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

Si consideri un campione di aggregati fini che viene setacciato attraverso una serie standard di setacci. Notare il peso degli aggregati trattenuti su ciascun setaccio.
Calcolare il peso cumulativo degli aggregati trattenuti su ciascun setaccio ed esprimerlo in percentuale del peso totale del campione.
Se, per esempio, tutte le particelle sono trattenute sopra o sopra un particolare setaccio, e nulla passa attraverso di esso, la percentuale cumulativa trattenuta per quel setaccio e per quelle impilate sotto di esso è inserita come 100.
Il modulo di finezza si calcola sommando la percentuale cumulativa trattenuta su ciascun setaccio e dividendo il totale per 100.
Il modulo di finezza è un indice numerico che rappresenta la classificazione degli aggregati.
Quando si utilizzano aggregati provenienti dalla stessa fonte, lievi variazioni nella gradazione degli aggregati fini sono meno evidenti dal punto di vista visivo rispetto agli aggregati grossolani.
Queste differenze si rifletteranno nel valore del modulo di finezza, che sarà più utile per gli aggregati fini rispetto agli aggregati grossolani.
Tipicamente, il valore del modulo di finezza per gli aggregati fini varia da 2,3 a 3,1; più alto è il valore, più grossolani sono gli aggregati.

modulo di finezza

Il modulo di finezza (MF) dell'aggregato è un indice numerico che misura la grossolanità o la finezza delle particelle. Si calcola sommando le percentuali cumulative di aggregato trattenuto su ciascuna di una serie specifica di setacci e dividendo la somma per 100.
Si consideri di eseguire un'analisi del setaccio sulla sabbia attraverso un setaccio UNI EN standard. Il peso dell'aggregato trattenuto in ogni setaccio e in ogni bacinella posizionati sul fondo viene registrato, come indicato nella colonna B della tabella 1.
Per determinare il modulo di finezza della sabbia, calcolare il peso cumulativo di aggregato trattenuto su ciascun setaccio (colonna C della tabella 1) ed esprimerlo come percentuale del peso totale (colonna D della tabella 1). Infine, la somma delle percentuali cumulative di aggregato trattenuto su ciascun setaccio viene determinata e moltiplicata per 100 per ottenere il modulo di finezza della sabbia.
Tabella 1: Analisi del setaccio sulla sabbia

<table style="margin: 0 auto;">
 <tbody style="border: 1px solid black;">
 <tr>
 <td style="color: black; border: 1px solid black; text-align: center;">Colonna A</td>
 <td style="color: black; border: 1px solid black; text-align: center;">Colonna B</td>
 <td style="color: black; border: 1px solid black; text-align: center;">Colonna C</td>
 <td style="color: black; border: 1px solid black; text-align: center;">Colonna D</td>
 </tr>
 <tr>
 <td style="color: black; border: 1px solid black; text-align: center;">Setaccio UNI EN</td>
 <td style="color: black; border: 1px solid black; text-align: center;">Peso trattenuto su ogni setaccio (g)</td>
 <td style="color: black; border: 1px solid black; text-align: center;">Peso cumulativo trattenuto su ogni setaccio (g)</td>
 <td style="color: black; border: 1px solid black; text-align: center;">Percentuale cumulativa trattenuta su ogni setaccio (%)</td>
 </tr>
 <tr>
 <td style="color: black; border: 1px solid black; text-align: center;">9,5 mm</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;">UNI EN(4,74 mm)</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;">UNI EN(2,36 mm)</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;">UNI EN(1,18 mm)</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;">UNI EN(0,6 mm)</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;">UNI EN(0,3 mm)</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;">UNI EN(0,15 mm)</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;">Fondo della padella</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;">Peso totale = 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;">

In generale, la sabbia ha un modulo di finezza compreso tra 2,3 e 3,1. Valori più bassi indicano una sabbia più fine, mentre valori più alti indicano una sabbia più grossolana.

Modulo di finezza

Si consideri un campione di aggregati fini che viene setacciato attraverso una serie standard di setacci. Notare il peso degli aggregati trattenuti su ciascun setaccio.
Calcola il ...

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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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