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Which can affect concrete mixer machine efficiency?

24May

Composition as an Indicator of Efficiency is one factors affecting concrete mixer machine efficiency. This article analysis that how to affect concrete mixer machine efficiency?

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Sample tests of Composition as an Indicator of Efficiency for concrete mixer machine
A more direct method to determine the efficiency of a mixer would be to measure the homogeneity of the concrete. This method does not rely on an assumption about the dependency of macroscopic properties on the concrete composition. The measure of the concrete homogeneity can be achieved by determining the distribution of the various solid constituents such as coarse and fine aggregates, mineral admixtures, and cement paste throughout the mixture. However, there are no standard tests to determine homogeneity. Nevertheless, the analysis of samples of concrete taken in various parts of a mixer or at various times during the discharge is usually accomplished by washing out the cement paste and then by sieving the aggregates. By weighing the sample before and after washing out the cement paste, the cement paste content can be estimated. The aggregates collected after the cleaning period are then dried and sieved and their size distribution is analyzed. Because the cement paste is washed out and determined as a whole, there is no provision to determine the dispersion of the mineral admixtures or very fine fillers. As demands for higher performance concretes grow, more precise methods will be needed, such as microscopic observations by scanning electron microscope (SEM), to measure the distribution of the mineral admixtures.

According to test process, we can abstract the results and ask some questions
Based on the concept that measuring compositional homogeneity of a mixture can provide evidence of the efficiency of the mixer, RILEM tried to establish a classification of mixer efficiency by defining three classes of mixers: ordinary mixer, performance mixer, and high performance mixer. Each class is defined by the range of four criteria: water/fine ratio, fine content (mainly the cement and other fine powder), coarse aggregate content (between D/2 and D, with D the maximum aggregate size) and air content. Several samples (the number is not specified) are taken from the mixer or from the concrete discharge, and the above parameters are measured. The average of all the measurements collected for each parameter and the standard deviation are calculated. The coefficient of variation (ratio of standard deviation to the average, COV) gives a measure of the homogeneity of the concrete produced, i.e., a smaller COV implies a more uniform mixture. We abstract the results according to the criteria and the values of COV requested. The COV does not depend on the type of concrete selected because it only depends on the relative variation of the parameters for a concrete. This method, proposed by RILEM, is the only attempt by any organization to standardize the process of measuring the efficiency of a concrete mixer.
 


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