What is the history of cement? How is it manufactured? What are the types of cements?My nephew wants to be a cement man in the future, and needs those info. He needs my contacts to help him evaluate if he actually likes the cement man idea in particular and the cement industry in general. Thanks for your help.
Just how long have condoms been around? The answer might surprise you. Most people think that condoms have been around and in use for a few hundred years, but they are wrong. On a cave wall in France is a painting of a man using a condom. This painting is between 12,000 and 15,000 years old, so condoms have been around for thousands of years, not hundreds. Condoms have been made out of a variety of materials over the years including linen, animal intestines, oiled paper, latex, and polyurethane. Currently only latex, polyurethane, and animal tissue condoms are available on the US market, but only the latex condoms have been shown to be effective in preventing the spread of STDs.
I found two very good sites. The first one has a brief but informative history as well as details on aspects of the current cement industry. The second one is very detailed on the manufacturing of cement and includes its own history as well.
