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

חשבו על מדגם של אגרגטים עדינים המנופים באמצעות מערכת סטנדרטית של מסננות. שימו לב למשקל האגרגטים השמורים על כל מסננת.
חשב את המשקל המצטבר של אגרגטים השמורים על כל מסננת ובטא אותו כאחוז ממשקל המדגם הכולל.
אם, למשל, כל החלקיקים נשמרים על מסננת מסוימת או מעליה, ושום דבר לא עובר דרכה, האחוז המצטבר שנשמר עבור אותה מסננת ואלה המוערמים מתחתיה מוזן כ-100.
מודולוס העדינות מחושב על ידי סיכום האחוז המצטבר שנשמר על כל מסננת וחלוקת הסכום הכולל ב- 100.
מודולוס העדינות הוא אינדקס מספרי המייצג את דירוג האגרגטים.
כאשר משתמשים בצברים מאותו מקור, שינויים קלים בהדרגתיות של אגרגטים עדינים פחות ברורים חזותית מאשר עם אגרגטים גסים.
הבדלים אלה יבואו לידי ביטוי בערך מודולוס העדינות, אשר יהיה תובנה רבה יותר עבור אגרגטים עדינים מאשר אגרגטים גסים.
בדרך כלל, הערך של מודולוס העדינות עבור אגרגטים עדינים נע בין 2.3 ל -3.1; ככל שהערך גבוה יותר, כך האגרגטים גסים יותר.

מודול הדקוּת (fineness modulus)

מודול הדקוּת (FM) של אגרגטים הוא מדד מספרי המודד את דרגת הגסות או העדינות של החלקיקים. הוא מחושב על ידי חיבור האחוזים המצטברים של האגרגט שנותר בכל אחת מסדרה מוגדרת של נפות וחלוקת הסכום ב-100.

נבחן ביצוע ניתוח ניפוי של חול באמצעות סדרת נפות ASTM. משקל האגרגט שנשאר בכל נפה ובתחתית המגש נרשם, כפי שמופיע בעמודה B בטבלה 1.

כדי לקבוע את מודול הדקות של החול, מחשבים את המשקל המצטבר של האגרגט שנשאר בכל נפה (עמודה C בטבלה 1) ומביעים אותו באחוזים ממשקל הדגימה הכולל (עמודה D בטבלה 1). לבסוף, מחברים את אחוזי הצבירה של האגרגט שנשאר בכל נפה ומחלקים את הסכום ב-100 כדי לקבל את מודולו הדקות של החול.

טבלה 1: ניתוח מסננת על חול

<div align="center">
<table border="1" dir="rtl">
	<thead>
		<tr>
			<th style="text-align:center">טור A</th>
			<th style="text-align:center">טור B</th>
			<th style="text-align:center">טור C</th>
			<th style="text-align:center">טור D</th>
		</tr>
		<tr>
			<th style="text-align:center">מסננת ASTM</th>
			<th style="text-align:center">המשקל הנשמר על כל מסננת (g)</th>
			<th style="text-align:center">המשקל מצטבר הנשמר על כל מסננת (g)</th>
			<th style="text-align:center">אחוז מצטבר שנשמר על כל מסננת (%)</th>
		</tr>
	</thead>
	<tbody>
		<tr>
			<td style="text-align:center">⅜ ס"מ</td>
			<td style="text-align:center">0</td>
			<td style="text-align:center">0</td>
			<td style="text-align:center">0</td>
		</tr>
		<tr>
			<td style="text-align:center">מספר 4</td>
			<td style="text-align:center">5</td>
			<td style="direction: ltr;text-align:center">0+5 = 5</td>
			<td style="direction: ltr;text-align:center">5/500 = 1</td>
		</tr>
		<tr>
			<td style="text-align:center">מספר 8</td>
			<td style="text-align:center">55</td>
			<td style="direction: ltr;text-align:center">5+55 = 60</td>
			<td style="direction: ltr;text-align:center">60/500 = 12</td>
		</tr>
		<tr>
			<td style="text-align:center">מספר 16</td>
			<td style="text-align:center">65</td>
			<td style="direction: ltr;text-align:center">60+65 = 125</td>
			<td style="direction: ltr;text-align:center">125/500 = 25</td>
		</tr>
		<tr>
			<td style="text-align:center">מספר 30</td>
			<td style="text-align:center">90</td>
			<td style="direction: ltr;text-align:center">125+90 = 215</td>
			<td style="direction: ltr;text-align:center">215/500 = 43</td>
		</tr>
		<tr>
			<td style="text-align:center">מספר 50</td>
			<td style="text-align:center">160</td>
			<td style="direction: ltr;text-align:center">215+160 = 375</td>
			<td style="direction: ltr;text-align:center">375/500 = 75</td>
		</tr>
		<tr>
			<td style="text-align:center">מספר 100</td>
			<td style="text-align:center">90</td>
			<td style="direction: ltr;text-align:center">375+90 = 465</td>
			<td style="direction: ltr;text-align:center">465/500 = 93</td>
		</tr>
		<tr>
			<td style="direction: ltr;text-align:center">תבנית תחתונה</td>
			<td style="text-align:center">35</td>
			<td style="direction: ltr;text-align:center">משקל כולל = 465+35 = 500</td>
			<td style="text-align:center"></td>
		</tr>
	</tbody>
</table>
</div>

<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;">

לסיכום, לחול יש מודול דקות שנע בין 2.3 ל-3.1. ערכים נמוכים מצביעים על חול עדין יותר, בעוד שערכים גבוהים מעידים על חול גס יותר.

מודול הדקוּת (Fineness Modulus)

חשבו על מדגם של אגרגטים עדינים המנופים באמצעות מערכת סטנדרטית של מסננות. שימו לב למשקל האגרגטים השמורים על כל מסננת.
חשב את ...

Education

JoVE Core

Civil Engineering

הנדסה אזרחית

Unit 1

יחידה 1

Aggregates and Water

אגרגטים ומים

KEY TERMS AND CONCEPTS

מונחי מפתח ומושגים

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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civil engineering

Fineness Modulus from Sieve Analysis

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