Foreign Policy Magazine looks at modern technology in Africa. They have an interesting take.
"Conditions in Africa Are Medieval."Now who in America thinks of cement as modern technology? Cement was known in Roman times. And yet it is modern technology.
Not in the slightest. It's true that some countries in the region are as poor as England under William the Conqueror, but that doesn't mean Africa's on the verge of doomsday. How many serfs had a cellphone? More than 63 million Nigerians do. Millions travel on buses and trucks across the continent each year, even if the average African road is still fairly bumpy. The list of modern technologies now ubiquitous in the region also includes cement, corrugated iron, steel wire, piping, plastic sheeting and containers, synthetic and cheap cotton clothing, rubber-soled shoes, bicycles, butane, paraffin candles, pens, paper, books, radios, televisions, vaccines, antibiotics, and bed nets.
The spread of these technologies has helped expand economies, improve quality of life, and extend health. About 10 percent of infants die in their first year of life in Africa -- still shockingly high, but considerably lower than the European average less than 100 years ago, let alone 800 years past. And about two thirds of Africans are literate -- a level achieved in Spain only in the 1920s.
Modern hydraulic cements began to be developed from the start of the Industrial Revolution (around 1800), driven by three main needs:An now when we need a building or a road we can set up forms and just pour it. At one time I was very interested in cement construction and studied it extensively. How to calculate the forces a finished structure could handle. Where to put the rebar. Pretensioning and a whole lot of other stuff. My friends laughed at me when I told them i was studying cement. Why would a guy who could do advanced electronics be studying an "old" technology like cement? And yet, without cement the world as we know it would not exist. Currently in my area, high quality cement is available for under $100 a cubic yard delivered if you buy a moderate amount (a few truck loads).
* Hydraulic renders for finishing brick buildings in wet climates
* Hydraulic mortars for masonry construction of harbor works etc, in contact with sea water.
* Development of strong concretes.
In Britain particularly, good quality building stone became ever more expensive during a period of rapid growth, and it became a common practice to construct prestige buildings from the new industrial bricks, and to finish them with a stucco to imitate stone. Hydraulic limes were favored for this, but the need for a fast set time encouraged the development of new cements. Most famous among these was Parker's "Roman cement." This was developed by James Parker in the 1780s, and finally patented in 1796. It was, in fact, nothing like any material used by the Romans, but was a "Natural cement" made by burning septaria - nodules that are found in certain clay deposits, and that contain both clay minerals and calcium carbonate. The burnt nodules were ground to a fine powder. This product, made into a mortar with sand, set in 5-15 minutes. The success of "Roman Cement" led other manufacturers to develop rival products by burning artificial mixtures of clay and chalk.
Speaking of high tech, there is something the inventors of cement never thought of but is very handy these days: it makes good shielding material for land based nuclear reactors. And the price is right.