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Abrams' law (also called Abrams' water-cement ratio law) [1] is a concept in civil engineering. The law states the strength of a concrete mix is inversely related to the mass ratio of water to cement. [1] [2] As the water content increases, the strength of concrete decreases. Abrams’ law is a special case of a general rule formulated ...
Abrams investigated the influence of the composition of concrete mixes on the strength of the end product. Some of the results of his research were: the definition of the concept of fineness modulus; the definition of the water–cement ratio; a concrete slump test for the
A DoS value of 100% meaning that demand and capacity are equal and no further traffic is able to progress through the junction. The formula to calculate DoS is: Degree of saturation = (demand x cycle time) / (saturation flow x effective green time) Values over 85%-90% typically indicate traffic congestion, with queues of vehicles beginning to form.
Headway is the distance or duration between vehicles in a transit system. The minimum headway is the shortest such distance or time achievable by a system without a reduction in the speed of vehicles. The precise definition varies depending on the application, but it is most commonly measured as the distance from the tip (front end) of one ...
Three parallel escalators; the direction of the middle escalator can be changed to double capacity in one direction (↑↑↓ or ↑↓↓).. Many public transport systems handle a high directional flow of passengers— often traveling to work in a city in the morning rush hour and away from the said city in the late afternoon.
Bay Area Rapid Transit: 1,676 mm (5 ft 6 in) 100 m (328 ft) Batlow, New South Wales: 1,435 mm (4 ft 8 + 1 ⁄ 2 in) Rolling stock limited to 500 long tons (510 t; 560 short tons) and 300 m (984 ft) - restricted to NSW Z19 class 0-6-0 steam locomotives 95 m (312 ft) Newmarket, New Zealand: 1,067 mm (3 ft 6 in) Extra heavy concrete sleepers [10]
The ultimate strength of concrete is influenced by the water-cementitious ratio (w/cm), the design constituents, and the mixing, placement and curing methods employed.All things being equal, concrete with a lower water-cement (cementitious) ratio makes a stronger concrete than that with a higher ratio. [2]
A w/c ratio higher than 0.60 is not acceptable as fresh concrete becomes "soup" [2] and leads to a higher porosity and to very poor quality hardened concrete as publicly stated by Prof. Gustave Magnel (1889-1955, Ghent University, Belgium) during an official address to American building contractors at the occasion of one of his visits in the ...