I.2. Electrical Energy Storage and Portable Power Sources Single-use batteries Electrical energy storage was developed by Alessandro Volta in the late 1700s, and chemistry has contributed to subsequent improvements in battery power. The 1890 carbon-zinc dry cell improved upon the earlier Leclanché ’wet-cell’ design. It was commercially produced for use in flashlights and it is still in use today. In 1949, a new alkaline paste for the traditional battery enhanced lifetime and allowed miniaturization. This alkaline battery quickly found many uses in portable electronic devices and cameras. Since then, newer battery models have used silver oxide, mercuric oxide, or lithium. Carbon-zinc dry battery

I.2. Electrical Energy Storage and Portable Power Sources Rechargeable batteries The 1859 lead-acid rechargeable battery was an early commercial example of using a controlled chemical reaction to produce electricity. Improved upon in 1881 and continuously enhanced since, the lead-acid battery continues to be the dominant form of battery used in automobiles and trucks. The nickel-cadmium rechargeable battery, first built in 1899, was too expensive to compete commercially. Modern developments have focused on lithium. After a failed attempt to use lithium metal in the 1980s, lithium-ion batteries are now commonplace, finding applications in cellular phones and laptop computers.

I.3. Materials for Roadways and Bridges Concrete The massive U.S. interstate construction projects of the 1950s depended heavily on the strength and longevity of concrete for roads and bridges. Portland cement, first made in 1824 and patented as reinforced concrete by the Frenchman Joseph Monier in 1877, slow- sets due to a complex chemical reaction in which the cement paste fills the void between particulates and any reinforcements. Its durability and strength depend on careful control of the cement manufacturing process. Adding different chemicals to the initial concrete mixture can reduce shrinkage and improve corrosion resistance.

I.3. Materials for Roadways and Bridges Asphalt Asphalt is a popular road construction material today because of its cost and performance advantages. Natural asphalt was discovered in 1595, but it was not bound with coal tar and used to pave roadways until Bitumen, the solid or semi-solid residue of the refinery process to make gasoline from petroleum, quickly replaced natural asphalt for paving roads. Recently, synthetic polymers have been added to improve performance and durability. Superpave (an acronym for Superior Performing Asphalt Pavements) is the latest technique for making superior asphalt that can withstand heavy loads and adverse weather conditions.

I.3. Materials for Roadways and Bridges Metals and alloys Steel has become the primary structural material for bridges due to its light weight, strength, durability, ease of maintenance and construction, low erection costs, and resistance to natural disasters such as earthquakes. New high-performance steels introduced in the 1990s have superior strength and corrosion resistance. Another technology for protecting steel in bridge construction is a process known as metalizing in which aluminum or zinc is sprayed onto a cleaned steel surface to form a 30-year protective coating.

I.3. Materials for Roadways and Bridges Maintenance and repair technique Road infrastructure must be maintained without significant deterioration in all types of weather and on a long timescale. Innovations in construction and maintenance materials have allowed longer intervals between the rebuilding of roads. Sealants for concrete, asphalt, and steel are important to prolonging road life. Other chemical and polymeric material function as binder addictives to enhance the performance of asphalt roadways. For example, styrene- butadiene-styrene results in less rutting and cracking.