密保Building construction concrete crack of prevention and proce

Building construction concrete crack of prevention and

processing

Abstract

The crack problem of concrete is a widespread existence but again difficult in solve

of

engineering

actual

problem,

this

text

carried

on

a

study

analysis

to

a

little

bit

familiar

crack

problem

in

the

concrete

engineering,

and

aim

at

concrete

the

circumstance put forward some prevention, processing measure.

Keyword:

Concrete crack prevention processing

Foreword

Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other

mixture

but

formation

of

the

in

addition

material

of

quality

brittleness

not

and

all

e

the

concrete

construction

transform

with

oneself,

control

etc.

a

series problem, harden model of in the concrete existence numerous tiny hole, spirit

cave and tiny crack, is exactly because these beginning start blemish of existence just

make the concrete present one some not and all the characteristic of tiny

crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little

bit other use function not a creation to after the concrete be subjected to

lotus carry, difference in temperature etc. function, tiny crack would continuously of

expand

with

connect,

end

formation

we

can

see

without

the

aid

of

instruments

of

macro view the crack be also the crack that the concrete often say in the engineering.

Concrete

building

and

Gou

piece

usually

all

take

sewer

to

make

of,

because

of

crack

of

existence

and

development

usually

make

inner

part

of

reinforcing

bar

etc.

material creation decay, lower reinforced concrete material of loading ability, durable

and anti- Shen ability, influence building of external appearance, service life, severity

will threat arrive people's life and property safety.A lot of all of crash of engineerings

is because of the unsteady development of the crack with the result age

science research with a great deal of of the concrete engineering practice certificate, in

the concrete engineering crack problem is ineluctable, also acceptable in certainly of

the scope just need to adopt valid of measure will it endanger degree control at certain

of scope reinforced concrete norm is also explicit provision:Some structure

at

place

of

dissimilarity

under

the

condition

allow

existence

certain

the

crack

of

at

under

construction

should

as

far

as

possible

adopt

a

valid

measure

control

crack

creation,

make

the

structure

don't

appear

crack

possibly

or

as

far

as

possible decrease crack of amount and width, particularly want

to as far as possible

avoid harmful crack of emergence, insure engineering quality thus.

Concrete crack creation of the reason be a lot of and have already transformed to

cause of crack:Such as temperature variety, constringency, inflation, the asymmetry

sink to sink etc. reason cause of crack;Have outside carry the crack that the function

cause;Protected

environment

not

appropriate

the

crack

etc.

caused

with

chemical

differentiation

to

treat

in

the

actual

engineering,

work°

out

a

problem

according to the actual circumstance.

In the concrete engineering the familiar crack and the prevention

Suo crack and prevention

Stem the Suo crack much appear after the concrete protect be over of a period of

time or concrete sprinkle to build to complete behind of around a the cement

syrup humidity of evaporate would creation stem Suo, and this kind of constringency

is can't Suo crack of the creation be main is because of concrete inside

outside humidity evaporate degree dissimilarity but cause to transform dissimilarity of

result:The

concrete

is

subjected

to

exterior

condition

of

influence,

surface

humidity

loss

lead

quick,

transform

bigger,

inner

part

degree

of

humidity

variety

smaller

transform smaller, bigger surface stem the Suo transform to be subjected to concrete

inner part control, creation more big pull should dint but creation relative

humidity is more low, cement syrup body stem Suo more big, stem the Suo crack be

more easy the Suo crack is much surface parallel lines form or the net

shallow thin crack, width many between 0.05-0.2 mm, the flat surface part much see

in the big physical volume concrete and follow it more in thinner beam plank short to

Suo

crack

usually

the

anti-

Shen

of

influence

concrete,

cause

the

durable of the rust eclipse influence concrete of reinforcing bar, under the function of

the water pressure dint would creation the water power split crack influence concrete

of

loading

dint

etc..Concrete

stem

the

Suo

be

main

with

water

ash

of

the

concrete

ratio,

the

dosage

of

the

composition,

cement

of

cement,

gather

to

anticipate

of

the

dosage of the property and dosage, in addition etc. relevant.

Main prevention measure:While being to choose to use the constringency quantity

smaller cement, general low hot water mire and powder ash from stove cement in the

adoption, lower the dosage of is a concrete of stem the Suo be subjected

to water ash ratio of influence more big, water ash ratio more big, stem Suo more big,

so in the concrete match the ratio the design should as far as possible control good

water

ash

ratio

of

choose

to

use,

the

Chan

add

in

the

meantime

accommodation

of

reduce

is

strict

control

concrete

mix

blend

with

under

construction

of

match

ratio,

use

of

concrete

water

quantity

absolute

can't

big

in

match

ratio

design

give settle of use water is the earlier period which strengthen concrete

to

protect,

and

appropriate

extension

protect

of

concrete

construction

want to be appropriate extension concrete heat preservation to overlay time, and Tu2

Shua

protect

to

is

a

constitution

the

accommodation

is

in

the

concrete

structure of the constringency sew.

Su constringency crack and prevention

Su constringency is the concrete is before condense, surface because of lose water

quicker

but

creation

of

Su

constringency

crack

is

general

at

dry

heat or strong wind the weather appear, crack's much presenting in the center breadth,

both ends be in the centerthin and the length be different, with each other not coherent

r crack general long 20-30 cm, the longer crack can reach to a 2-3

m,

breadth

1-5

creation

of

main

reason

is:The

concrete

is

eventually

almost

having

no

strength

or

strength

before

the

Ning

very

small,

perhaps

concrete

just

eventually Ning but strength very hour, be subjected to heat or compare strong wind

dint

of

influence,

the

concrete

surface

lose

water

to

lead

quick,

result

in

in

the

capillary creation bigger negative press but make a concrete physical volume sharply

constringency,

but

at

this

time

the

strength

of

concrete

again

can't

resist

its

constringency,

therefore

creation

influence

concrete

Su

constringency

open

the

main

factor

of

crack

to

have

water

ash

ratio,

concrete

of

condense

time,

environment temperature, wind velocity, relative humidity...etc..

Main prevention measure:One is choose to use stem the Suo value smaller higher

Huo sour salt of the earlier period strength or common the Huo sour brine is

strict the control water ash ratio, the Chan add to efficiently reduce water to increment

the

collapse

of

concrete

fall

a

degree

and

with

easy,

decrease

cement

and

water

of

is to sprinkle before building concrete, water basic level and template

even

to

soak

is

in

time

to

overlay

the

perhaps

damp

grass

mat

of

the

plastics thin film, hemp slice etc., keep concrete eventually before the Ning surface is

moist, perhaps spray to protect etc. to carry on protect in the concrete is

in

the

heat

and

strong

wind

the

weather

to

want

to

establish

to

hide

sun

and

block

breeze facilities, protect in time.

to sink crack and prevention

The

creation

which

sink

to

sink

crack

is

because

of

the

structure

foundation

soil

quality not and evenly, loose soft or return to fill soil dishonest or soak in water but

result

in

the

asymmetry

sink

to

decline

with

the

result

that;Perhaps

because

of

template just degree shortage, the template propped up to once be apart from big or

prop up bottom loose move etc. to cause, especially at winter, the template prop up at

jelly soil up, jelly the soil turn jelly empress creation asymmetry to sink to decline and

cause concrete structure creation kind crack many is deep enter or pierce

through

sex

crack,

it

alignment

have

something

to

do

with

sinking

to

sink

a

circumstance,

general

follow with

ground

perpendicular

or

present

30

°

s-45

°

Cape

direction development, bigger sink to sink crack, usually have certain of wrong, crack

width

usually

with

sink

to

decline

quantity

direct

proportion

width

under

the

influence

of

temperature

variety

foundation

after

transform

stability sink to sink crack also basic tend in stability.

Main

prevention

measure:One

is

rightness

loose

soft

soil,

return

to

fill

soil

foundation a construction at the upper part structure front should carry on necessity of

Hang solid with is the strength that assurance template is enough and

just

degree,

and

prop

up

firm,

and

make

the

foundation

be

subjected

to

dint

is

keep

concrete

from

sprinkle

infusing

the

foundation

in

the

process

is

soak by is time that template tore down to can't be too early, and want to

notice to dismantle a mold order of is at jelly soil top take to establish

template to notice to adopt certain of prevention measure.

ature crack and prevention

Temperature

crack

much

the

occurrence

is

in

big

surface

or

difference

in

temperature

variety

of

the

physical

volume

concrete

compare

the

earth

area

of

the

concrete

te

after

sprinkling

to

build,

in

the

hardening

the

process,

cement water turn a creation a great deal of of water turn hot, .(be the cement dosage

is in the 350-550 kg/m 3, each sign square the rice concrete will release a calories of

17500-27500

kJ

and

make

concrete

internal

thus

the

temperature

rise

to

reach

to

70

℃

or

so

even

higher)Because

the

physical

volume

of

concrete

be

more

big,

a

great deal of of water turn hot accumulate at the concrete inner part but not easy send

forth, cause inner part the temperature hoick, but the concrete surface spread hot more

quick,

so

formation

inside

outside

of

bigger

difference

in

temperature,

the

bigger

difference in temperature result in inner part and exterior hot the degree of the bulge

cold

Suo

dissimilarity,

make

concrete

surface

creation

certain

of

pull

should

pull should dint exceed the anti- of

concrete pull strength

extreme limit,

concrete surface meeting creation crack, this kind of crack much occurrence after the

concrete under construction the concrete of under construction be difference

in

temperature

variety

more

big,

perhaps

is

a

concrete

to

be

subjected

to

assault

of

cold

wave

etc.,

will

cause

concrete

surface

the

temperature

sharply

descend,

but

creation

constringency,

surface

constringency

of

the

concrete

be

subjected

to

inner

part concrete of control, creation very big of pull should dint but creation crack, this

kind of crack usually just in more shallow scope of the concrete surface creation.

The

alignment

of

the

temperature

crack

usually

none

settle

regulation,

big

area

structure the crack often maneuver interleave;The size bigger structure of the beam

plank

length,

the

crack

run

parallel

with

short

side

more;Thorough

with

pierce

through sex of temperature crack general and short side direction parallelism or close

parallelism,

crack

along

long

side

cent

the

segment

appear,

in

the

center

more