## Dr. SaMeH S. Ahmed

Associate Prof. of Environmental Engineering

# Porosity

Porosity or void fraction is a measure of the void (i.e., "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as apercentage between 0–100%. The term is used in multiple fields including pharmaceuticsceramicsmetallurgymaterialsmanufacturingearth sciences and construction.

## Porosity in earth sciences and construction

Used in geologyhydrogeologysoil science, and building science, the porosity of a porous medium (such as rock or sediment) describes the fraction of void space in the material, where the void may contain, for example, air or water. It is defined by the ratio:

$phi = frac{V_V}{V_T}$

where VV is the volume of void-space (such as fluids) and VT is the total or bulk volume of material, including the solid and void components. Both the mathematical symbols $phi$ and$n$ are used to denote porosity.

Porosity is a fraction between 0 and 1, typically ranging from less than 0.01 for solid granite to more than 0.5 for peat and clay. It may also be represented in percent terms by multiplying the fraction by 100.

The porosity of a rock, or sedimentary layer, is an important consideration when attempting to evaluate the potential volume of water or hydrocarbons it may contain. Sedimentary porosity is a complicated function of many factors, including but not limited to: rate of burial, depth of burial, the nature of the connate fluids, the nature of overlying sediments (which may impede fluid expulsion). One commonly used relationship between porosity and depth is given by the Athy (1930) equation:[2]

$phi(z) = phi_0 e^{-kz},$

where $phi_0$ is the surface porosity, $k$ is the compaction coefficient (m−1) and $z$ is depth (m).

A value for porosity can alternatively be calculated from the bulk density $ho_{ ext{bulk}}$ and particle density $ho_{ ext{particle}}$:

$phi = 1-frac{ ho_{ ext{bulk}}}{ ho_{ ext{particle}}}$

Normal particle density is assumed to be approximately 2.65 g/cm3, although a better estimation can be obtained by examining the lithology of the particles.

### Porosity and hydraulic conductivity

Porosity can be proportional to hydraulic conductivity; for two similar sandy aquifers, the one with a higher porosity will typically have a higher hydraulic conductivity (more open area for the flow of water), but there are many complications to this relationship. The principal complication is that there is not a direct proportionality between porosity and hydraulic conductivity but rather an inferred proportionality. There is a clear proportionality between pore throat radii and hydraulic conductivity. Also, there tends to be a proportionality between pore throat radii and pore volume. If the proportionality between pore throat radii and porosity exists then a proportionality between porosity and hydraulic conductivity may exist. However, as grain size and/or sorting decreases the proportionality between pore throat radii and porosity begins to fail and therefore so does the proportionality between porosity and hydraulic conductivity. For example: clays typically have very low hydraulic conductivity (due to their small pore throat radii) but also have very high porosities (due to the structured nature of clay minerals), which means clays can hold a large volume of water per volume of bulk material, but they do not release water rapidly and therefore have low hydraulic conductivity.

### Office hours

Sunday:     12-1

Monday:     12-1

Tuesday:     10-12

Wednesday: 10-11

You are welcome to contact me by at any time

You  may also contact me via WhatsApp group, ..

Ext. 2524

### Civil Eng. Students

DON'T miss!

As we approaching the second midterm exams..  Get ready and remember our offices are open to answer you . do not hesitate to .contact me if you have difficulties

For CE 370 students : I do apologize for did not attend the extra lab session that proposed to be on Wednesday at 6 am.  Sorry

Good Luck

### Announcements

My Dear Students

.contact me  to sort it out

There will be an orientation session in the midell of this term to help you select your track in Civil and Environmental Engineering

### Event

#### Special Issue

Published Online on January 2016

### Mining Engineering

Mining engineering is an engineering discipline that involves practice, theory, science, technology, and the application of extracting and processing minerals from a naturally occurring environment. Mining engineering also includes processing minerals for additional value.

### Environmental Engineering

Environmental engineers are the technical professionals who identify and design solutions for    environmental problems. Environmental engineers provide safe drinking water, treat and properly dispose of wastes, maintain air quality, control water pollution, and remediate sites contaminated due to spills or improper disposal of hazardous substances. They monitor the quality of the air, water, and land. And, they develop new and improved means to protect the environment.

### Proverb

Actions speak louder than words

### Univeristies

Universities I've worked in

Assuit University (Home University), Egypt

Imperial College, London, UK

King Saud University, KSA

,Majmaah University

### Also visit

https://www.researchgate.net/profile/Sameh_Ahemd

and give me

### Think

How many red balls we need to make balance

### Sports

Egypt vs Tunisia (Handball final)  30/1/2016

### Course 2016/17-1

1. Computer Applications in Surveying  CE 473
2. Surveying 1 CE 370
3. Photogrammetry CE 474
4. Surveying II  CE 371
5. Design I  (round 4) CE 498

Rule #7

### Latest

Member of the Editorial Board: " Journal of Water Resources and Ocean Sciences"  2013

Participating in The Third International Conference on Water, Energy and Environment,(ICWEE) 2015 - American University of Sharjah, UAE 24-26 March 2015 with a Paper and Poster

New article

Recovery of Titania from Waste-Sludge of Majmaah Water Treatment Plant

"Production of Titania Nano-particles from Wast-

Sludge

### Coming soon

Results of M2 CE311

### Student Conference

Participation  in the 6Th Student Conference

With a paper and oral presentation

From the Senior Design Project CE499 -35

See inside, the paper, and presentation

## Surveying  I -  CE 370 - 2016-2017-1

 Power point Sheets Lecture notes Second Midterm Exam Results Model Answer

Student Performance Records

## Surveying II - CE 371 - 2016-2017-1

 Lectures First midterm exam Lab Results

See Inside

Student Performance Records

## CE 473

 Lecturers Power point Sheets Exams + Quizzes Results

### 2015-2016-2 - Photogrammetry  CE474

 Available 0-1-2-3-4 Power point Available Quizzes 2 and 3 with model Answer Quizzes Available Chapter 1,2,3,4,5 Lecture notes Report 1  Cameras Report Y 60 marks Exams

See Inside

Student Performance Records

## Environmental Engineering 1

CE 360: Environmental Engineering 1

37-2

 Y PP0-1-2-3,4 Power point Y 1,2,3,4,5 Chapters Water quality Poster + Climate Change Reports will be announced (Quiz #2 will be using D2L- Online Quizzes Y Quizzez 2,3 and 4 with model answer and results Exams and results

### Engineering Report Writing

GE 306: Engineering Report Writing

### Senior Design 2 - CE 499

Meeting on 14-4-2015

Second Best paper from Senior Design Projects in 2015

Paper title:

### Evaluation of Groundwater Quality Parameters using Multivariate Statistics- a case Study of Majmaah, KSA

Students:

Abdullah A. Alzeer

Husam K. Almubark

Maijd M. Almotairi

### CE 360-Summer Course

Environmental Engineering I

## Welcome to CE360 second Term 2015-2016

### Engineering Practice

Engineering Practice GE 307

### الهيئة الوطنية للاعتماد والتقويم الاكاديمي

See what can you get from Google!! more than translation and locations

### Contact me

Mobile: 00966598311652

s.mohamed@mu.edu.sa

### Thank you

Your frequent visit to my website has helped  a lot to get the 2nd place in the university competition in the  year 1434-2013... Thanks very mush and please keep following my work

زيارتكم المتكررة لموقعي ساهمت في حصولي على المركز الثاني لاحسن المواقع الشخصية بجامعة المجمعة ...لكم جميعا خالص شكري وتقديري

## CE 212

 Y from PP0 to PP 6 + PDF Power points Y Midterm #2 + Model Answer + results Exams Y lab 3 Labs Solution of Quiz 4 + Results HW

## CE 311

M2+ model Answer + PP 1-9 = PDF 1-9 all are available

Sheets 2 + 4 with model Answers

Results of M2

### إحصائية الموقع

عدد الصفحات: 1412

البحوث والمحاضرات: 1541

الزيارات: 51017