September 6, 1901. President William McKinley is shot at the Pan American Exposition in Buffalo, NY. Anarchist Leon Czolgosz is arrested in connection with the attack. September 14, 1901. McKinley dies of complications from his bullet wounds. Vice President Theodore Roosevelt assumes the presidency.
Concrete slab. A concrete slab is a common structural element of modern buildings. Horizontal slabs of steel reinforced concrete, typically between 4 and 20 inches (100 and 500 millimeters) thick, are most often used to construct floors and ceilings, while thinner slabs are also used for exterior paving.
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement that hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, such as calcium aluminate cements. However, asphalt concrete, which is frequently used for road surfaces, is also a type of concrete, where the cement material is bitumen, and polymer concretes are sometimes used where the cementing material i