1.0. choice of materials becomes more pronounced as

1.0.
INTRODUCTION

Considering
how building materials constitute a large percentage of the total building
cost, 65-70%, as stated by Ashworth (2004) and Yalley and Kwan (2008), the
choice in material can have an adverse effect of the final building cost. Thus,
employing the use of materials that are relatively cheaper and long lasting can
aid in achieving lower final building cost. With the focus being on commercial
buildings, the effect of choice of materials becomes more pronounced as the
quantity of materials on commercial buildings are high due to the nature of
commercial building projects. This brings about the need for cheaper long
lasting materials. The Latham report comments on the link between initial and
future costs noting that “good design does not necessarily involve high cost.
Good design will provide value for money in terms of both total costs and costs
in use. The energy and maintenance equations should be uppermost in the minds
of the designer and client as well as the appearance of the façade and the
effective use of space” (1994). The report notes, however, that paying a high
price, in itself, does not guarantee quality.

One
of the many reasons why building materials are costly in Zambia, can be
attributed to the fact that most of them are imported and those that are
manufactured locally still have their raw materials imported (Danso, 2013). In
addition there is a high level of use of concrete blocks on commercial
buildings as well as residential buildings, this is based on information
obtained from viewing a number of bills of quantities for various projects at
the PBE’s (Public Buildings Engineers) office in Lusaka. This extensive use is
attributed to the seemingly low cost of a concrete block. Concrete Masonry
Units (Concrete blocks) prove to be time consuming due to its highly labour
intensive nature, according to Understanding building construction (2017), as
well as high cost associated with scaffolding on structures with heights
exceeding 2 meters. Glass and steel are also materials used for walling in
Zambia, however, as earlier mentioned, imported goods tend to have high
prices. 

The
aim of this research is to establish if the use of Tilt-Up concrete
construction could be adopted in the Zambian construction industry and add
variety to the available choices of construction. Mainly to aid in facilitating
faster construction times as well as achieving economic cost of construction mainly
for walling systems as compared to the existing block work and steel systems.
This is with respect to commercial buildings as it is stated by the Tilt-Up
concrete Association (2005) that this type of construction method is suitable
for commercial buildings.  

2.0.WHAT
IS TILT-UP CONCRETE CONSTRUCTION?

As
stated by the Tilt-Up Concrete Association (2005) the term “Tilt-Up” was coined
in the late 1940’s to describe a method for constructing concrete rapidly and
economically without the formwork necessary for poured in-place walls. Tilt-Up
is also called “tilt-wall” or in specifications and technical papers,
“site-cast precast concrete walls” (Tilt-Up Concrete Association, 2005). American Concrete
institute Committee 551 (2003) describes Tilt-Up as the technique of
site-casting wall panels on a horizontal surface and then lifting or tilting
them into place. Basically tilt-up is a method of casting building walls on a
horizontal surface, waiting for a sufficient time for concrete to gain strength
and then tilting the panel up into its final position using a crane. It is also
described, by Construction World Magazine November (2013) issue, as a
construction technique where the elements are cast on site and lifted into
their final position, maximizing many of the unique and sustainable benefits of
concrete for a cost effective building technique and efficient construction
method. The wall panel is cast on a flat surface and it is simply not a solid
wall with no openings, tilt-up panels have the advantage of incorporating
openings for doors, windows and generic openings alike before the panel can be
lifted into place, this allows for time saving when it comes to forming of
openings as once they are cast all that remains is to let the concrete gain
sufficient strength and tilt the panel up into position (Tilt-Up Concrete Association, 2005). 

This
type of construction is used in countries such as the United States, Canada,
New Zealand and Australia successfully as a walling system as well as a
construction method. The number of tilt-Up buildings constructed annually is
significantly increasing and one of the factors contributing to this growth is
the acceptance of tilt-up as a more creative design and construction medium and
a factor for nearly all market types (Tilt-Up Concrete Association,
2005).
In
Canada this type of construction has been in use for many years helping to push
the construction method into new territory (Dispenza, 2014). Tilt-Up is mainly
used on commercial building projects such as schools, warehouses, shopping
centers, multistory office blocks sports halls and many other commercial type
buildings (Jay-Ton Concrete Construction, 2016). 

2.1. WHY TILT-UP?

Tilt-Up
construction provides numerous advantages over steel buildings or traditional
construction for warehouses, call centers, retail stores, office buildings,
storage facilities and other types of industrial and commercial building
construction projects and according to Jay-ton Concrete construction (2016)
some of the Advantages include:

       i.         
Saving in construction costs: Provides
numerous construction cost savings. This method of concrete uses locally
available materials rather than ones that have to be shipped in. Tilt-Up work
crews are typically smaller than crews used in traditional construction and are
normally comprised of local labor;

     ii.         
Fast Construction Schedule: Erecting the
walls with Tilt-Up panels is faster than building walls using traditional
construction techniques. The trades can begin work earlier in the process on a
Tilt-Up project, which allows greater overlapping of project phases.  Because the building is made of ready mix
Concrete opportunities for delays and cost overruns are reduced;

   iii.         
Tilt-Up concrete is a proven safe method
of construction. Vast majority of project takes place on the ground thus less
need for scaffolding reducing risks;

   iv.         
Tilt-Up concrete buildings are not
prefabricated but they can be considered as a type of on-site prefabricated component
eliminating the need for a factory. This allows for use without the need to
construct a factory thus, allowing it to retain advantages of prefabricated
system.

Tilt-up
is a form of site cast prefabrication, where concrete wall panels are cast on-site
and tilted into position, and is one of the fastest growing construction
methods used around the world today. This type of construction offers cost
effective, energy efficient, durable building with plenty of architectural
versatility and curb appeal, it is becoming the building method of choice for
everything from ware houses and industrial facilities to office buildings,
movie theatres and schools (Tiltwall INC, 2017). Tilt up concrete construction
is known to work best for commercial building but there have been advance
towards using tilt up for smaller buildings and as an example the research
considered a 2,700 square foot three and a half story building in Halifax, Nova
scotia, which was successfully built even though the space was confined.
According to For Construction Pros (2013), this was achieved by melding up tilt
up and traditional steel clad methods together. The client achieved a unique
look to the structure as well as an efficient construction timeline (For Construction Pros, 2013).

Figure
1.1. shows the cost of various wall systems and their costs per square foot in
American Cities. The purpose of this table is simply to have a look at how
competitive Tilt-Up is compared to other wall systems in America.

 

Fig
1.1 Cost per square foot of various types of wall systems in USA (Capital
Building Consultants, 2014).

This
table simply shows that even in technologically advanced nations Tilt-Up is
still the cheaper option in terms of wall system as compared to CMU and Metal
Buildings.

 

3.0.
PROBLEM JUSTIFICATION

Concrete
blocks prove to be the material of choice when building smaller units of houses
and can even prove economical when skilled bricklayer are employed. These
skilled brick layers are able to construct a medium cost house within a few
weeks and at minimum cost. But when it comes to multi story buildings, and
large areas, block work begins to prove costly and time consuming. Some disadvantages
of Masonry according to Understanding Building Construction (2017) include:

       
i.         
It is extremely labour intensive, as it
is built of masonry, which is made by hand. This also makes for very slow
construction speeds in comparison with modern methods that are far more
mechanized; and

     
ii.         
It is extremely material intensive.
These buildings consume a lot of bricks and blocks, and are very heavy. This
means that they are not green, as all this material has to be trucked around
from where it is produced to site.

A
few examples of the time it takes for block work to be completed on
construction projects in Zambia can be considered in the case of the following
projects:

       i.         
When interviewed on November 8 Mr.
Jephthah Phiri an architect stated that St Mary’s two story classroom block
(the building is a 52 x 11m two story building) took 6 weeks to complete block
work on the first and second floors, this is excluding plastering and
conduiting (F.C. Luwaya, 2017, pers.comm, 8 November).

     ii.         
A 400m2 single story
structure in Chongwe took 3 months for all block work to be completed, also
excluding plaster and conduits according to Mr. Mukuka Chisanga, a Quantity
Surveyor at MLN associates, interviewed on 8 November (F.C. Luwaya, 2017,
pers.comm, 8 November).

   iii.         
Mr Chisanga also gave an example of a
training center done by MLN associates that had a total area of 1500m2
and this structure took 15 to 18 weeks to completely enclose using block work.

   iv.         
MLN associates is a quantity surveying
firm in Lusaka. 

Aside
from the use of concrete blocks, the use of Steel as a walling system as well
as structural material is also practiced in Zambia. Steel is an excellent
material for smaller buildings under 50, 000 square feet (approx. 4126 meters
square) because of the labour and equipment required for concrete tilt-up
structures. This is true despite the lower overall cost of steel compared to
concrete, bear in mind that this is according to UK construction industry where
steel proves to be cheaper than concrete. In buildings over 50,000 square feet,
however, the cost of construction is offset by the cheaper price of concrete
according to Future Steel Buildings (2013). However, an article by Bob Moore
Construction INC states, regardless of which traditional approach to wall
construction is used, steel wall or CMU, building the exterior wall is a time
consuming multi stepped process. Thus stating the complete opposite as to the
stepped of construction using steel walls. Steel is generally more expensive as
compared to concrete and this is more prevalent in Zambia as there is a small
number of a steel manufacturers resulting in high cost of steel due to
importation. A journal by DLS consultancy (2008) also stated, after carrying
out a case study to determine the cost difference between concrete and steel structures,
the cost of reinforced concrete structure was lower than that of steel
structure. This was despite the fact that prices of ready-mixed concrete have
increased tremendously over the past year or so due to the sand ban imposed by
Indonesia. As already seen in Fig 1.1 this is a table showing the various cost
of building per square meter using different materials in American countries.
It can be noted that tilt-up is cheaper than block work as well as metal
buildings per square meter, taking into account the fact that the United States
of America is far more technologically advanced in terms of steel manufacturing
than Zambia.

To
show a basic comparison of Tilt-Up and CMU (concrete masonry units) wall
construction a simple calculation has been done to show the differences in time
and cost. A building of overall area 70 x 70 meters and a height of 8 meters
will be used as an example.

 

 

3.1.BLOCK
WORK TIME AND COST ESTIMATE

Item

Block
work and plaster cost (K/m2)

Brick
force cost (K/m)

Scaffolding
cost (K/month)

Coverage
m2 (Block work and plaster)

Covergage
m (Brick force)

Duration
(Scaffolding)

Cost
(K)

Block
work (8″)

200.00

 

 

2240

 

 

492,800.00

Plaster
(internally and externally)

35.00

 

 

4480

 

 

156,800.00

Scaffolding
(hired)

 

 

292,096.00

 

 

1 month 4days

408,934.40

2m
Brickforce

 

5.00

 

 

3640

 

18,200.00

Total

 

 

 

 

 

 

1,076,734.00

Rate
k/ m2

 

 

 

 

 

 

486.00

 

 

 

 

 

 

 

 

Item

Hours/m2

 

 

Area
to be covered m2

 

 

Time
(Hours)

Block work (8″) 10 brick layers

1.33/brick layer

 

 

2240

 

 

224

Plaster (internally 13mm and
externally 19mm) 15 bricklayers

1.89

 

 

4480

 

 

565

Item

Hours/m

 

 

Area
to be covered

 

 

Time (hours)

Scaffolding (time to erect 8 meters
high) 1 supervisor & 5 fixers

5

 

 

2240

 

 

22

 

 

 

 

 

 

 

 

Total time

 

 

 

 

 

 

811

Table
1.1. Time and cost estimate of using block work

       i.         
Perimeter = 70 + 70 + 70 + 70 =
280meters

     ii.         
280m x 8m (height) = 2, 240m2

   iii.         
Add internal and external plaster at
k30/meter square

   iv.         
Brick force laid every third course
(height is 8, 000mm) = 8, 000/600 = 13layers of brick force

     v.         
13 layers x 280m = 3, 640meters of brick
force

   vi.         
Scaffolding Cost per week for 100 meter
square (Rate obtained from Waco industries) = k 3, 260.29

3.2.TILT-UP
CONCRETE TIME AND COST ESTIMATE

Item

Cost
(K) per m3

Cost
(K) per Hours

Cost
(K) per kg

Coverage
(m3)

Crane
(hours spent on site)

Total
weight of steel  (kg)

Cost
(K)

Pre-mix concrete 8″ (grade 25) m3

1,200.00

 

 

448

 

 

537,600.00

55
ton Crane

 

1,500.00

 

 

24

 

45,000.00

Y12 steel reinforcement

 

 

18.00

 

 

7722

138,996.00

Item

Cost
(K) per m3

Cost
(K) per Hours

Cost
(K) per kg

Coverage
(m3)

Crane
(hours spent on site)

Total
weight of steel  (kg)

Cost
(K)

 

 

 

 

 

 

 

 

Total

 

 

 

 

 

 

721,596.00

Rate
k/m2

 

 

 

 

 

 

322.00

 

 

 

 

 

 

 

 

Item

 

 

 

Coverage (m2)

Coverage (m)

 

Time (hours)

Pouring
of concrete

 

 

 

2240

 

 

48

Placement
of steel

 

 

 

2240

 

 

48

Placement
of formwork

 

 

 

 

1178

 

48

Curing
of concrete

 

 

 

 

 

 

240

Tilting
up panels

 

 

 

 

 

 

24

 

 

 

 

 

 

 

 

Total

 

 

 

 

 

 

408

Table
1.2. Time and cost estimate of using Tilt-Up concrete construction.

       i.         
Crane (rate obtained from mega earth
movers in Lusaka for a 55 tonne crane)

Note:
the crane company begins charging from the yard on an hourly basis.

     ii.         
Each panel 200mm thick and 57m square
(weighs 29 tonnes each)

   iii.         
Crew can lift up to 30 panels a day.
This structure will require 2240/57= 39 panels

   iv.         
It takes 10 Days for concrete to gain
enough strength to be tilted into place, and 2 days to erect all panels
(30/day), and a week to lay form work, reinforcement and conduits.

     v.         
A total of 3 weeks to form tilt up shell
and completely enclose structure.

From
Tables 1.1. and 1.2. it is observed that Tilt-Up can wall panels can be erected
to completely enclose building in half the time it would take concrete blocks.
As for the cost, use of tilt up results in savings of K355, 138.00. 

When
it comes to the use of metal building it is determined by the availability of
steel manufacturers locally and the availability of funding as can be seen in
Annex Company list, there are only a few companies that manufacture steel and
the steel is of limited type.

 

4.0.PROBLEM
STATEMENT

The
Continued use of traditional construction materials and methods, such as CMU
and Steel, results in either high costs, long periods of erection or both.

5.0.
HYPOTHESIS

Use
of tilt-up concrete construction can reduce on time spent erecting building
walls as well as cost of construction.

6.0.AIM

To
investigate and determine if the use of tilt-up concrete construction can
facilitate efficient construction in the Zambian construction industry

7.0.
OBJECTIVES

The
objectives of this study include:

       i.         
Determining the expertise needed to
successfully carry out Tilt-Up construction;

     ii.         
To determine if the conventional
construction methods and materials pose a problem of high cost and lengthy
periods of construction;

   iii.         
To determine the cost implication of
adopting Tilt-Up construction in Zambia.

 

 

 

 

 

 

8.0.
ANNEX

Annex
Table 1.1. Imports and exports of steel in Zambia.

 

Annex
Table 1.2. List of Companies that provide steel. ( Zambia Development Agency,
2012).

9.0.REFERENCES

ACI
Committee 551, (1992). Tilt-Up Concrete
Structures (ACI551R-92). American Concrete institute, Farmington Hills, MI.

Ashworth,
A., 2004. Cost studies of Buildings.
4th ed. London: Pearson Education Limited.

Bob
Moore Construction INC, (n.d). Tilt-Up Construction the Complete Article,
Online Available at: www.generalcontractor.com/constructio-resources/white-papers/tiltwall-til-up-complete.asp
Accessed 23 October 2017

Crown
Publications, 2013. Tilt-Up construction for cost-effective aesthetics and
durability, Construction World: The
Business Magazine for the Construction Industry pdf Available at: www.crown
.co.za/reader/

DLS
Consultancy, (2008). VIABILITY OF THE
ADOPTION OF STEEL AS A SUBSTITUTE FOR CONCRETE AND ITS IMPACT ON SUSTAINABILITY.
8 (3) pp. 1-6.

For
Construction Pros, 2013. Tilt-Up Concrete
Method Proves Successful in Small Building Footprint. Online Available
at:
www.forconstructionpros.com/bussines/article/11152106/tiltup-concrete-method-proves-successfull-in-small-building-footprint

Jay-Ton
Concrete construction, (2016). 4 Reasons
Contractors Choose Tilt-Up Concrete Construction. Online Available at:
www.jay-ton.com/single-post/2016/08/23/4-Reasons-Contractors-Choose-Tilt-Up-Concrete-construction
Accessed 13 October 2017

Lucas
Klock, (2005). PRE-ENGINEERED STEL
STRUCTURE VS TILT-UP CONCRETE CONSTRUCTION. pdf Washington University.
Avaiable at: www.engr.psu.edu/ae/thesis/portfolios/,
Accessed 14 October 2017

Tilt-Up
Concrete Association, (2011). THE
CONSTRUCTION OF TILT UP. Mount Vernon, Iowa: Tilt-Up Concrete Association.

TILTWALL
INC, (2017). Tilt-Up Construction vs.
Precast: What is the Difference? Online Available at:

Tilt-Up Construction vs. Precast: What is the Difference?


Accessed 14 October 2017

Understanding
Building Construction, (2017). LOAD
BEARING MASONRY CONSTRUCTION. Online Available at:
www.understandconstruction.com/load-bearing-masonry-construction.html Accessed
12 October 2017

Yalley,
P. P. &. K. A. S. K., 2008. Use of
Waste and low Energy Materials in Building Block Construction, 25th
Conference on Passive and Low Energy Architecture (PLEA) 22nd to 24th
October 2008. Dublin, s.n.

Zambia
Development Agency, (2012). Sub-sector
Profile: iron and steel. pdf Lusaka: ZDA (Zambia Development Agency.
Available at: www.zda.org.zm/%3Fq%3Ddownload/file/,
Accessed 15 October 2017