I. Introduction

¡¡¡¡Concrete hollow block and pavers are generally fully automatic or semi-automatic block making machine production . Immediately after the ejection molding machine , it must be dry concrete . Then , using what kind of dry concrete mix in order to make products to meet the design strength and to meet production requirements? Some units currently calculated according to Paul Mix Romy , there is a certain error, because it is the experience of the plastic concrete statistical formula is not suitable for dry concrete mixture ratio calculation ; some units with reference to other units than done , not necessarily Is correct , the best ; also try to test the unit to use their experience , it is difficult to find a reasonable proportion, to waste a lot of manpower and material resources . Strength enough, throwing cement, sand the surface not only on increasing the rate , using pebbles and so on, these practices are unscientific . To this end, we discussed the hard dry concrete mix and strength of factors , made of concrete pavement with load-bearing concrete hollow block and brick and block filled with more than selection.

2 , Mix Design of calculation steps

Mix Concrete Block generally calculate three steps .

1 , to determine and calculate the basic parameters

¡¡¡¡First, determine the products according to user the strength grade , and then empty heart rate determined under the block of concrete of strength . In general, the block 's strength should be about one-third strength of concrete , while the design concrete strength should be increased to 110 % to 115% . Next, the product structure and molding ability to choose water-cement ratio and cement content , water cement ratio than a road block with brick smaller . And products based on economic strength and then asked to select the amount of cement, and then poke under dry concrete and gravel porosity and the coefficient of material bulk density measured in the gravel , sand ratio calculation .

¡¡¡¡2 , calculation of the initial mix

According to water-cement ratio and cement content , calculated per cubic meter of water . Calculated water absorption according to stone , sand fineness, cement varieties regulation . When the stone is greater than 1.5% water absorption , the water consumption to increase , according to the amount of coarse aggregate and water absorption , calculated to increase the amount of water ; dust content and more water should be increased ; with fine sand , the per cubic meter Concrete increased 10 kg of water ; Finally, the absolute volume method and the sand is given by the equation , simultaneous equations to calculate the amount gravel , draw all kinds of raw materials per cubic meter of concrete usage .

3 , test mix and adjusted

Try and mix 12 liters of concrete , dry hard to do experiments to see whether the design of dried concrete hardness requirements . Too dry hardness concrete , you need to maintain constant water-cement ratio , increasing the amount of cement and water ; if dry hardness concrete is too small, need to increase the amount of gravel , sand to keep the rate unchanged; if it considers excessive or sand Insufficient, can change the sand , increase the amount of sand or gravel to adjust . Then find the best water-cement ratio , cement ratio is usually calculated with the upper and lower adjacent , and a difference of ¡À 0.05 water-cement ratio and calculation of the three water-cement ratio to do three sets of tests , remove from strength to meet the requirements , and the amount of cement has A group of water-cement ratio less production of water-cement ratio as . Finally find the test mix -adjusted dosage of the various materials to determine the bulk density of concrete mixed with the whole thing to calculate a variety of materials per cubic meter of concrete usage .

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