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

標準的なふるいのセットを通してふるいにかけられる細かい骨材のサンプルを考えてみましょう。各ふるいに保持されている骨材の重量に注意してください。
各ふるいに保持されている骨材の累積重量を計算し、それを総サンプル重量のパーセンテージとして表します。
例えば、すべての粒子が特定のふるいの上または上に保持され、何も通過しない場合、そのふるいとその下に積み重ねられた粒子の累積保持率は100として入力されます。
細かさ弾性率は、各ふるいに保持されている累積パーセンテージを合計し、その合計を100で割ることによって計算されます。
細かさ係数は、骨材の等級付けを表す数値指標です。
同じソースからの骨材を使用する場合、細かい骨材のグラデーションのわずかな変化は、粗い骨材の場合よりも視覚的に目立ちにくくなります。
これらの違いは、細粒度係数の値に反映され、粗い骨材よりも細かい骨材の方が洞察に富んでいます。
通常、細骨材の細かさ係数の値は 2.3 から 3.1 の範囲であり、値が大きいほど、凝集体は粗くなります。

細かさ係数

骨材の細かさ係数 (FM) は、粒子の粗さまたは細かさを測定する数値指標です。これは、指定された一連のふるいのそれぞれに保持された骨材の累積パーセンテージを加算し、その合計を 100 で割ることによって計算されます。
ASTM ふるいセットを通して砂のふるい分析を行うことを検討してください。各ふるいと底に置かれた器に保持された骨材の重量は、表 1 の列 B に示すように記録されます。
砂の細かさ係数を求めるには、各ふるいに残った骨材の累積重量（表 1 の列 C）を計算し、総重量（表 1 の列 D）のパーセンテージとして表します。最後に、各ふるいに残った骨材の累積パーセンテージの合計を求め、100 を掛けて砂の細かさ係数を求めます。
表1: 砂のふるい分析

<table style="margin: 0 auto;">
	<tbody style="border: 1px solid black;">
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">列A</td>
			<td style="color: black; border: 1px solid black; text-align: center;">列B</td>
			<td style="color: black; border: 1px solid black; text-align: center;">列C</td>
			<td style="color: black; border: 1px solid black; text-align: center;">列D</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">ASTMふるい</td>
			<td style="color: black; border: 1px solid black; text-align: center;">各ふるいに残った重量 (g)</td>
			<td style="color: black; border: 1px solid black; text-align: center;">各ふるいに残った累積重量 (g)</td>
			<td style="color: black; border: 1px solid black; text-align: center;">各ふるいに残った累積割合（％）</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">⅜センチ</td>
			<td style="color: black; border: 1px solid black; text-align: center;">0</td>
			<td style="color: black; border: 1px solid black; text-align: center;">0</td>
			<td style="color: black; border: 1px solid black; text-align: center;">0</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">第4位</td>
			<td style="color: black; border: 1px solid black; text-align: center;">5</td>
			<td style="color: black; border: 1px solid black; text-align: center;">0+5 = 5</td>
			<td style="color: black; border: 1px solid black; text-align: center;">5/500 = 1</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">8位</td>
			<td style="color: black; border: 1px solid black; text-align: center;">55</td>
			<td style="color: black; border: 1px solid black; text-align: center;">5+55 = 60</td>
			<td style="color: black; border: 1px solid black; text-align: center;">60/500 = 12</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">第16号</td>
			<td style="color: black; border: 1px solid black; text-align: center;">65</td>
			<td style="color: black; border: 1px solid black; text-align: center;">60+65 = 125</td>
			<td style="color: black; border: 1px solid black; text-align: center;">125/500 = 25</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">30番</td>
			<td style="color: black; border: 1px solid black; text-align: center;">90</td>
			<td style="color: black; border: 1px solid black; text-align: center;">125+90 = 215</td>
			<td style="color: black; border: 1px solid black; text-align: center;">215/500 = 43</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">第50号</td>
			<td style="color: black; border: 1px solid black; text-align: center;">160</td>
			<td style="color: black; border: 1px solid black; text-align: center;">215+160 = 375</td>
			<td style="color: black; border: 1px solid black; text-align: center;">375/500 = 75</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">第100号</td>
			<td style="color: black; border: 1px solid black; text-align: center;">90</td>
			<td style="color: black; border: 1px solid black; text-align: center;">375+90 = 465</td>
			<td style="color: black; border: 1px solid black; text-align: center;">465/500 = 93</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">下皿</td>
			<td style="color: black; border: 1px solid black; text-align: center;">35</td>
			<td style="color: black; border: 1px solid black; text-align: center;">総重量 = 465+35 = 500</td>
			<td style="color: black; border: 1px solid black; text-align: center;"></td>
		</tr>
	</tbody>
</table>

<img alt="Equation1" src="/files/ftp_upload/16872/16872%20_Equation_PT_001v2.svg" style="height: 14px;">
<img alt="Equation2" src="/files/ftp_upload/16872/16872%20_Equation_PT_002v2.svg" style="height: 36px;">

一般的に、砂の細かさ係数は 2.3 ～ 3.1 程度です。値が低いほど砂が細かくなり、値が高いほど砂が粗くなります。

標準的なふるいのセットを通してふるいにかけられる細かい骨材のサンプルを考えてみましょう。各ふるいに保持されている骨材の重量に注意してください。
計算します...

Education

JoVE Core

Civil Engineering

土木工学

Unit 1

ユニット1

Aggregates and Water

骨材および水

KEY TERMS AND CONCEPTS

主要用語と概念

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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key terms and concepts

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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civil engineering

Fineness Modulus from Sieve Analysis

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