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

考虑通过一组标准筛子筛分细骨料样品。注意每个筛子上保留的骨料重量。
计算每个筛子上保留的聚集体的累积重量，并将其表示为总样品重量的百分比。
例如，如果所有颗粒都保留在特定筛子上或上方，并且没有任何东西通过它，则该筛子及其下方堆叠的颗粒保留的累积百分比将输入 100。
细度模量的计算方法是将每个筛子上保留的累积百分比相加，然后将总数除以 100。
成色模量是代表骨料分级的数字指数。
当使用来自同一来源的骨料时，细骨料的级配的微小变化在视觉上不如粗骨料明显。
这些差异将反映在细度模量值中，细粒模量值比粗粒更能理解细粒。
通常，细骨料的细度模量值在 2.3 到 3.1 之间;该值越高，骨料越粗。

细度模数

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。

考虑通过一组标准筛子筛分细骨料样品。注意每个筛子上保留的骨料重量。
计算 ...

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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

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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Fineness Modulus from Sieve Analysis

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