete' comes from a Latin word meaning what?

Concrete comes from Latin concretus, 'compact or condensed', the perfect passive participle of concrescere, 'to grow together'.

Concrete floors dating to roughly 1400-1200 BC were found in the royal palace of which Greek site?

Concrete floors were found in the royal palace at Tiryns, the Mycenaean citadel in the Argolid; the Assyrian Jerwan Aqueduct of 688 BC later used waterproof concrete.

Which desert traders pioneered concrete-like materials and kept their waterproof cisterns secret?

The Nabataeans, whose capital was Petra, used hydraulic lime by about 700 BC and built mortar kilns in southern Syria and northern Jordan; hidden cisterns let them thrive in the desert.

What did the Romans call their concrete?

Opus caementicium was the Roman name for concrete, from caementa, the rubble aggregate bound in lime mortar; the word survives in 'cement'.

Which Roman building has the world's largest unreinforced concrete dome?

The Pantheon's dome, completed under Hadrian around 126 AD, spans 43.3 metres; its concrete grows lighter toward the oculus, with pumice aggregate in the upper rings.

What volcanic ingredient gives Roman concrete its remarkable durability and resistance to seawater?

Pozzolana ash, volcanic ash from around Pozzuoli near Naples, reacts with lime and seawater to form aluminous tobermorite crystals that strengthen the concrete over centuries.

What technique has been proposed as the source of Roman concrete's 'self-healing' ability?

The lime clasts can dissolve and recrystallise to fill cracks.

Which Roman treatise, rediscovered by Poggio Bracciolini in 1414, contained a description of Roman cement?

Vitruvius's De architectura, the only complete architectural treatise to survive from antiquity, describes Roman lime mortars and cements; its rediscovery by Poggio Bracciolini in 1414 inspired Renaissance architects such as Alberti.

Which French waterway linking the Atlantic and the Mediterranean was built using concrete in 1670?

The Canal du Midi, built by Pierre-Paul Riquet between 1666 and 1681 from Toulouse to the Mediterranean, used concrete in its works; the Canal Saint-Martin is a 19th-century Paris canal.

John Smeaton pioneered hydraulic lime in concrete while building a light on which rocks off Devon in the 1750s?

Smeaton's Tower was the third Eddystone Lighthouse.

Who patented Portland cement in 1824?

Joseph Aspdin, a Leeds bricklayer, patented Portland cement on 21 October 1824; his son William later produced the harder-fired version closer to the modern material.

Why did Aspdin name his cement after Portland?

Portland stone was quarried in Dorset, England.

Who is credited with inventing reinforced concrete in 1849?

Joseph Monier, a Parisian gardener, made iron-reinforced concrete flowerpots in 1849 and patented the idea in 1867; he built the first reinforced concrete bridge at Chazelet in 1875.

Who built the first reinforced concrete house, in 1853?

François Coignet built the first iron-reinforced concrete house in 1853 in Saint-Denis, near Paris; steel reinforcement followed with G. A. Wayss in the 1880s.

Which French engineer patented prestressed concrete on 2 October 1928?

Eugène Freyssinet patented prestressed concrete in 1928; tensioned steel tendons keep the concrete in compression so it resists cracking under bending loads.

Portland cement is made by heating limestone with clay or shale and grinding the resulting product with what?

Gypsum is ground in with the kiln product to supply sulfate that slows the early setting reaction, giving crews time to place and finish the concrete.

What difficult-to-dispose-of waste is the most common alternative fuel for cement kilns?

The kilns' extreme temperatures burn even awkward fuels completely.

According to Abrams' law, what does a lower water-to-cement ratio produce?

Abrams' law, stated by Duff Abrams in 1918, says a lower water-to-cement ratio gives stronger, more durable concrete; surplus water leaves pores behind as it evaporates.

Fly ash, a common mineral admixture, is a by-product of what?

Ground blast-furnace slag comes from steelmaking and silica fume from electric arc furnaces.

Each 1% of entrained air in concrete may reduce its compressive strength by roughly how much?

Roughly 5% of compressive strength is lost for each 1% of entrained air, yet the microscopic bubbles give freezing water room to expand, so air entrainment greatly reduces freeze-thaw damage.

Why is calcium chloride, an effective accelerator, prohibited in some countries?

Nitrates are used instead even though they work less well.

What is asphalt concrete commonly called in the UK and Ireland?

In the UK and Ireland asphalt concrete is loosely called tarmac, after Edgar Hooley's 1902 tar-macadam patent; North Americans say blacktop or pavement.

Pervious or 'no-fines' concrete contains what percentage of interconnected air voids?

Pervious concrete has 15 to 25 percent interconnected voids because it is made with little or no sand; rain drains through it into the soil, recharging aquifers instead of running off.

Concrete resists crushing loads well but is weak under which kind of stress?

That is why steel rebar, strong in tension, is embedded in it.

Which Swiss engineer designed the Salginatobel Bridge, a 1930 reinforced concrete arch?

Robert Maillart designed the Salginatobel Bridge near Schiers, a 90-metre three-hinged reinforced concrete arch completed in 1930 and later named an International Historic Civil Engineering Landmark.

Which dam used a network of cooling pipes between concrete placements to stop its mass concrete overheating?

Hoover Dam's builders embedded nearly 600 miles of one-inch pipe carrying refrigerated water through the blocks; a single mass pour would otherwise have taken more than a century to cool.

What is a 'tremie'?

It stops turbulent water washing cement out of the mix.

Concrete buildings resist fire better than steel frames because concrete has what property?

Concrete's lower heat conductivity means a structure heats slowly in a fire, while bare steel loses strength rapidly above about 500 C; concrete is often cast around steel as fireproofing.

On average, producing 1,000 kg of cement releases roughly how much CO2?

The cement industry is one of the three main CO2 producers alongside energy and transport.

Roughly how many tonnes of concrete are used worldwide each year?

More than 10 billion tonnes of concrete are used each year, roughly 30 billion tonnes in recent estimates; each tonne accounts for about 100 to 200 kg of CO2.

Roughly what share of cement's greenhouse emissions comes from calcination rather than fuel combustion?

About 60% of cement's CO2 comes from calcination, the kiln reaction that drives CO2 out of limestone to make lime; the rest comes from burning fuel, so cleaner fuel alone cannot fix it.

Which project set the record for concrete poured, 16 million cubic metres over 17 years?

The Three Gorges Dam on the Yangtze took an estimated 16 million cubic metres of concrete over 17 years of construction from 1994, overtaking Brazil's Itaipu Dam at 12.3 million.

The 2009 world record for concrete pumping, at India's Parbati project, reached what vertical height?

Concrete was pumped 715 metres vertically in 2009 at the Parbati Hydroelectric Project in Himachal Pradesh, India, surpassing the 606 metres reached at the Burj Khalifa in 2008.

The 1992 record for a continuous concrete raft pour, later beaten in Abu Dhabi, was set building which Kuala Lumpur landmark?

The Petronas Towers' foundation raft took 13,200 cubic metres of concrete in a 54-hour continuous pour in 1992, despite a tropical storm; Abu Dhabi's Landmark Tower beat it in 2007.

Grinding concrete or handling cement dust exposes workers to which lung disease?

Silicosis, scarring of the lungs from inhaled crystalline silica, is the risk; OSHA's 2017 rule limits respirable silica to 50 micrograms per cubic metre over an 8-hour day.

The Mayan ruins at Uxmal, described by John L. Stephens, show early use of concrete for what?

At Uxmal, Stephens recorded flat roofs 'covered with cement' and cement floors, with walls of stone set in mortar 'almost as hard as rock', in his 1843 Incidents of Travel in Yucatan.

Roller-compacted concrete is used for mass structures like dams mainly because it does what?

Roller-compacted concrete uses far less cement and water than conventional mixes, so it generates much less hydration heat and needs much less cooling; it is spread in thick lifts and compacted by vibratory rollers.

Bagwork concrete placed underwater by divers generally reaches full strength within how many days?

Like most concrete, bagwork reaches its design strength at about 28 days; divers stack the bags in a bonded pattern and often pin them with steel bars so the layers knit as the cement hydrates.

ICFs, stackable hollow blocks that are filled with reinforced concrete to form walls, are made of what?

They are stacked to form walls before the pour.

Compared with asphalt, concrete contributes to the urban heat island effect how?

Concrete contributes less to the urban heat island effect than asphalt because its paler surface reflects more sunlight, a higher albedo, though its hard surface also adds to runoff and flooding.

Fresh, uncured concrete must be handled with protective equipment because it is what?

Fresh concrete is highly alkaline, with a pH of around 12 to 13 from the calcium hydroxide in the cement paste, so skin contact can cause chemical burns; gloves and boots are essential.

In which English county is the Isle of Portland, source of the stone that named Portland cement?

The Isle of Portland is a limestone peninsula on the Dorset coast south of Weymouth; its pale Portland stone, quarried there for centuries, gave Portland cement its name.

Silica fume, an admixture with particles 100 times smaller than fly ash, is a by-product of making what?

Silica fume is collected from the flue gases of electric arc furnaces making silicon and ferrosilicon alloys; its tiny particles give a huge surface area, which speeds the pozzolanic reaction.