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

Considere uma amostra de agregados miúdos sendo peneirados através de um conjunto padrão de peneiras. Observar o peso dos agregados retidos em cada peneira.
Calcular o peso acumulado dos agregados retidos em cada peneira e expressá-lo em percentagem do peso total da amostra.
Se, por exemplo, todas as partículas forem retidas sobre ou acima de uma determinada peneira e nada passar por ela, a porcentagem cumulativa retida para essa peneira e aquelas empilhadas embaixo dela é inserida como 100.
O módulo de finura é calculado somando a percentagem acumulada retida em cada peneira e dividindo o total por 100.
O módulo de finura é um índice numérico que representa a classificação de agregados.
Quando são utilizados agregados da mesma fonte, pequenas variações na gradação dos agregados miúdos são menos óbvias visualmente do que com os agregados graúdos.
Essas diferenças serão refletidas no valor do módulo de finura, que será mais perspicaz para agregados finos do que para agregados graúdos.
Normalmente, o valor do módulo de finura para agregados miúdos varia de 2,3 a 3,1; quanto maior o valor, mais grossos são os agregados.

módulo de finura

O módulo de finura (FM) do agregado é um índice numérico que mede a grossura ou finura das partículas. Ele é calculado adicionando as porcentagens cumulativas de agregado retido em cada uma de uma série especificada de peneiras e dividindo a soma por 100.

Considere realizar análise de peneira em areia por meio de um conjunto de peneiras ASTM. O peso do agregado retido em cada peneira e bandeja colocada no fundo é registrado, conforme fornecido na Coluna B da Tabela 1.

Para determinar o módulo de finura da areia, calcule o peso cumulativo do agregado retido em cada peneira (Coluna C da Tabela 1) e expresse-o como uma porcentagem do peso total (Coluna D da Tabela 1). Finalmente, a soma das porcentagens cumulativas de agregado retido em cada peneira é determinada e multiplicada por 100 para obter o módulo de finura da areia.

Tabela 1: Análise de peneira em areia

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Coluna A</td>
			<td>Coluna B</td>
			<td>Coluna C</td>
			<td>Coluna D</td>
		</tr>
		<tr>
			<td>Peneira ASTM</td>
			<td>Peso retido
 em cada peneira (g)
 </td>
			<td>Peso acumulado
 retido em cada peneira (g)
 </td>
			<td>Porcentagem acumulada retida em cada peneira (%)</td>
		</tr>
		<tr>
			<td>
			⅜ cm
			</td>
			<td>0</td>
			<td>0</td>
			<td>0</td>
		</tr>
		<tr>
			<td>No. 4</td>
			<td>5</td>
			<td>0+5 = 5</td>
			<td>5/500 = 1</td>
		</tr>
		<tr>
			<td>No. 8</td>
			<td>55</td>
			<td>5+55 = 60</td>
			<td>60/500 = 12</td>
		</tr>
		<tr>
			<td>No. 16</td>
			<td>65</td>
			<td>60+65 = 125</td>
			<td>125/500 = 25</td>
		</tr>
		<tr>
			<td>No. 30</td>
			<td>90</td>
			<td>125+90 = 215</td>
			<td>215/500 = 43</td>
		</tr>
		<tr>
			<td>No. 50</td>
			<td>160</td>
			<td>215+160 = 375</td>
			<td>375/500 = 75</td>
		</tr>
		<tr>
			<td>No. 100</td>
			<td>90</td>
			<td>375+90 = 465</td>
			<td>465/500 = 93</td>
		</tr>
		<tr>
			<td>Panela de baixo</td>
			<td>35</td>
			<td>Peso total = 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;">
Em geral, a areia tem um módulo de finura de cerca de 2,3 a 3,1. Valores mais baixos indicam areia mais fina, enquanto valores mais altos significam que a areia é mais grossa.

Módulo de Finura

Considere uma amostra de agregados miúdos sendo peneirados através de um conjunto padrão de peneiras. Observar o peso dos agregados retidos em cada peneira.
Calcule o ...

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Civil Engineering

Engenharia Civil

Unit 1

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Aggregates and Water

Agregados e Água

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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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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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