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Some Reasons about Concrete Quality Problems
At the time of operation many concrete construction workers will encounter many difficult issues and do not know how to judge resolved. Today, Hmaomei Machinery will analysis on a number of possible concrete quality problems.
First, analysis the reason of concrete surface bubbles
1. Case reproduce: When pouring the first floor of the building beams, plates, columns, when, after the discovery of concrete form removal of parts of the wall panels and columns appear in many different sizes of bubbles, although the strength of concrete can be meet the design requirements, but bubbles affect the overall results.
(2) At the time of construction workers pouring concrete vibration time is short, do not grasp the vibrator should "push-pull-slow" to carry out concrete vibrators;
(3) Concrete pouring feeding excessive number of bubbles floating less than the concrete surface.
(1) Re-adjust the recipe additives to reduce air-entraining component, appropriate to add anti-foaming agent;
(2) Concrete construction personnel training.
Second, analysis the reason of concrete cracks appear
1. Case reproduce: When an engineering team on floor 5 layer pouring operation coincided with the spring, wind up to level 5 to 6, dry climate. The next day the roof construction a large area concrete cracks, as some crack through the cracks, but the strength of concrete can meet the design requirements.
(1) Due to the construction of a dry climate, wind, concrete roof surface moisture can easily evaporate;
(2) the construction side have been pouring concrete without any moisture conservation measures, resulting in rapid evaporation of moisture concrete, the emergence of shrinkage cracks.
(1) shall strengthen the construction of concrete understanding of the need to strengthen early moisture conservation concrete. Usually you can use a plastic film moisture conservation. After pouring the concrete method is vibrated, concrete response immediately be covered with plastic film to prevent water evaporation caused by concrete shrinkage cracks appear, usually conservation 12d ~ 24d.
(2) When the weather has changed, mixing station should contact or communication with the construction side, causing the construction side note, to avoid quality accidents;
Third, change the setting time of concrete occur Causes
1. Case reproduce: Construction of an engineering team in early March, the temperature in March is very unstable, cool wind construction, projecting to minus 10 degrees, more than 20 hours does not lead to concrete solidification phenomena.
2. Analysis: inappropriate choice of pumping admixture. The usual minimum temperature above 0 ℃ pumping agent can be selected without antifreeze component. When the temperature dips construction, pumping agent should be used with antifreeze ingredient.
(1) Ready Mixed Concrete Batching Plant should be equipped with two or more admixtures reserve tanks were fitted with different types of admixtures to prevent the exchange of the season when the temperature is unstable, to be selected according to specific circumstances, to prevent the production of concrete mixing plants appear clotting time the problem of excessive deviation occurs;
(2) the exchange of seasonal temperatures less stable situation, should use Portland cement or ordinary portland cement