MB 值一般不大于 0.5时，吸附性物质很少的机制砂，可起到减水作用，用在混凝土中作用最好，划为Ⅰ类；0.5＜MB≤1.0 时，机制砂中会含有少数的粘土类物质，对混凝土功能的影响并不显着，还能改善混凝土的和易性，划为Ⅱ类；
1.0＜MB≤1.4 时，石粉中会含有不到30% 的粘土类物质，对混凝土的用水量有一定的增大影响，但综合机制砂的其他特点，并不影响机制砂混凝土的质量，可正常使用，划为Ⅲ类，用于低强度等级混凝土时，可解决因胶凝资料用量少带来的和易性差的问题，强度、耐久性等功能也能得到确保。当 MB 大于1.4 或不合格时，石粉中的吸附性物质含量已超过30% ，用于混凝土中会对其作业性带来很大的不利影响，一起影响混凝土的强度和耐久性，故应对石粉含量进行严厉约束。
When the MB value is generally not more than 0.5, the mechanism sand with few adsorptive substances can play a role in reducing water, which is best used in concrete and is classified as Class I. When the MB value is less than 0.5, the mechanism sand will contain a small number of clay substances, which has no significant effect on the concrete function and can also improve the workability of concrete. It is classified as Class II. ;
1.0 < MB < 1.4, the stone powder will contain less than 30% of the clay material, which has a certain impact on the water consumption of concrete, but the other characteristics of the machine-made sand do not affect the quality of the machine-made sand concrete, can be used normally, classified as class III, used in low strength concrete, can be solved because of the amount of cementing data. The problems of poor workability and strength and durability can also be ensured. When MB is more than 1.4 or not up to standard, the content of adsorptive substances in stone powder has exceeded 30%, which will bring great adverse effects on the workability of concrete, and affect the strength and durability of concrete together. Therefore, the content of stone powder should be strictly restricted.
For medium and low strength concrete, the right amount of stone powder (MB value is less than 1.4) is advantageous. The GB/T14684-2011 Code for Construction Sand stipulates that when the MB value is less than 1.4, the stone powder content should be less than 10%. It is also stated that the index can be determined by negotiation between the supplier and the demander after experimental verification. The content of stone powder produced by dry sand process is usually between 9-15%. This filling is beneficial to the consumption of expanded stone powder.