Precast News From China
The slump of concrete mainly refers to its plasticizing and pumpability properties.
The factors that affect the slump of concrete mainly include changes in gradation, moisture content, weighing deviation of the scale, dosage of additives, and the temperature of cement, which are easily overlooked.
Slump refers to the workability of concrete, specifically ensuring the normal progress of construction, including its water retention, flowability, and cohesiveness.
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Concrete material is the most widely used material in industrial and civil construction, as well as transportation, water conservancy, municipal and other construction projects.
With the development of society, the use of commercial concrete in construction is becoming increasingly widespread, and the requirements for the strength and other performance of concrete itself are also increasing.
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The design of concrete production and application involves several important aspects such as concrete raw materials, production, transportation, vibration, and concrete curing.
Only by coordinating these aspects can a suitable mix proportion be formulated.
Optimizing the concrete mix ratio parameters according to different situations is a prerequisite for ensuring the quality of concrete, and it is also the basis and means for adjusting the mix ratio.
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In the field of construction engineering, with the arrival of winter, the continuous decline in temperature has brought many severe challenges to concrete construction.
Concrete, as a key material for building structures, requires extra caution in its preparation and construction process during winter, as even a slight mistake may lead to quality issues.
Therefore, in order to ensure the quality of the project, we must have a deep understanding and strictly implement the technical points of winter concrete construction.
We hereby submit this detailed technical disclosure and winter construction strategy for the construction and supervision units.
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Many concrete slabs have just been poured, and soon after, dense, spider like web like cracks appear on the surface, which are often attributed to problems caused by “untimely maintenance”.
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To solve the problems in the application of orthogonal anisotropic steel plate ultra-high performance concrete composite bridge deck pavement in China, a survey was conducted on the current status of ultra-high performance concrete composite bridge deck pavement technology at home and abroad through literature review, actual bridge investigation, and on-site testing.
Field investigations were also conducted on the service conditions of 9 representative composite bridge deck pavements in China.
The results show that: 1) China’s steel UHPC composite bridge deck has differences in materials and structures compared to the Netherlands and Japan, mainly due to the dense arrangement of shear studs between the UHPC layer and the steel bridge deck; 2) At present, the UHPC composite bridge deck pavement in China mainly suffers from diseases such as mixture segregation, pavement cracking, rutting and displacement, and expansion joint cracking.
Subsequent research should focus on the bonding between UHPC and the wear layer, the anti rutting and anti cracking of asphalt wear layer, and the prevention of mixture segregation.
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At present, in the process of compounding production, only simple production techniques are mastered or the improvement of concrete properties by admixture products is pursued unilaterally, but the influence of some components and addition amounts in compounding on concrete strength and durability is ignored.
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Preloading is used to test the strength, stiffness, and stability of the 0 # block support of prestressed concrete continuous beams.
The preloading of the 0 # block support for prestressed concrete continuous beams is an essential key process and the first step in the safe construction of prestressed concrete continuous beams.
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The structure of various parts of a certain large-scale water conservancy hub project is mostly large in volume.
We mainly focus on the common quality problems and prevention measures of large volume concrete to ensure the high quality of the project.
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Strictly follow the concrete mix proportion sheet provided by the laboratory and approved by the supervisor for batching, and it is strictly prohibited to change the concrete mix proportion without authorization.
The construction unit must use accurate weighing equipment for production and regularly check the weighing equipment according to the instructions of the supervisor.
We insist on weighing each plate of sand and gravel, and do not advocate the volumetric method of marking with small carts.
In addition, regular spot checks should be conducted on mixing time, feeding sequence, concrete slump, and whether the concrete is segregated.
In larger projects, construction units should use computer-measured mixing plants to reduce human factors and ensure the design strength of concrete.
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