1.0.INTRODUCTION Consideringhow building materials constitute a large percentage of the total buildingcost, 65-70%, as stated by Ashworth (2004) and Yalley and Kwan (2008), thechoice 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 canaid in achieving lower final building cost.
With the focus being on commercialbuildings, the effect of choice of materials becomes more pronounced as thequantity of materials on commercial buildings are high due to the nature ofcommercial building projects. This brings about the need for cheaper longlasting materials. The Latham report comments on the link between initial andfuture 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 costsin use. The energy and maintenance equations should be uppermost in the mindsof the designer and client as well as the appearance of the façade and theeffective use of space” (1994).
The report notes, however, that paying a highprice, in itself, does not guarantee quality. Oneof the many reasons why building materials are costly in Zambia, can beattributed to the fact that most of them are imported and those that aremanufactured locally still have their raw materials imported (Danso, 2013). Inaddition there is a high level of use of concrete blocks on commercialbuildings as well as residential buildings, this is based on informationobtained from viewing a number of bills of quantities for various projects atthe PBE’s (Public Buildings Engineers) office in Lusaka. This extensive use isattributed to the seemingly low cost of a concrete block.
Concrete MasonryUnits (Concrete blocks) prove to be time consuming due to its highly labourintensive nature, according to Understanding building construction (2017), aswell as high cost associated with scaffolding on structures with heightsexceeding 2 meters. Glass and steel are also materials used for walling inZambia, however, as earlier mentioned, imported goods tend to have highprices. Theaim of this research is to establish if the use of Tilt-Up concreteconstruction could be adopted in the Zambian construction industry and addvariety to the available choices of construction. Mainly to aid in facilitatingfaster construction times as well as achieving economic cost of construction mainlyfor 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-Upconcrete Association (2005) that this type of construction method is suitablefor commercial buildings. 2.0.WHATIS TILT-UP CONCRETE CONSTRUCTION?Asstated by the Tilt-Up Concrete Association (2005) the term “Tilt-Up” was coinedin the late 1940’s to describe a method for constructing concrete rapidly andeconomically without the formwork necessary for poured in-place walls.
Tilt-Upis also called “tilt-wall” or in specifications and technical papers,”site-cast precast concrete walls” (Tilt-Up Concrete Association, 2005). American Concreteinstitute Committee 551 (2003) describes Tilt-Up as the technique ofsite-casting wall panels on a horizontal surface and then lifting or tiltingthem into place. Basically tilt-up is a method of casting building walls on ahorizontal surface, waiting for a sufficient time for concrete to gain strengthand then tilting the panel up into its final position using a crane. It is alsodescribed, by Construction World Magazine November (2013) issue, as aconstruction technique where the elements are cast on site and lifted intotheir final position, maximizing many of the unique and sustainable benefits ofconcrete for a cost effective building technique and efficient constructionmethod.
The wall panel is cast on a flat surface and it is simply not a solidwall with no openings, tilt-up panels have the advantage of incorporatingopenings for doors, windows and generic openings alike before the panel can belifted into place, this allows for time saving when it comes to forming ofopenings as once they are cast all that remains is to let the concrete gainsufficient strength and tilt the panel up into position (Tilt-Up Concrete Association, 2005). Thistype of construction is used in countries such as the United States, Canada,New Zealand and Australia successfully as a walling system as well as aconstruction method. The number of tilt-Up buildings constructed annually issignificantly increasing and one of the factors contributing to this growth isthe acceptance of tilt-up as a more creative design and construction medium anda factor for nearly all market types (Tilt-Up Concrete Association, 2005).
InCanada this type of construction has been in use for many years helping to pushthe construction method into new territory (Dispenza, 2014). Tilt-Up is mainlyused on commercial building projects such as schools, warehouses, shoppingcenters, multistory office blocks sports halls and many other commercial typebuildings (Jay-Ton Concrete Construction, 2016). 2.1. WHY TILT-UP?Tilt-Upconstruction provides numerous advantages over steel buildings or traditionalconstruction for warehouses, call centers, retail stores, office buildings,storage facilities and other types of industrial and commercial buildingconstruction projects and according to Jay-ton Concrete construction (2016)some of the Advantages include: i.
Saving in construction costs: Providesnumerous construction cost savings. This method of concrete uses locallyavailable materials rather than ones that have to be shipped in. Tilt-Up workcrews are typically smaller than crews used in traditional construction and arenormally comprised of local labor; ii. Fast Construction Schedule: Erecting thewalls with Tilt-Up panels is faster than building walls using traditionalconstruction techniques. The trades can begin work earlier in the process on aTilt-Up project, which allows greater overlapping of project phases. Because the building is made of ready mixConcrete opportunities for delays and cost overruns are reduced; iii. Tilt-Up concrete is a proven safe methodof construction. Vast majority of project takes place on the ground thus lessneed for scaffolding reducing risks; iv.
Tilt-Up concrete buildings are notprefabricated but they can be considered as a type of on-site prefabricated componenteliminating the need for a factory. This allows for use without the need toconstruct a factory thus, allowing it to retain advantages of prefabricatedsystem. Tilt-upis a form of site cast prefabrication, where concrete wall panels are cast on-siteand tilted into position, and is one of the fastest growing constructionmethods used around the world today. This type of construction offers costeffective, energy efficient, durable building with plenty of architecturalversatility and curb appeal, it is becoming the building method of choice foreverything from ware houses and industrial facilities to office buildings,movie theatres and schools (Tiltwall INC, 2017).
Tilt up concrete constructionis known to work best for commercial building but there have been advancetowards using tilt up for smaller buildings and as an example the researchconsidered a 2,700 square foot three and a half story building in Halifax, Novascotia, which was successfully built even though the space was confined.According to For Construction Pros (2013), this was achieved by melding up tiltup and traditional steel clad methods together. The client achieved a uniquelook to the structure as well as an efficient construction timeline (For Construction Pros, 2013).
Figure1.1. shows the cost of various wall systems and their costs per square foot inAmerican Cities. The purpose of this table is simply to have a look at howcompetitive Tilt-Up is compared to other wall systems in America. Fig1.1 Cost per square foot of various types of wall systems in USA (CapitalBuilding Consultants, 2014).Thistable simply shows that even in technologically advanced nations Tilt-Up isstill the cheaper option in terms of wall system as compared to CMU and MetalBuildings. 3.
0.PROBLEM JUSTIFICATIONConcreteblocks prove to be the material of choice when building smaller units of housesand can even prove economical when skilled bricklayer are employed. Theseskilled brick layers are able to construct a medium cost house within a fewweeks and at minimum cost. But when it comes to multi story buildings, andlarge areas, block work begins to prove costly and time consuming. Some disadvantagesof Masonry according to Understanding Building Construction (2017) include: i. It is extremely labour intensive, as itis built of masonry, which is made by hand. This also makes for very slowconstruction speeds in comparison with modern methods that are far moremechanized; and ii. It is extremely material intensive.
These buildings consume a lot of bricks and blocks, and are very heavy. Thismeans that they are not green, as all this material has to be trucked aroundfrom where it is produced to site. Afew examples of the time it takes for block work to be completed onconstruction projects in Zambia can be considered in the case of the followingprojects: 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 blockwork on the first and second floors, this is excluding plastering andconduiting (F.C. Luwaya, 2017, pers.comm, 8 November). ii. A 400m2 single storystructure in Chongwe took 3 months for all block work to be completed, alsoexcluding plaster and conduits according to Mr. Mukuka Chisanga, a QuantitySurveyor at MLN associates, interviewed on 8 November (F.
C. Luwaya, 2017,pers.comm, 8 November). iii. Mr Chisanga also gave an example of atraining center done by MLN associates that had a total area of 1500m2and this structure took 15 to 18 weeks to completely enclose using block work. iv. MLN associates is a quantity surveyingfirm in Lusaka. Asidefrom the use of concrete blocks, the use of Steel as a walling system as wellas structural material is also practiced in Zambia.
Steel is an excellentmaterial for smaller buildings under 50, 000 square feet (approx. 4126 meterssquare) because of the labour and equipment required for concrete tilt-upstructures. This is true despite the lower overall cost of steel compared toconcrete, bear in mind that this is according to UK construction industry wheresteel 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 concreteaccording to Future Steel Buildings (2013). However, an article by Bob MooreConstruction INC states, regardless of which traditional approach to wallconstruction is used, steel wall or CMU, building the exterior wall is a timeconsuming multi stepped process. Thus stating the complete opposite as to thestepped of construction using steel walls. Steel is generally more expensive ascompared to concrete and this is more prevalent in Zambia as there is a smallnumber of a steel manufacturers resulting in high cost of steel due toimportation. A journal by DLS consultancy (2008) also stated, after carryingout a case study to determine the cost difference between concrete and steel structures,the cost of reinforced concrete structure was lower than that of steelstructure.
This was despite the fact that prices of ready-mixed concrete haveincreased tremendously over the past year or so due to the sand ban imposed byIndonesia. As already seen in Fig 1.1 this is a table showing the various costof 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 metalbuildings per square meter, taking into account the fact that the United Statesof America is far more technologically advanced in terms of steel manufacturingthan Zambia. Toshow a basic comparison of Tilt-Up and CMU (concrete masonry units) wallconstruction a simple calculation has been done to show the differences in timeand cost. A building of overall area 70 x 70 meters and a height of 8 meterswill be used as an example. 3.1.BLOCKWORK 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 Table1.1.
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 atk30/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 brickforce vi. Scaffolding Cost per week for 100 metersquare (Rate obtained from Waco industries) = k 3, 260.
293.2.TILT-UPCONCRETE 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 Table1.2. Time and cost estimate of using Tilt-Up concrete construction. i. Crane (rate obtained from mega earthmovers 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 gainenough 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 shelland completely enclose structure. FromTables 1.1. and 1.
2. it is observed that Tilt-Up can wall panels can be erectedto 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. Whenit comes to the use of metal building it is determined by the availability ofsteel manufacturers locally and the availability of funding as can be seen inAnnex Company list, there are only a few companies that manufacture steel andthe steel is of limited type. 4.
0.PROBLEMSTATEMENTTheContinued use of traditional construction materials and methods, such as CMUand Steel, results in either high costs, long periods of erection or both. 5.0.HYPOTHESISUseof tilt-up concrete construction can reduce on time spent erecting buildingwalls as well as cost of construction. 6.0.AIMToinvestigate and determine if the use of tilt-up concrete construction canfacilitate efficient construction in the Zambian construction industry 7.
0.OBJECTIVESTheobjectives of this study include: i. Determining the expertise needed tosuccessfully carry out Tilt-Up construction; ii. To determine if the conventionalconstruction methods and materials pose a problem of high cost and lengthyperiods of construction; iii. To determine the cost implication ofadopting Tilt-Up construction in Zambia. 8.0.
ANNEX AnnexTable 1.1. Imports and exports of steel in Zambia. AnnexTable 1.2. List of Companies that provide steel.
( Zambia Development Agency,2012). 9.0.REFERENCESACICommittee 551, (1992). Tilt-Up ConcreteStructures (ACI551R-92). American Concrete institute, Farmington Hills, MI.Ashworth,A.
, 2004. Cost studies of Buildings.4th ed. London: Pearson Education Limited.BobMoore Construction INC, (n.
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Tilt-Up construction for cost-effective aesthetics anddurability, Construction World: TheBusiness Magazine for the Construction Industry pdf Available at: www.crown.co.za/reader/DLSConsultancy, (2008). VIABILITY OF THEADOPTION OF STEEL AS A SUBSTITUTE FOR CONCRETE AND ITS IMPACT ON SUSTAINABILITY.
8 (3) pp. 1-6. ForConstruction Pros, 2013. Tilt-Up ConcreteMethod Proves Successful in Small Building Footprint.
Online Availableat:www.forconstructionpros.com/bussines/article/11152106/tiltup-concrete-method-proves-successfull-in-small-building-footprintJay-TonConcrete construction, (2016). 4 ReasonsContractors Choose Tilt-Up Concrete Construction. Online Available at:www.jay-ton.com/single-post/2016/08/23/4-Reasons-Contractors-Choose-Tilt-Up-Concrete-constructionAccessed 13 October 2017LucasKlock, (2005).
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