Name: fineness modulus from sieve analysis
Uploaded: 2024-11-07T14:48:25.000Z
Duration: 1 min 19 s
Channel: JoVE

将细集料样品通过一组标准筛进行筛分，记录各筛上残留的集料重量。
计算各筛上截留的集料累计质量，并将其表示为总样品质量的百分比。
例如，如果所有颗粒均被某一特定筛子截留或停留在其上方，且没有任何颗粒通过该筛子，则该筛子及其下方所有叠放筛子的累计截留百分比记为100。
细度模数通过将各筛上累计筛余的百分比相加，再将总和除以100来计算。
细度模数是一个表示集料级配的数值指标。
当使用同一来源的集料时，细集料级配的微小差异相比粗集料而言较不明显。
这些差异将反映在细度模数上，对于细集料而言，细度模数提供的信息比粗集料更具参考价值。
通常，细集料的细度模数范围为2.3至3.1；数值越高，集料越粗。

细度模数

Fineness Modulus

骨料的细度模数 (FM) 是衡量颗粒粗细程度的数值指标。计算方法是将特定系列筛子上保留的骨料的累计百分比相加，然后将总和除以 100。

考虑通过一组 ASTM 筛子对沙子进行筛分分析。记录每个筛子和放在底部的盘中保留的骨料重量，如表 1 的 B 列所示。

为确定砂的细度模数，计算每个筛子上骨料的累计重量（表1的C列），并将其表示为总重量的百分比（表1的D列）。最后，确定每个筛子上骨料的累计百分比之和，并乘以100，即可得到砂的细度模数。 

表 1:砂子的筛分分析

<table style="text-align: center;" border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>A 列</td>
			<td>B 列</td>
			<td>C 列</td>
			<td>D 列</td>
		</tr>
		<tr>
			<td>ASTM 筛</td>
			<td>每个筛子上保留的重量（g）</td>
			<td>每个筛子上残留的累计重量（g）</td>
			<td>每个筛子上累计保留百分比（％）</td>
		</tr>
		<tr>
			<td>
			⅜ 厘米
			</td>
			<td>0</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>4号筛</td>
			<td>5</td>
			<td>0+5 = 5</td>
			<td>5/500 = 1</td>
		</tr>
		<tr>
			<td>8号筛</td>
			<td>55</td>
			<td>5+55 = 60</td>
			<td>60/500 = 12</td>
		</tr>
		<tr>
			<td>16号筛</td>
			<td>65</td>
			<td>60+65 = 125</td>
			<td>125/500 = 25</td>
		</tr>
		<tr>
			<td>30号筛</td>
			<td>90</td>
			<td>125+90 = 215</td>
			<td>215/500 = 43</td>
		</tr>
		<tr>
			<td>50号筛</td>
			<td>160</td>
			<td>215+160 = 375</td>
			<td>375/500 = 75</td>
		</tr>
		<tr>
			<td>100号筛</td>
			<td>90</td>
			<td>375+90 = 465</td>
			<td>465/500 = 93</td>
		</tr>
		<tr>
			<td>底盘</td>
			<td>35</td>
			<td>总重量 = 465+35 = 500</td>
			<td></td>
		</tr>
	</tbody>
</table>
<img alt="Eq1" src="/files/ftp_upload/16872/16872%20_Equation_PT_001v2.svg" style="height: 14px;">
<img alt="Eq2" src="/files/ftp_upload/16872/16872%20_Equation_PT_002v2.svg" style="height: 36px;">
一般情况下，沙子的细度模数在2.3至3.1之间，模数越低，沙子越细;模数越高，沙子越粗。

考虑将细集料样品通过一组标准筛进行筛分。记录每只筛上截留的集料重量。  
计算……

Education

教育

JoVE Core

Civil Engineering

土木工程

Unit 1

第一单元

Aggregates and Water

骨料与水

KEY TERMS AND CONCEPTS

关键术语与概念

fineness modulus from sieve analysis

Fineness modulus is a numerical index used to describe how coarse or fine aggregate particles are. For sand, it is found from sieve analysis using a standard set of ASTM sieves. The result helps show whether the sample is finer or more coarse.

To calculate fineness modulus, first record the weight of aggregate retained on each sieve and in the pan at the bottom. Then find the cumulative weight retained on each sieve. Next, express each cumulative weight as a percentage of the total sample weight. The fineness modulus is obtained by adding those cumulative percentages and dividing the sum by 100.

A sand sample can be tested with sieves such as ⅜ inch, No. 4, No. 8, No. 16, No. 30, No. 50, and No. 100. In the example, the retained weights are 0 g, 5 g, 55 g, 65 g, 90 g, 160 g, 90 g, and 35 g in the bottom pan. The cumulative percentages retained are 0, 1, 12, 25, 43, 75, and 93, based on a total weight of 500 g.

In general, sand has a fineness modulus of about 2.3 to 3.1. Lower values mean the sand is finer. Higher values mean the sand is more coarse.

Fineness Modulus from Sieve Analysis

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Learn how fineness modulus is calculated from sieve analysis of sand, using cumulative retained percentages on ASTM sieves to judge particle size.

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Fineness Modulus from Sieve Analysis

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