| Customization: | Available |
|---|---|
| Function: | Strengthen |
| Prouduct Time: | 15-20days |
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Ultra High Performance Concrete (UHPC) Premix PF-UHPC
Color characteristics: Grey
Executive standard: T/CBMFXX/T/CCPAXX-202X (this standard number)
Note 1: The characteristics of UHPC contraction: the early stage (0~7d) develops rapidly, accounting for 61.3%~86.5% of the total contraction, and the middle stage (7~28d) develops slowly, accounting for 13.5%~27.9% of the total contraction Stablize. UHPC is dominated by autogenous shrinkage, accounting for 78.6% to 90.0% of the total shrinkage, which is the main cause of early cracking. The start time of the shrinkage test can be taken as 1d (24h) after the specimen is formed, and the end time can be taken as 90d or 120d. (Excerpt from reference: Chen Baochun et al. "Summary of ultra-high performance concrete shrinkage", Journal of Transportation Engineering, February 2018)
Note 2: See Appendix C "Ultimate value of shrinkage strain" for the shrinkage value usually considered in the design. Low-shrinkage UHPC needs to be specially formulated, and the specific shrinkage technical requirements need to be negotiated between the supplier and the buyer.
Under the conditions of base water-material ratio/base fiber and dosage:
-Standard thermal curing 28d hardening performance: tensile strength 10.8MPa, compressive strength 140MPa
-Development characteristics of standard maintenance compressive performance: 1d72MPa, 28d140MPa, etc. (or expressed in the form of age-compressive strength development curve, which may include strength development curves under different temperature conditions)
Elastic modulus: standard maintenance 50MPa
Note 1: Other properties required by users can be provided, such as bending resistance, thermal expansion coefficient, etc.
Note 2: The impermeability performance of the fiber-free matrix (the PM-UHPC product used) reflects the overall durability of UHPC. In GB/T 50476 "Concrete
It is used in all categories and grades of exposure environments defined in the Code for Design of Structural Durability, and does not need to test the durability items of other ordinary concrete such as frost resistance and sulfate corrosion resistance. The UD20 impermeability grade is applicable to the A and B environmental grades specified in GB/T 50476; the UDO2 impermeability grade is applicable to all other environmental grades (C, D, E and F) specified in GB/T 50476. If it is used in a heavy chemical corrosion environment (not in the environmental category and level defined in GB/T 50476), the applicability of UHPC needs to be evaluated or surface protection is required
Note 3: UHPC is required to have excellent wear resistance, high temperature resistance (fire resistance), impact resistance or anti-explosion performance, and UHPC needs to be specially prepared and evaluated according to application requirements.
| Note 1: The measurement deviation of water should be less than 1%, and the measurement deviation of admixture and fiber should be less than 2%. Decreasing the water-to-material ratio can reduce the workability level of the mixture and improve the matrix strength (in the state of being able to pour and compact well) Note 2: The air content of the fresh mixture, UHPC is usually in the range of 3% to 6%. It is recommended to check the air content of the fresh mixture. If it is too high, the reason should be analyzed and checked to avoid significantly affecting the hardening performance. Note 3: To measure the expansion degree of UF700 and UP800 grades, it is advisable to measure the T500 time (the time when the expansion diameter reaches 500mm) at the same time to evaluate the viscosity level of the mixture. For UF700 and UF800 grades, the T500 time is less than 10 seconds and 7 seconds respectively, which can be regarded as low viscosity mixture. Note 4: Appropriate UHPC fresh workability level means that it is easy to pour and compact, and at the same time can obtain good fiber distribution uniformity. It needs to be selected in combination with the methods and conditions of prefabricated or cast-in-place construction, as well as the types and specifications of fibers contained in UHPC. Expansion UF800 grade mixture can be self-flowing and self-compacting, and is suitable for pouring structures whose top surface (free surface) is a horizontal surface or the top surface is covered with formwork. Contains steel fibers, not suitable for vibration, to prevent steel fibers from settling. Fiber directionality is affected by factors such as flow direction and formwork wall effect. Spread UF700 and UF600 grade mixtures are suitable for pouring structures where the top surface (free surface) is horizontal or the slope is small or the top surface is covered with formwork. Density, usually by means of tamping, low-frequency vibration and other methods to ensure that the corners or densely populated places are dense. Contains steel fiber, not suitable for high-frequency vibration. c) For structures with a certain slope on the pouring top surface (free surface) and no template coverage, as well as spraying construction, extrusion molding, etc., the mixture needs to have a certain consistency, and it needs to be combined with pouring and dense construction methods to test to determine the appropriate workability grade (consistency level). Note 5: In application, changes in ambient temperature and loss of moisture in the mixture will lead to changes in workability maintenance time and setting time, and tests under corresponding conditions are required to determine whether the pouring molding and construction requirements are met. Rapidly setting and hardening UHPC needs to be specially formulated, and the specific technical requirements need to be negotiated between the supplier and the buyer to determine the setting time and strength development requirements for the environmental conditions of use. |
When using ultra-high-performance concrete matrix premix to produce ultra-high-performance concrete and pouring construction, operators should wear industrial-grade N95 masks, goggles, safety shoes, hard hats, and overalls to prevent inhalation of dust and prevent fibers from harming the human body.
The ultra-high performance concrete matrix premix of ultra-high performance concrete is usually used in small bags (net weight 50kg) or large bags (net weight1000kg),
Each independent package should be put into the mixer in its entirety (the ultra-high-performance concrete matrix premix containing aggregate is affected by transportation bumps, etc.
segregation of coarse and fine particles may occur). In order to avoid dismantling the bag and using it in batches, the appropriate packaging specification can be determined according to the characteristics of the project, the minimum amount of use at one time, and the amount of mixing at one time.
Maintenance advice
Basic principles of good maintenance: Formed test pieces, prefabricated production components and cast-in-place construction processes and after 7 days, superelevation should be avoided as much as possible.
Performance concrete loses moisture. After the surface is plastered, the exposed surface of ultra-high performance concrete should be covered with plastic film or curing agent immediately to prevent water loss through evaporation. For large-scale construction, especially when exposed to wind and sun, the surface should be wiped for a period of time, and then cured for a period of time, to avoid the surface being exposed for too long after the surface is wiped.
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