The problem of 21 construction quality with concrete the commonnest project reachs measure of prevention and cure
1 cooperate to compare undesirable
Concrete blends content inattentive, keep difference of ability in swimming, easily secrete water, separation, hard brace up pound close-grained, irrigate the intensity that the short of after building asks.
Reason:
(1) concrete cooperates to compare match without be designed seriously and trying, material dosage scale is undeserved, water ash is compared big, mortar is little, cobble is much.
(2) use raw material does not accord with construction to cooperate to ask than the design, weight of in bags cement insufficient or be affected with damp be affected with damp agglomerates, active is reduced; Aggregate grading is poor, contain impurity much; Water is polluted, or arenaceous stone moisture content was not deducted.
(3) material did not use metage, compare than replacing weight with bulk, with barrow measurement, or although use platform scale metric, metric tool without desired result, the error is very big, material dosage is not accorded with cooperate to compare a requirement.
(4) additive and mix into makings are not strict metage, order of feed in raw material is wrong, concrete not mix is even, cause concrete divide evenly qualitative sex is very poor, function short of asks.
(5) quality management is bad, mix when making, concrete of optional increase and decrease comprises material dosage, make concrete cooperates to compare forbid.
Measure of prevention and cure:
(1) concrete cooperates to match via be designed seriously and trying than answering, make accord with design intensity and performance demand, and the requirement of the workability when construction, do not get experience of optional apply mechanically to cooperate to compare.
(2) ensure quality of concrete raw material, material should via tightened inspection, cement is due quality proves a file, and appropriate is added custodial, in bags cement should selective examination its weight, diameter of arenaceous stone bead, grading, clay content should accord with a requirement; Storage yard should via clearing, prevent fireweed, wood chip, lime, clay to wait sundry interfuse.
(3) strict control concrete cooperates to compare, assure metric and accurate, material all should compare metage by weight, metric tool often should be maintained, school nucleus, every answer answer check 1~2 second.
(4) concrete cooperates to pass an experiment to put forward via lab than answering, press strictly cooperate to compare burden, must not add water at will. Additive should experiment first, control mix into dosage strictly, use by regulations.
(5) concrete mixes make should adjust the amount that add water according to circumstance of water content of border of arenaceous, Shi Shi, make water ash asks than be being accorded with with slump. Concrete construction workability and when protecting ability in swimming to cannot satisfy a requirement, answer to be adjusted through the experiment, must not mix in what already had mixed material is added at will in closing matter.
(6) concrete is carried should use what make oar of concrete separation, leakage or water are broken dispersedly not easily to carry a tool.
2 concrete workability is poor
Mix close matter inattentive and not easy felt, or stick get together muscularity, into the group, irrigate not easily build; Or mix mortar of the cement in closing matter fills the hole between malcontent cobble; Carrying, irrigate in building a course, appear statified separation, not easy concrete brace up pound close-grained.
Reason:
(1) cement intensity grade is chosen undeserved. Design intensity grade when cement intensity grade and concrete than be more than 22 when, cement dosage is too little, concrete mixes close matter inattentive; Design intensity grade when cement intensity grade and concrete than be less than 10 when cement dosage is overmuch, concrete mixes add up to content to stick get together muscularity, into the group, irrigate not easily build.
(2) quality of grading of arenaceous, stone is poor, interstitial rate is old, cooperate to pass than arenaceous rate small, hard concrete brace up pound close-grained.
(3) water ash is bigger than passing with concrete slump, in the mortar when carrying and cobble separation, irrigate in building a course control its uniformity not easily.
(4) metric tool did not examine, the error is bigger, metric system lax or used incorrect metric method, cause cooperate to forbid than carrying out, workability is poor.
(5) concrete agitate time is insufficient, did not mix close even.
(6) the design that cooperates to compare, do not accord with the construction craft requirement to workability.
Measure of prevention and cure:
(1) concrete cooperates to compare design, computation and experiment method, should accord with concerned technology regulation.
(2) pump sends concrete to cooperate to send distance, duct means according to the sort of pump, pump than answering, irrigate build condition of method, climate to wait affirmatory, should accord with following regulation:
1) of clastic rock is the biggest diameter and duct internal diameter than, appropriate is less than or be equal to 1: 3; Pebble appropriate is less than or be equal to is 1: 2.5, those who pass 0.315mm sieve aperture is arenaceous should not less than 15% , the arenaceous control that lead appropriate is in 38%~45% .
2) appropriate of dosage of the smallest cement is 300kg/m3.
3) the slump appropriate of concrete is 100~180mm.
4) mix into of the appropriate inside concrete adds right amount additive.
5) pump sends light aggregate concrete to choose raw material to reach cooperate to compare, answer to decide through the experiment.
(3) should reasonable choose cement intensity grade, those who make cement intensity grade and concrete design intensity grade it is than control between 13~20. When external state of affairs is not done, can adopt mix in concrete the mix into in closing matter adds mixture material (wait like fine coal) or the technical measure such as the agent that decrease water, add up to the workability of content with improving concrete to mix.
(4) raw material is metric should build system of post responsibility, metric method do one's best is handy easy travel, reliable. Of water metric, should make a standard metric pail, additive application small platform balance is metric.
(5) mix in concrete make and irrigate in building a course, should check concrete to comprise the quality of material and dosage by the regulation, every job class should not less than 2.
(6) mixing the dot that make the land and the slump that irrigate the dot that build the ground to check concrete or job are spent, each job class at least 2.
(7) inside class of a job, when if concrete cooperates to be affected than getting outside factor and have,changing, should check in time, adjust.
(8) check concrete agitate time at any time, concrete continuance agitate is the shortest time.
3 additive are used undeserved
Concrete is irrigated after building, local or do not condense for long for the most part sclerotic, or already irrigated the beat since the appearance of concrete structure substance that builds to wrap (common says exterior " blossoms " ) , or concrete mixes add up to content to irrigate the slump before building too small, irrigate not easily build.
Reason:
(1) delay coagulates model the agent that decrease water (the if lignin sulphur is acerbity calcic agent that decrease water) mix into enters an amount overmuch.
(2) enter the additive in concrete in order to do farinaceous mix into (if vitriolic natrium is early strong dose) , fineness do not accord with a requirement, contain did not grind fine grain in great quantities, encounter water to expand, cause concrete surface " to blossom " .
(3) the concrete of mix into additive mixes add up to content to carry park time to grow too, cause loss of slump, consistency too big.
Measure of prevention and cure:
(1) the breed that additive should understand in detail before construction and character, correct and reasonable choose additive breed, its mix into adds a quantity to should decide through the experiment.
(2) the additive that the mix into in concrete uses should sign qualification by relevant specification, accord with construction to ask to just can be used via the experiment.
(3) carry the additive part of one's job of the different breed of the spot, utility is not deposited, appropriate is added custodial, prevent promiscuous or degenerative.
(4) farinaceous additive should hold dry position, prevent be affected with damp be affected with damp to agglomerate. The farinaceous additive that has agglomerated, should stoving is ground fine, after crossing 0.6mm sieve aperture, use.
(5) the concrete that mix into has additive must mix is even, agitate time should be lengthened appropriately.
(6) shorten as far as possible the carriage of concrete of mix into additive and park time, reduce slump loss.
Inadequacy of 4 concrete strength or intensity are inhomogenous, intensity deviation is big
Reason: Concrete mixes it is good to make raw material quality was not controlled, metric and lax case, did not carry out seriously cooperate to compare.
Measure of prevention and cure: Had controlled the quality of all sorts of raw material, should carry out seriously cooperate to compare, the burden of strict raw material is metric.
Concrete of 5 light aggregate mixes agitate closing matter not divide evenly, color is abhorrent
Reason: Agitate time is insufficient.
Measure of prevention and cure: When wanting to assure concrete agitate, agree the enough time of content agitate to mixing.
6 concrete mix slump closing matter is not stable
Reason: Water consumption control is not accurate, the change of the moisture content in aggregate of degree of finish determines not in time, adjust water consumption not in time. It is to use water next metric not accurate, water dosage how many.
Measure of prevention and cure: When concrete agitate strict and metric, determine in time the change of the moisture content in aggregate of degree of finish, adjust water consumption.
7 concrete construction seams a setting the position, form and juncture processing are non-standard
Reason: Concrete construction seams a setting to did not ask to undertake deciding according to standard or design beforehand, take place at will; Construction is seamed processing does not have special processing program or have technical put all one's card on the table.
Measure of prevention and cure: Concrete is irrigated before building, undertake deciding construction seams the position according to standard or design requirement above all; Construction seams processing to had done special processing plan or have technical put all one's card on the table.
8 divide evenly pledge the gender is differred, intensity short of asks, average of compressive strength of concrete test block designs intensity grade, or exorbitant or cost of intensity of individual test block is too low in approving concrete together, appear unusual.
Reason:
(1) cement expires or be affected with damp be affected with damp, active is reduced; Grading of aggregate of arenaceous, stone is bad, interstitial rate is old, clay content and impurity exceed a regulation, have aspic piece interfuse; Additive is used undeserved, mix into amount is not exact.
(2) concrete cooperates to compare undeserved, metric forbid, in bags cement is owed heavy, metrological implement is out of order, water is added at will in construction, did not deduct the water content of arenaceous, stone, make water ash is compared increase with slump.
(3) order of concrete feed in raw material is conversed, agitate time is insufficient, mix close not divide evenly.
(4) construction of wintry period low temperature, did not take heat preservation step, form removal is premature, concrete is inchoate suffer aspic.
(5) concrete test block is done not have representative, try a model custodial not to be pooh-poohed, concrete test block is made not brace up pound close-grained, conserve misgovern, conserve condition does not accord with a requirement; When be the same as conditional conserve, inchoate dehydrate, suffer aspic or suffer outside force loss.
(6) concrete mixes agitate closing matter is over to irrigate build ending continuance time to grow too, brace up pound excessive, conserve is poor, make concrete strength gets loss.
Measure of prevention and cure:
(1) cement is due outgoing quality certificate of approval, should strengthen cement to work surely, the requirement is new without agglomerate, expire cement is used via the ability after the experiment is eligible. When having doubt to cement quality, should have re-check test, the intensity grade that presses test result is used.
(2) diameter of bead of arenaceous, cobble, grading, clay content should accord with a requirement.
(3) strict control concrete cooperates to compare, assure metric and accurate, measure moisture content of arenaceous, stone in time to deduct water consumption.
(4) concrete should press ordinal feed in raw material, mix make, make sure agitate time is mixed mix divide evenly.
(5) aspic period construction should spend a circumstance according to environmental big air temperature, those who keep certain irrigate temperature, the heat preservation that makes good concrete structure seriously and measure lukewarm job, prevent concrete inchoate suffer aspic. It is below wintry period condition the concrete of conserve, sufferring before freezing, the concrete that silicate or common silicate cement make up, should achieve the 30% above that design intensity grade, the concrete that scoria silicate cement makes up, should achieve 40% above, but the concrete under C10 and C10 is not gotten under 5 MPa.
(6) check and accept normative requirement to make concrete test block seriously by construction, strengthen the management to test block and conserve.
Face of 9 beehive hemp
Reason: Concrete leaves makings heavy panel, brace up pound disloyal or leakage brace up, pattern plate has aperture to make grout prediction of a person's luck in a given year, reinforcing steel bar is closer and concrete slump passes small or cobble is too big, pattern plate of ministry of column, the foot of a wall has crack, the mortar in concrete of as a result flushs from bottom and cause.
Measure of prevention and cure: Next makings ply reach concrete brace up pound should accord with relevant provision. Decide concrete aggregate norms according to span of reinforcing steel bar, had done cooperate to compare. Processing of pattern plate aperture serves as a working procedure, should block up severe. Fence post concrete is irrigated what deserve to compare together with concrete is use first before building spread an oar without cobble mortar not less than 50 Mm are thick.
10 dew muscle
Reason: Too big, leakage puts displacement of space block of reinforcing steel bar, span, reinforcing steel bar is clingy pattern plate, cause dew veins that stand out under the skin, or bridge, board bottom brace up pound disloyal, appear possibly also dew muscle.
Measure of prevention and cure: Space block of reinforcing steel bar has been filled up by the regulation, position of colligation of reinforcing steel bar wants guarantee against displacement. Concrete brace up pound should prevent to leak brace up or over- brace up.
11 concrete hemp face, felt
Reason: Form removal premature or leakage of pattern plate surface brushs interleaving agent or pattern plate is wet and insufficient, easy conglutinate of concrete of component part surface causes hemp face desquamate on pattern plate.
Measure of prevention and cure: When raising a standard, should make sure cleanness of pattern plate surface is clean, brush good interleaving agent. Concrete form removal undertakes strictly by formulary time.
12 hole
Reason: It is the place concrete with closer reinforcing steel bar is blocked, without brace up pound continue to irrigate build superstratum concrete.
Measure of prevention and cure: The place with closer reinforcing steel bar uses small diameter brace up dolly, prevent coagulation soil temperature brace up.
13 aperture and slag inclusion layer
Reason: Construction is seamed place is sundry clear ungodliness or did not irrigate the reason such as bottom oar, layer of easy gap, slag inclusion.
Measure of prevention and cure: Concrete raises a model to reach irrigate place concrete should seam construction before building or inside pattern plate sundry clear clean, fence post concrete is irrigated what deserve to compare together with concrete is use first before building spread an oar without cobble mortar not less than 50mm are thick.
Sodden root of 14 walls body
Reason: Before raising a standard not the mouth below every edge pattern plate not make level, the mouth below pattern plate is not close, oar of coagulation soil temperature.
Measure of prevention and cure: Before raising a standard, in every edge pattern plate issues a mouth to apply make level layer, make sure pattern plate plays buccal rigor. Wall body concrete is irrigated before building, irrigate equably first build 5cm thick mortar or decrease cobble concrete. Concrete slump wants to be controlled strictly, prevent concrete separation, bottom brace up pound should operate seriously.
Oar of muscle of beehive of 15 concrete surface, dew, hole, slag inclusion, sodden root, leakage is serious; Mouth of a cave is out of shape, edge damage drops horn. Form removal is early, do not undertake conserve by the regulation; Exterior break
Reason: Inside pattern plate sundry clear sordid, pattern plate consolidate is not firm, juncture is not close, form removal is premature; Concrete is irrigated build hourglass brace up or brace up pound not close-grained, owe brace up. Wooden pattern plate waters not adequately wet or wet insufficient, concrete irrigates the conserve after building bad, cause dehydration, intensity is low, or pattern plate is bibulous expand edge horn rip, when form removal, edges and corners is stuck; Microtherm construction demolishs flank blame prematurely to bearing pattern plate; When form removal, edge horn gets outside force or the clog is bumped, or protection is bad, edges and corners is touched; Pattern plate did not besmear brush interleaving agent, or besmear is brushed not all.
Measure of prevention and cure: Wooden pattern plate is being irrigated before building concrete, answer sufficient and wet, concrete is irrigated guarantee against answers to leak when building brace up, owe brace up or over- brace up. Concrete is irrigated conserve should water seriously after building, concrete form removal should concern a provision, the attention when form removal protects edges and corners, avoid to had exerted oneself to do sth. fierce previous; Swing pattern plate, prevent to bump edges and corners, when carrying, it is good that finished product this world horn uses the protection such as careless bag, lest touch caustic.
Board face chap forms 16 cast-in-place even edge board thick be well versed in
Reason:
(1) concrete deserves to compare arenaceous rate big, concrete systole is out of shape big.
(2) concrete is irrigated after building, did not press a demand seasonable conserve, make concrete dehydrates drying shrinkage forms break.
(3) board face caboodle carries concrete overweighted, or load is inhomogenous, make concrete gets concussion load even.
Measure of prevention and cure:
(1) concrete matchs more reasonable than wanting, prevent to appear arenaceous rate causes concrete greatly too serious systole is out of shape.
(2) concrete is irrigated after building, should water in time by the requirement or enclothe plastic cloth conserve, prevent concrete to dehydrate drying shrinkage forms break.
(3) concrete board scale load should undertake checking computations according to designing load, must not carry in board face caboodle at will, should notice board scale load wants even, load of forbidden occurrence concussion.
Component part of 17 concrete construction is irrigated after building drawing of patterns, exterior crisp pine falls off
Reason:
(1) wooden pattern plate did not water drenched or wet insufficient, the moisture of to hydrate of cement of concrete surface layer is sucked, cause concrete dehydrate crisp pine, fall off.
(2) burning hot blow the day is irrigated build concrete, not proper protecting cover waters after drawing of patterns conserve, create concrete surface layer fast dehydrate, produce crisp pine.
(3) wintry period low temperature irrigates built concrete, irrigate build temperature low, did not take heat preservation step, cause concrete surface to suffer aspic, crisp pine, fall off.
Measure of prevention and cure:
(1) wooden pattern plate should be irrigated in concrete before building water adequately drenched.
(2) burning hot blow the day is irrigated build concrete, answer after drawing of patterns instantly proper protecting cover waters conserve, avoid concrete surface layer fast dehydrate, produce crisp pine.
(3) wintry period low temperature irrigates built concrete, should adopt measure to raise concrete to enter modular temperature, take heat preservation step, avoid concrete surface to suffer aspic.
Dimension of geometry of connect of 18 bridge column is irregular; Column wrong stage leaves on
Reason: Pattern plate of bridge column connect is broken go all out, did not undertake special pattern plate is designed, consolidate is not firm. Fixed position of fluctuation floor axes puts a line to have an error.
Measure of prevention and cure: Pattern plate of bridge column connect should undertake special pattern plate is designed, use finalize the design pattern plate, forbidden broken go all out, and consolidate firm. Floor puts a line to answer different layer have review a case in which a death sentence has been passed by a lower court, person specially assigned for a task is in charge of,
Displacement of 19 sectional dimension, verticality, flatness, axes exceeds allow to had been been worth big
Reason:
(1) concrete is irrigated after building, the surface is patted with shovel only smooth, did not press light with float make level.
(2) pattern plate not bearing is on hard earth layer, or bearing face is insufficient, prop up become loose, earthy layer is soggy, cause irrigate newly build concrete happen when inchoate conserve inhomogenous sink.
(3) the person goes up when concrete strength did not achieve 1.2 MPa, make the surface appears uneven or moulage.
Measure of prevention and cure:
(1) concrete is irrigated after building control a mark strictly by the level or play a line to use float make level, press light, conserve waters after coagulating eventually.
(2) pattern plate, prop up due and enough bear the weight of force, stiffness, stability, pillar and prop up must bearing is on solid earthy layer, have ample bearing area, prevent soggy, sink in order to make sure the structure does not produce excessive.
(3) concrete is irrigated in building a course, often should check pattern plate and the circumstance that prop up, if have,become loose be out of shape, should stop to irrigate instantly build, be in consolidate of the nap before concrete condenses is good.
(4) after concrete strength achieves 1.2MPa, just can go up person operation.
20 displacement, tilt
Foundation, column, wall and bury a central line to be opposite beforehand fixed position axes, produce a direction or two directional deflection, or generation of verticality of column, wall is certain deflective (say to tilt) , its displacement or tilt the value all exceeds tolerance value.
Reason:
(1) pattern plate is raised set not firm or diagonal brace raises a top to be on loose foundation, concrete brace up displacement arises when pounding or tilt. If cup mouth uses method of pensile condole model, if bottom, able to read aloud fluently is secured not firm, the displacement with constant larger generation or tilt.
(2) pattern plate of mouth of a cave reachs the door to be buried beforehand fixed not firm, concrete is irrigated build, brace up pound a method undeserved, cause the door mouth of a cave and bury the displacement with a larger generation beforehand.
(3) put a line to appear bigger error, was not checked seriously and corrective, or did not discover in time and correct, cause axes to accumulate an error big, or search without serious plumb-line when pattern plate perch straight, cause structural happening askew.
Measure of prevention and cure:
(1) pattern plate should secure firm, be like to part of mouth of independent base cup when introducing condole model, want to adopt measure to will a string of 1 the model has been secured, must not become loose, the horizontal displacement with larger generation is not sent when be being built with maintaining pattern plate to be irrigated in concrete.
(2) pattern plate should flat-fell seam is close, raise a top to be on solid foundation, without become loose; Bolt should originally closely reliable, elevation, dimension should accord with a requirement, should check a nucleus to be opposite, displacement happens in order to avoid construction in the process or tilt.
(3) pattern plate of door mouth of a cave and all sorts of bury beforehand should raise set firm, make sure the position and level are exact, after the examination is eligible, ability is irrigated build concrete.
(4) cast-in-place frame column group pattern plate should be controlled all pull a line to be stabilized in order to maintain; Cast-in-place column is prefab bridge construction, column pattern plate all around should raise establish diagonal brace or inclined drag link, use flange bolt to adjust, in order to assure its verticality.
(5) measure line of the position that put a line to want to play accurate, serious plumb-line searchs straight, adjust an error in time, accumulate in order to eliminate an error, and microscope, check, make sure construction error does not exceed tolerance value.
(6) irrigate when building concrete, prevent to pound a doorway pattern plate and bury beforehand, hold to door mouth of a cave semmetry of two side concrete undertakes irrigating building mixing equably brace up pound. Column is irrigated when building concrete, every discharge post bottom to be undertaken orderly by the semmetry inside extroversion, must not advance to another end by one aspect of the matter, with preventing column pattern plate happening tilts. Before coagulating at the beginning of independent column concrete, answer its verticality to undertake school nucleus, if have,deviation should be adjusted in time.
(7) brace up when pounding concrete, must not pound oscillatory reinforcing steel bar, pattern plate to reach bury beforehand, generation is out of shape or bury a displacement in order to prevent pattern plate beforehand or fall off.
21 pattern plate go up model, explode model
Bilge model, explode modular phenomenon produces an account
Problem of pattern plate of pattern plate respect, include quality of pattern plate itself poor, intensity is insufficient or pattern plate material is qualitative choose undeserved etc. Pattern plate supports an issue, include to prop up the not firm, check the number that prop up to measure the insufficient, means that prop up to choose undeserved etc. Problem of pattern plate join, include undeserved to pulling join bolt amount and span etc. The member that construction personnel problem includes construction person operates undeserved, operation not strong, technology closes heart of not serious, responsibility nevertheless etc. Manage respect government not to reach the designated position, constituent not do one's best, system and measure are not full, executive examination is insufficient. Administrator is irrigated to old standard concrete build board medium detail is not familiar, cooperate between team and group not tacit etc.
Bilge model, explode modular processing measure and method bilge in the light of above generation model, explode modular reason, use the following kinds of methods and measure to decrease bilge model and explode the happening of modular phenomenon. When pattern plate is calculated, divide calculate by formula beyond, want to try to adjust according to particular case, because pattern plate computation does not decide the element is very much, like concrete slump, temperature, irrigate speed, brace up inaccuracy decides pound a method to wait, should give when computation consideration. Bolt respect, bolt is defeated happen in screw cap to fall off more, the screw cap that is like a bolt falls off invalidation, the bolt that brings about periphery suffers force to increase as a result to be defeated, ordinal influence more bolt, produce whole to explode thereby model, such circumstance can use double nut, or the bolt that suggests production takes peg prevents screw cap to fall off. Because concrete lateral pressure is to show a triangle to distributing, pull rod wants according to fall to go up closely scanty principle will install, the problem that with alleviating amount of pattern plate pull rod is not worth. The firm side that pattern plate supports, key examination suffers force staff and fore-and-aft the firm sex that prop up. When beat concrete, ask to expect below even semmetry, strict control irrigates height, especially pattern plate of mouth of door an opening in a wall two side, should assure concrete already brace up pound close-grained, it is beyond the mark to should prevent again brace up pound cause pattern plate to be out of shape. When using construction of wooden pattern plate, plywood pattern plate, after checking and accept qualification, want to be irrigated in time build, prevent insolate drench happening is out of shape. Repeat use pattern plate must close check rehabilitate. Personnel of strict requirement operation controls good concrete brace up pounded insertion deepness, must not pass deep. Already brace up pounded place must not insert vibration to hold in both hands again brace up pound, avoid to explode the model arises now.
