50 Fun Facts About Concrete

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

It is also the most widely used building material and the most-manufactured material on Earth.

What are the two basic components of concrete?

Cement-bound concrete differs from asphalt concrete, which uses a bituminous binder.

What is the chemical process by which cement reacts with water and hardens?

The reaction is exothermic, so ambient temperature affects how fast concrete sets.

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

Mortar is mainly used as a bonding agent for bricks and tiles; grout also lacks coarse aggregate.

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

Concretus is 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?

The Assyrian Jerwan Aqueduct of 688 BC also used waterproof concrete.

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

They discovered hydraulic lime by 700 BC and built kilns for mortar in southern Syria and Jordan.

What did the Romans call their concrete?

It was made from quicklime, pozzolana and pumice aggregate.

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

The Colosseum was also built largely of concrete.

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

The pyroclastic material reacts with seawater to form Al-tobermorite crystals over time.

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?

A copy at Charlemagne's scriptorium produced many of the surviving medieval copies.

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

A 16th-century Venetian dockyard had already used hydraulic lime mortar in its foundations.

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?

His son William continued developments into the 1840s.

Why did Aspdin name his cement after Portland?

Portland stone was quarried in Dorset, England.

Who is credited with inventing reinforced concrete in 1849?

He also designed and built the first reinforced concrete bridge in 1875.

Who built the first reinforced concrete house, in 1853?

He introduced iron reinforcement in the 1850s; steel followed with G. A. Wayss in the 1880s.

Which French engineer patented prestressed concrete on 2 October 1928?

Tendon cables compress the concrete to strengthen it against tension.

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

The heated product is called clinker; the gypsum is a source of sulfate.

What is the intermediate product of the cement kiln called before it is ground into cement?

Producing a ton of it takes 3.3 to 3.6 gigajoules of energy even in efficient kilns.

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?

More water gives a freer-flowing mix with a higher slump but less strength.

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?

Air entrainment is nonetheless used because it 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 simple measure of workability is taken by filling and lifting an 'Abrams cone'?

A dry mix slumps only an inch or two; a wet one may slump eight inches.

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

In North America it is blacktop or pavement; the process was refined by Belgian immigrant Edward De Smedt.

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

Rain drains through it to the soil below, recharging aquifers instead of causing runoff.

Bacteria such as Bacillus pasteurii are added to some concretes to do what?

Some strains also cut corrosion of rebar by up to four times.

Concrete is strong in compression but weak in what?

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

What is the usual minimum cover of concrete above and below steel reinforcement to prevent spalling and corrosion?

Reinforcement is placed where tension is expected, such as the lower part of beams.

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

Hydration is exothermic, so huge pours can take months 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 is often used as fire protection for steel itself.

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?

A tonne of concrete is responsible for about 100 to 200 kg of CO2.

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

Calcination drives CO2 out of the limestone itself, so it cannot be fixed just by cleaner fuel.

Which project holds the record for the largest concrete pour, an estimated 16 million cubic metres over 17 years?

Brazil's Itaipu previously held the record with 12.3 million cubic metres.

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

It was set during a hydroelectric project in Himachal Pradesh.

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

13,200 cubic metres were poured in 54 hours despite a tropical storm.

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

OSHA's 2017 rule limits breathable crystalline 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?

Stephens found the walls 'almost as hard as rock'.

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

It is placed as a dry mix in thick layers and compacted by rollers.

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

Divers pierce the bags with rebar pins to tie layers together and let hydration begin.

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?

Its hard surfaces still add to runoff, erosion and flooding.

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

Some additives can also raise toxicity concerns.

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

Joseph Aspdin's son William carried the development on into the 1840s.

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

Its tiny particle size gives a huge surface-to-volume ratio, which speeds the pozzolanic reaction in the mix.