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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 empirically by Feret: = / where S is the strength of concrete
Concrete hardens as a result of the chemical reaction between cement and water (known as hydration and producing heat). For every mass (kilogram, pound, or any unit of weight) of cement (c), about 0.35 mass of water (w) is needed to fully complete the hydration reactions. [1]
United States weight laws under the Federal Bridge Formula (FBF) require a three-axle ready mixed concrete truck to weigh 48,000 pounds (22,000 kg) or under. This leaves only 18,000 pounds (8,200 kg) for concrete to be carried, as 30,000 pounds (14,000 kg) is the tare weight of the truck.
The Oxford English Dictionary has a definition of "bag" as "A measure of quantity for produce, varying according to the nature of the commodity" and has quotations illustrating its use for hops in 1679, almonds in 1728 (where it is defined by weight as "about 3 Hundred Weight" i.e. 336 pounds (152 kg) in Imperial units) and potatoes in 1845 ...
Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]
The effect of mulch upon soil moisture content is complex. Mulch forms a layer between the soil and the atmosphere reducing evaporation. [11] However, mulch can also prevent water from reaching the soil by absorbing or blocking water from light rains and overly thick layers of mulch can reduce oxygen in the soil. [12]
The phase composition of a particular cement can be quantified through a complex set of calculation known as the Bogue formula. To avoid the flash setting of concrete, due to the very fast hydration of the tricalcium aluminate (C 3 A), 2–5 wt. % calcium sulfate is interground with the cement clinker to prepare the cement powder.
Concrete is damaged if it does not reach a strength of 500 pounds per square inch (3.4 MPa) before freezing. [ 3 ] : 19 Typical chemicals used for acceleration today are calcium nitrate (Ca(NO 3 ) 2 ), calcium nitrite (Ca(NO 2 ) 2 ), calcium formate (Ca(HCOO) 2 ) and aluminium compounds.