问题描述：
英语翻译
Concrete is a mixture that contains cement,sand,gravel,water,and usu-
ally additives.The cement is the material that causes the other ingredients to ad-
here to one another.The water is needed to cause the cement to hydrate.Con-
crete does not harden by drying,but by hydration.The aggregate used to make
concrete should be uniformly graded to provide a good t"111 of all the spaces be-
tween the individual pieces of aggregate.The sand will fill the small spaces in
the mix.Gap-graded aggregates have certain particle sizes entirely or mostly
absent.The lack of two or more successive sizes can create segregation prob-
lems with the concrete mix.The amount of water used in the mix should not be
excessive,because excess water eventually evaporates,leaving small voids in
the spaces it once occupied.The amount of water is controlled by specifying the
water/cement ratio,the amount of water in relation to the amount of cement.
The water/cement ratio is defined as the ratio by weight of the free water content to the cement content.It has been long accepted that a low free water/ce-
ment ratio in a concrete mix is essential for the concrete's subsequent strength
and durability.There are many different additives and they are used for a varie-
ty of purposes from changing the color of the concrete to shortening or lengthe-
ning the time for the concrete to harden.
Concrete is characterized by strong compressive strength,but is relatively
weak in tension and shear.It can support large axial loads,and is used exten-
sively in the foundations of large structures such as bridges and tall buildings.
but it breaks easily under bending without reinforcing steel.Concrete with com-
pressive strength of 3,000 6,000 pounds per square inch (psi) is common.
The American Concrete Institute defines any concrete over 6,000 psi as high-
strength concrete.
Concrete is a mixture that contains cement,sand,gravel,water,and usu-
ally additives.The cement is the material that causes the other ingredients to ad-
here to one another.The water is needed to cause the cement to hydrate.Con-
crete does not harden by drying,but by hydration.The aggregate used to make
concrete should be uniformly graded to provide a good t"111 of all the spaces be-
tween the individual pieces of aggregate.The sand will fill the small spaces in
the mix.Gap-graded aggregates have certain particle sizes entirely or mostly
absent.The lack of two or more successive sizes can create segregation prob-
lems with the concrete mix.The amount of water used in the mix should not be
excessive,because excess water eventually evaporates,leaving small voids in
the spaces it once occupied.The amount of water is controlled by specifying the
water/cement ratio,the amount of water in relation to the amount of cement.
The water/cement ratio is defined as the ratio by weight of the free water content to the cement content.It has been long accepted that a low free water/ce-
ment ratio in a concrete mix is essential for the concrete's subsequent strength
and durability.There are many different additives and they are used for a varie-
ty of purposes from changing the color of the concrete to shortening or lengthe-
ning the time for the concrete to harden.
Concrete is characterized by strong compressive strength,but is relatively
weak in tension and shear.It can support large axial loads,and is used exten-
sively in the foundations of large structures such as bridges and tall buildings.
but it breaks easily under bending without reinforcing steel.Concrete with com-
pressive strength of 3,000 6,000 pounds per square inch (psi) is common.
The American Concrete Institute defines any concrete over 6,000 psi as high-
strength concrete.
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