case study on block foundation productivity

7/31/2019 Case Study on Block Foundation Productivity

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CHAPTER 0NE

INTRODUCTION

A foundation (also called a ground sill) is a structure that transfer loads to

the earth. The footing plays a specific load- bearing roles in as much as they

support the weight of the building. Whether the building rest on post or walls

which in turn rest on the footing. In planning footings be sure to consider the

types of soil in which they will be poured (clay, marshy etc.) At the very

least, footing must be poured below the frost line.

Foundations are generally broken into two categories; shallow foundationand deep foundation.

Shallow foundation is, usually, embedded a meter or so into soil. One

common type is the spread footing which consist of strip or pad of concrete

(or other material) which extends below the frost line and transfer the weight

from wall and columns to the soil or bedrock. Another common type is the

slab-on-grade foundation where the weight of the building is transferred to

the soil through a concrete slab place at the surface.

Deep foundation is used to transfer a load from a structure through an upper

weak layer of soil to a stronger deeper layer of soil. There are different types

of deep foundations including helical piles, impacts, caissons, pier, and earth

stabilized columns. The naming conventions for different types of

foundations vary between different engineers. Historically, piles were wood,

later steel, reinforced concrete, and pre-tensioned concrete.


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PURPOSE OF STUDY

AIM

The primary aim of this study is to produce the working activities,time and cost of the foundation of a given house plan.

OBJECTIVES

To identify the approach to foundation production.To determine suitable time it takes to excavate foundation trenches

To determine the cost it take to excavate the foundation trench

STATEMENT OF PROBLEMSThis case-study is design to know appropriate / correct procedure to

follow in the undertaking of any substructure

SIGNIFICANCE OF STUDY

This study will help the reader to understand a way to forecastfoundation production activities, that is involved in any given house

plan. Also the considerations to put in place as to the difficulties that

may be encountered.


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METHODOLOGY

The following procedure among other things has been the method that

will be employed to carry out this study:

Site clearance and setting out of the house plane Excavation of the trench and pouring of concrete footings Laying of foundation block wall and backfilling. Setting the formwork, filling hardcore and over site concrete

SCOPE AND LIMITATION

The study focuses only on the assessment of foundation activities of

the two bedroom bungalow plan. It determines the time and cost

involved in the sub-structure.


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CHAPTER TWO

LITERATUE REVIEWFoundation is the most essential part of structure of any

building. The concrete footing most rest on firm soil

and extend below frost line. Build footing on lightly

moist soil (be sure that soil is not wet). National and

local building codes indicate footing depth; ask your

local building department.

Flat surface footing is used when the foundation wall is madeof concrete block or cast concrete. It is possible to make a

grove in the footing to hold the foundation concrete. Just

insert the edge of a 2x4 on top of the footing and remove as

the concrete has hardened.

Pier foundation(12diam) is used as foundation or footing orfooting without any other support. They are evenly spread

around the building perimeter according to the local building

codes. Dig a hole to install the sonotube and fill with

concrete.

Excavation and formworkExcavation; place stakes to indicate footing area. Removing

line from batter boards. Keep the area free from debris and

dirt.

Formwork; headed nail are easier to remove than ordinary

nails. Nail them into the stakes down to the formwork. Oil

formwork surface touching concrete with waste crank-case

oil.


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Foundation tiesmetal or plastic wires that hold thefoundation panels and rebar in place while concrete is being

poured.

Gradeground level or elevation at any given point.Excavation or buildings foundation. Correct grading cause

water to drain away from the buildings foundation.

Causes of foundation failureMany houses are constructed with foundations that are

inadequate for the soil condition existing on the site. Because

of the lack of suitable land, houses are often built on marginalland that has insufficient bearing capacity to support the

substantial weight of a structure. In addition, there are many

areas of the country where the near surface soils consist

predominantly of expansive clay that shrink and swell as their

moisture content changes. If the bearing soil consist of

expansive clay, foundation movement can occur uniformly

across the entire slab. Any of the following can cause

moisture in the soil to fluctuate vegetation (roots), poor

drainage, plumbing leaks, evaporation, and wet/dry rain

cycles.

Slab-on-grade foundation depends upon the upper-most soil

layers to provide sufficient bearing capacity to support the

structure and keep the foundation stable. If the bearing soil

was insufficiently compacted prior to construction, thefoundation is subject to settlement as the supporting soil

consolidates.

Symptoms of foundation failureThe sign of foundation failure do not become obvious until

after there are serious problems with the foundation. The most

obvious sign will be door that do not close properly anymore,


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windows that stick and diagnosis crack in the interior and

exterior wall. Less obvious symptoms are small cracks in the

foundation or floor and uneven floors. Sixty percent of all

houses built on expansive soils suffer from foundationdistress. The problem occurs when only part of the foundation

leans or settles, causing cracks and other damage. This

differential movement is largely caused by differences in soil

moisture. Loss or gain of soil moisture can cause serious

shrinkage or swelling.


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CHAPTER THREE

METHODOLOGYThis aspect of the work will describe the complete activities

that are to be undergone. The house plane is shown below.

The production activity will include the time and cost.

TAKE OFF SHEET

SUB-STRUCTERE ACTIVITIES

1. Site clearance2. Setting out3. Excavation of trench4. Foundation concrete footing5. Foundation block work6. Backfilling & compaction7. Hardcore filling8. Formwork9. Over site concrete

1. Site clearance

Removal of top soil not exceeding 300mm deep and cart away with trust

from site.

Length - 11.87Add - 3.00 14.87 x 14.24 = 212.5m

2

14.87

Width - 11.24

Add - 3.00

14.24


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2. Setting out

External girth - 46.2m2

Internal (horizontal) - 20.08m2

Internal (vertical) - 20.70m2

Total - 86.98m2

3. Excavation of trench

Girth

External girth - 2 x 11.9 = 23.8m

2 x 11.2 = 22.4m

46.2m

Internal girth - 20.08m

Vertical - 20.70m

Total girth - 46.2m

23.8m

+ 22.4m

86.98

Length - 86.98m

Width of trench - 0.68m 53.23m3

Depth of trench - 0.90m


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4. Foundation footing

0.68

0.90

0.15

Length - 86.98m

Width - 0.68m 8.87m3

Depth - 0.15m

5. Foundation block work

0.90 0.75

0.15

0.68

Length of block- 85.98m

Height of block - 0.75m65.24m

2


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6. Back filling

0.30m

0.68

Length -11.90m

Width - 11.20m 39.98m3

Depth of backfilling - 0.30m

7. Hard core

0.30

0.30

0.68m

Length -11.90m

Width - 11.20m 39.98m3

Depth of hard core - 0.30m

Earth filling

Hard core

Earth fill


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8. Form work

Sawn timber plank to both side of the top.

2 x 11.90 =23.8m

2 x 11.20 =22.4m

46.2m

Length of timber plank = 46.2m

Width of timber plank = 0.25m

9. over site concrete

Concrete of 1:2:4 -20mm aggregate well compacted, place to avoid

segrement of concrete

0.15m

0.30m

0.30m

0.15

Length -11.90m

Width - 11.20m 19.9m3

Depth of concrete0.15m

Hard core

Earth filing

11.55m2


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WORK FORCE AND TIME

Site clearance

From table, Grader capacity 10,000m

2

/day

Site area to clear = 212.5m2

Therefore, 1day is required (1 operator, 1 banks man)

Setting out

Requires 1 day (1 engineer, 1 labour)

Excavation of trench

Maximum depth not exceeding 0.9m, requires 2.20hr/labour/m2

Therefore, 53.23m3

x 2.20hr/labour/m2

= 117.10hr

Work hour of labour/day = 8hr

1178 =14.63, approximately15 days for one unskilled labour.

155 = 3, 5 unskilled labour will excavate trench for 3 days

Foundation footing

Foundation concrete footing of 150-300 thick, requires 4.30hr/m2for

1 unskilled labour.

8.87m3

x 4.30hr/m2

=38.14hr


38.148 = 4.76, approximately 5days for one mason and 1 unskilled

labour.

2 labourers, 2 masons will complete concrete footing in 2 days.


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Foundation block work

230mm hollow sandcrete block joint with mortar of 1:3 requires

1mason and 1labour for 10m2of block/day.

Total area of block work = 65.24m2

65.2410 = 6.52, approximately 6 days for 1 mason and 1 labour

62 =3, 2 mason and 2 labourers will complete block work for 3 days

Back fillings

Required 1.5hr/m

3

39.98m

3x 1.50 =59.97hr

8hr required/day for 1 labour

59.978 =7.49, approximately 8 days for 1 labour

84 =2, 4 labourers will complete back filling for 2days

Hard core

Ditto

Form work

0.45hr/m2

11.55m2

x 0.45hr = 5.1975hrs


Requires 1 carpenter and 1labour to complete form work

Over site concrete

2.50hr/m3


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FOUNDATION PRODUCTION ACTIVITES TABLE

Task name Area(m

2)

Volume(m

3)

Hours ofwork (hr)

Requiresday of wk

Cost(N)

Site

clearance 212 3 1 25,000

Setting out

59.5 4 1 1000

Excavation

of trench 53.2 117 3 15000

foundation

footing 8.87 38 2

10000

Foundation

block work 65.2 52 3 15000

Back filling

&

compaction

39.98 59 2 8000

Hard core 39.98 60 2 8000

Form work 11.55 5 1 2500

Over site

concrete 199 50 1 9000

Total 16 days 73,500


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0

0.5

1

1.5

2

2.5

3

3.5

Numberofdays

Task Name

Graph of Task against Number of days


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0

5,000

10,000

15,000

20,000

25,000

30,000

Cost(Naira)

Task name

Graph of Cost against Task


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CHAPTER FOUR

SUMMARY OF FINDINGS

From the research findings, it can be deduced that the use of glass building is

quite economical provided aesthetics is also considered.

REFERENCE

Adeshoga, I. E (2002) glass as a structural material, Longman Lagos

Mechanical properties glass by R K Brow

Horst Scholze: "Glass - Nature, Structure, and Properties"; Springer, 1991, ISBN

0-387-97396-6

Steve W. Martin, Ph.D., Professor of Materials Science and Engineering,

Iowa State University.

R. W. Douglas: A history of glassmaking, G T Foulis & Co Ltd, Henley-

on-Thames, 1972, ISBN 0854291172

BY OJO EMMANUEL

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case study on block foundation productivity

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