tory burch shoes The level of pumping concrete str

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<P class = MsoNormal style = : 10.5pt Thus, not only cause the amount of fly ash into inaccurate and likely to cause confusion in the feed in order to make concrete mixing the feed required by the order - fly ash should be synchronized with the cement, admixtures should lag behind the water and cement, it is difficult guaranteed. <P class=MsoNormal style=in bad traffic environment, transport long distances, making the transport duration beyond the initial setting time of concrete one-half, or more than the state standards, resulting in great loss of concrete slump and casting difficulties, or even result in follow-up processes impossible.

things in the world, where there is a benefit, is also there will be a disadvantage. Through years of construction and supervision practices, combined with the level of structure prone to cracking phenomenon, the raw materials from pumping concrete,[link widoczny dla zalogowanych], mixing ratio, mixing,[link widoczny dla zalogowanych], transportation, pumping, pouring,[link widoczny dla zalogowanych], and to start domestic production conditions, to analyze the causes of cracks and to find solutions to problems,[link widoczny dla zalogowanych], and achieved good results for the peer reference, Fu Zheng. Chinese papers League finishing.

<P class=MsoNormal style=c), pumping and pouring <P class = MsoNormal style = pt

<P class=MsoNormal style=the current supply of pumping concrete coarse aggregate existing screening unqualified, grading unreasonable, excessive size of coarse aggregate and needles, too many other issues sheet aggregate, resulting in a pipeline blockage. <P class=MsoNormal style=, horizontal structure, easy to produce cracks of
<P class=MsoNormal style=agent use, make the request by the use of modified concrete. For example, the use of water reducer, can greatly reduce the water-cement ratio and increase strength, improve the mixture of fast and easy, making the slump increased. Retarder use, for the Concrete to the mix, transport, provide the possibility of casting. <P class=MsoNormal style=II), Concrete mixing and delivery

<P class=MsoNormal style=c), quality awareness apathy, inadequate measures to control, manage confusion is the external cause of cracks. <P class=MsoNormal style=agent content of the out of control, or mixing uneven, causing solidification of concrete is not a long time, resulting in the gradual evaporation of moisture in the concrete, the cement of the gel gradually drying shrinkage, which led to the shrinkage cracks in concrete. This concrete, like a rubber-like, under the construction loads generated by plastic deformation, the formation of cracks, it is difficult to heal.
<P class=MsoNormal style=to improve the pumpability of concrete, in addition to provisions in the sand fine aggregate is preferred, but also through the 0.315mm sieve sand content shall not be less than 15% of the strict requirements, so that the ultra-fine sand content, compared with ordinary concrete increased. <P class=MsoNormal style=provisions of the sand concrete delivery rate between 38% -45% compared to using ordinary methods of concrete construction sand rate increased by 4% -5%, so that the amount of sand in the coarse and fine aggregate proportion of the total increase large.
<P class=MsoNormal style=fly ash in concrete pumping, not only can reduce the amount of cement, and which contains silica and alumina, alkaline substances in the cement, come. <P class=MsoNormal style=pumping technology to meet the requirements of the design of concrete's slump values, is highly correlated with the pumping. The higher the altitude, the greater the slump, slump large, means that the increase in water consumption or water reducer admixture.
Keywords: crack incident handling
<P class=MsoNormal style=, the characteristics of the pumping of concrete: <P class = MsoNormal style = size: 10.5pt ; mso-char-indent-size: 10.5pt under pressure in the pump, the characteristics of the pipeline to its cement content, slump, sand ratio has done a special treatment, to meet the pumping requirements.

<P class = MsoNormal style = : 10.5pt <P class=MsoNormal style=The most striking features of the structure is much smaller than the thickness of the length and width of the surface area exposed in the air than other structures. The resulting structure Tongjiao note of this, the process of condensation, evaporation of water area, particularly in high temperature, wind, relative humidity, the weather, the small, concrete surface, rapid evaporation of the water easily, large volume shrinkage, and concrete humidity changes within the small volume change is also smaller, so the surface of concrete shrinkage by internal constraints, there tensile stress, causing cracking of concrete surface, resulting in shrinkage cracks.
<P class=MsoNormal style=II), pumping technology and process requirements, making the pumping small size of coarse aggregate concrete, sand ratio is too large, particularly to increase the amount of fine sand, fly ash and admixtures, is caused by pumping Concrete underlying causes of the early cracks: <P class = MsoNormal style = 10.5pt , fine sand under the action of buoyancy, floating on the surface, with the cement hydration reaction, the shrinkage stress occurs, is much larger than the cracking strength of concrete at this time, resulting in surface cracking, shrinkage cracks.

The level of pumping concrete structure with cracks in the surface of the causes and prevention measures

Abstract: As in concrete admixtures and fly ash mixed with the .

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