Fine aggregate concrete pump for pumping concrete requirements Fine aggregate concrete pump for pumping concrete requirements are the following, today Xiaobian done a detailed analysis, Welcome. First, cement
1, the pumping pressure of cement in the concrete pumping process by which liquid mass transfer. Liquid substances carrying a solid phase material to move together in order to complete the pumping. Of the cement has two aspects: First cementation, the concrete maintains a solid phase material is surrounded by the liquid state of matter in the pumping; Second, the lubricating effect of the concrete pump with mechanical mini concrete mixer trucks price parts, pipelines and concrete reduced internal friction and has good mobility. 2, of cement concrete pumping performance cement should have good water retention properties of the concrete during pumping is not easy bleeding. Ordinary portland cement, pozzolan cement better water retention, and slag cement water retention is poor, such as using it to pump concrete mixing, the need to increase the amount of cement, and increase the rate or add some sand fly, use more low slump. When using fly ash cement, concrete liquidity is better, but early bleeding of large, low slump is appropriate and possible continuous pumping. 3, the amount of cement to the appropriate amount of cement. If the amount of cement shortage, pumping volume efficiency decreases significantly increase transport resistance, and this concrete water retention is poor, easy bleeding, segregation and clogging; if excessive use of cement, concrete viscosity will be too large, increasing resistance delivery Great, but little change in pumping volume efficiency. In the same diameter, graded gravel aggregate and gravel aggregate compared to a large amount of cement gravel concrete. For fine aggregate, the use of artificial broken sand more than the natural sand with cement. The smaller the diameter, the longer the pipe, the flow of concrete requirements, lubricity, higher water retention, so the amount of cement should be increased. As aggregate gradation appropriate maximum aggregate size is bigger, the less amount of cement: But when the aggregate size over 30 mm, oversized aggregate would undermine the continuity of the concrete, grout is difficult to aggregate these fully inclusive, it can not reduce the amount of cement. Fine aggregate fines smaller than 0.2 mm in diameter also plays a role similar to cement. But these fines to have a certain proportion, if its content is less than, or the average particle size is too small, cement consumption will also increase. If the pumping of lightweight aggregate concrete, the cement dosage should be increased. This is due to the porous lightweight aggregate having a high pressure water, drainage characteristics of pressure when pumping tends to become dry and hard concrete and easy Germany concrete pumps manufacturer segregation. Therefore, there should be more lightweight aggregate concrete slurry, cement content of not less than 340kg / m 3.
Second, the aggregate
1, fine aggregate, fine aggregate can be divided into river sand, sea sand, mountain sand according to their origin, artificial broken sand. The former can adopt concrete pump better; artificial sand surface roughness, sand bad shape, need to join part of the natural sand to improve its ratio of features, but the artificial sand better water retention, reducing bleeding segregation phenomenon of the concrete. The fines according to the size of the average particle size can be divided into three types of coarse sand in the sand. Preparation of concrete with sand pumpability best, an average particle size of 0.25-0.3 mm. The average particle size is too small (ie sand too) is not good, it will increase the amount of water and cement concrete. In terms of sand fineness modulus FM measure, FM values between 2.4-3.0 fine aggregate particle size that is required to meet the pumping. Pumping concrete, fine aggregate material with coarse aggregate porosity have a great relationship. Cement gap must be filled with coarse aggregate, less than the rate of sand, cement gap to be filled, will increase the amount of cement, aggregate otherwise easy segregation; if the sand ratio is too large, cement sand to fill the gap, the amount of cement should be increased , otherwise it would cement mortar lubrication greatly reduced, significantly increase pumping resistance, so under certain conditions, have an optimal sand ratio. Such as coarse aggregate with the management, the maximum aggregate size larger optimal sand ratio values lower. Rates with an average particle size of sand or sand Hot selling mini concrete mixer trucks for sale from China fineness modulus is related to the smaller size, the lower the rate of sand sand rate increases and lower cement content. In the case of sand high rate, as long as a corresponding increase in the amount of cement, pumpable no significant effect on the concrete. 2, coarse aggregate, pumping concrete can be used gravel, crushed stone or gravel and crushed stone aggregate mix. Gravel aggregate concrete pumpability best mixture, followed by the worst gravel aggregate. The minimum diameter of the delivery tube of coarse aggregate maximum diameter (mm) (mm) pebble gravel 1,003,530,803,025,702,020 restrictions on pumping concrete coarse aggregate maximum particle size of the table below the maximum particle size of coarse aggregate transport by pipeline minimum diameter limit. Requirements pebble maximum particle size of not more than 1/3 diameter; no more than 1/4 of gravel caliber. Allowing a small amount of oversized aggregate mixed in, for example, 100mm diameter duct, it can aggregate up to 50mm diameter by a small amount, but this oversized proportion of aggregate must not exceed 1%, and they must be dispersed a. Pumping concrete requirements of coarse aggregate porosity as small as possible, it should be continuous and uniform grading to a smaller amount of cement and sand rates get better pumpability. Coarse aggregate gradation shall meet the requirements in the following table. Coarse aggregate gradation criteria: aggregate by the percentage weight of each standard sieve mesh size range table size within a variety of aggregate nominal size range (mm) (mm) 50 40 30 25 20 15 10 5 2.5 30 -5 100100-9575-40 35-1010-05-0 25-5100100-90 90-6050-2010-0 5-020-5100-90 100-90 (80-55 ) 55-2010-05-0 pumpability of concrete aggregate gradation for intermittent or non-uniform reaction is very sensitive. A component shortage, Manual brick making machinery china price or appear in concrete partial homogenization of the coarse aggregate, are likely to produce a pumping clogging accident. Coarse aggregate proportion of the total aggregate has a great influence on the concrete pumpability, performance pumping concrete pump pressure and volumetric efficiency changes. That is the real use, as long as the good control of the rate of sand, coarse aggregate amount of naturally under control.
Third, pumping concrete mix adjustment
In the construction, in the objective conditions, to the original design of the concrete mix can not be fully realized, to change certain parts of the concrete in the group. A guarantee concrete pumpability, the need for other components to make adjustments, it is common to adjust the rate of water and sand. According to a variety of changing conditions and adjust their own determination method, in order to achieve a suitable pumping appropriate.