In this research we are discussing the argument aboutwhich type of concrete we use in fence projects, Is it the cast in situ concreteor the precast concrete, which one will has the lowest cost to the owner and remainhaving the same quality.we used this method to set the suitable solution as itcompares between the two solutions according to cost, time and quality.
Our case study is about a fence surrounding a residentialcompound; the fence consists of 3 phases with total length 1.22 kilometer andmax height 3 meter from ground levelThe fence was studied in two cases:1- Precast concrete consists of (columns – separatefoundations – intermediate panels)2- Cast in situ cantilever retaining wall In this paper we found that the precast concrete will be thecheapest solution and the highest quality. II. IntroductionAs the Precast became a new technique and can fighthardly in the market, therefore we had to study it in different projects andcompare it with the old technique (cast in situe ) to prove who is the winner. may be cast in situwins in some projects as we know nothing is always right and in some projectsPrecast is preferable So, we are showing a real case study for a fence project thatwas constructed in one of the residential compounds.Precast concrete became one of the most important concreteproducts, many of the products now are made from it like (walls – slabs – stairs- cladding panels – fences – manholes – hollow cores – waiting seats – soundwalls ..
… and many other products).Precast require high control to achieve the needed quality, because it is a final product which doesn’t need any addition touches in thesite as everything can be made in the factory . III. ResearchPurpose The purpose of this paper knows which method in constructionwill be optimum and more efficient and saves money, time and verifies thehighest quality.
Also it will be a methodology proposal to the constructioncompany to evaluate the fences projects construction.This paper will be a guide for who want to use valueanalysis methodology, as we here comparing between 2 alternatives, so we areshowing every one’s value and cost and then compare between them according tocertain merits. 1. What is Value Analysis?Value analysis is the process which the product or theproject is well defined to know its function and through this study we searchfor the alternatives which reduce its cost (life cycle cost) without affects its valueand quality, and also try to improve the quality.During studying the project, applying the value analysisis much more effective in the early time of it and it will be easy to be doneas the project is in the beginning so the ability of change will increase, andby the time it will be difficult to do any changes.But also studying of the alternatives will be importantwhatever the status of the project because it will be useful in studying thenext projects and will help the management to take the important decisions andavoid the last mistakes.
Applying value analysis in different stages of the projectand its impact on money 2. Value analysis historyAs we know that the need is the mother of invention,Value analysis is also came from a need, as in the world war II (VA) began inan electric company, and due to the shortage of resources (money and manpower andSkills), they had to find a way to get through this abstracts and find new waysto reduce cost, and also developed materials to overcome the lack of the neededones. As they applied the new technique they find out greatbenefits of reduced cost with the same performance, so it turned from a need toa systematic and logical way of thinking in most of fields and it applied nowin many companies. To make value analysis to a certain investment, there aresome important tools and expressions must be known before to facilitate theanalysis, like:1. Life cycle cost2. qualityEvaluation3.
Value Index And these are the three main steps to make any value analysisfor any project or product 1. Life cycle costAny project or material or a machine has life cycle cost.Lifecycle is studying the cost of the Project or material or machine during the it’slife time, which is the time when it will perform and apply the it’s job beforeit is stop doing thatLifecycle cost includes:• Initial cost”capital cost” (equipment cost – legal fees – buildings cost)• Maintenance cost• Operation cost(Direct cost and indirect costs)• Risk cost The life cycle span must be the time when the investorhas interest in the investment, and it is not necessary be the real life timeof the investment. As we go for life cycle cost, there is an important point to talk aboutwhich is the time value of money.Time value of money is the value of money in different times either it is in thepast or in the future , It is the tool which enable us to know the real valueof money and judge the investment .This tool is very important in taking decisions especially in feasibilitystudies before the investment start. 2.
Quantifying quality It is turning the quality which is non quantitative into a measurablenumerical value, thus we can compare to life cycle cost and make calculationneeded Quantifying quality is very important step and it affect directly thedecision making and it must deep and précised to get the best solution between thealternatives.To quantify quality we have many methods for example: 1- ABC method It is used after brain storming on the ideas, as we make a table anddivide it into 3 columns (A – B – C)2- Evaluation matrix This method depends on having the alternatives and it isdone as follows: • We start setting the merits or the criteriaof choosing between the alternatives • weightingeach criterion from the total percentage.• Give a score to all alternatives in eachcriterion • Count downall the scores to each alternative This method gives accurate results to the weights to makeit easy on choosing the right choice Value IndexValue index is a number refers to best option and as itincreases for a certain alternative, the chance of choosing this alternative increases.To get the Value Index you will use the last two stepsLife cycle cost • Quantifying thequality As the Value Index = quality / cost 2. Project Issues Our concern in this project is choosing the technique of thefence either cast in situ of precast. We want to know which will cost less andhave the same quality.Taking in consideration that the fence will be retainingwall as it carry soil with difference levels and max level difference is 2000mm 1st Alterative is:Precast concrete:Precast concrete means that the concrete member is castedand cured in another place than its final place which designed to be in, it startedwith a Gardner who made some tubs and then it used in many fields.
Precast has the highest quality in finishing due to thehuge control and inspection on the mold and also the control in the process.Precast Building• Precastdoesn’t need any additional plastering or painting as it come with its finalshape to be installed and has many shapes and finishes as shown in photos . Finish Styles in precast fences• Time will be reduced as it reduces the timeof contraction.• No need formaintenance • No need forformwork only lifting Case study:Shown some photos of precast fences items: Precast Panel (Part of Shop drawing)This is the shop drawing of the panel and shows the liftersplaces and the total height of the panel and length and width and thickness The three dimension view of the panel is made with auto cadalso shown the figure of the foundation and 4 lifting hangers to move it fromplace to another Precast column All Items after putting togetherThis will be the final shape of the fence panel. Thefoundation in both directions putting on the column and filling with grout thenputting the panel in between and making this along the fence line to complete theprojectThis is a part of erection using auto cad showing thepanel name and ground level and the length of column Quantity of precast items for:For the first table which is for wall:Where the first column “Panel No” contains allof the wall types for example w1-55, w means wall, 1 is the type of the wall aswe have 4 types according to design and 55 is the wall name.The other columns “L-h-X” is shown in the figure on the leftand the last column Q means the QuantityFor the 2nd column is shows the Quantities of columns:Where the first column “column No” contains allof the columns in the line For example “c1-04”, c means column , 1 means thecolumn type as we have 4 types accordingto design and 04 is the column name The 3rd column is for foundations It consists of 2columns the 1st one “Footing no.” is the types of the footing as wehave 6 types according to design and the 2nd column is Q means quantities.
The quantities of line 2 include the columns and Foundationsand show the names and height and quantities and show a small drawing indicationabout the columns Wall quantities The table shows the quantities of the walls and names ofit on the erection drawings and also it include description for the wall”Panel” Dimensions as we explained before. the figure show the shape of column and its dimensionwhich is 300 x 300 and also the total height which is different from panel toanother and also the reinforcement of the column and its stirrups 8 ? 12 and Stirrups ? 8 @200 mm Steel And Volume calculations for wall type 1The next table gives us the no of wall 1 and its height, reinforcement,the volume and also the weight of steel The panel is drawn and gives us where the lifting is andall the dimension of the panel and what the symbols mean. The next photo is the wall reinforcement in both directionsvertical and horizontal in front view and side view which is ?10 at 200mm invertical direction and the same in horizontal with additional ?10 in thecorners of the wall Steel and Volume calculations for Foundation type 1the table is the bar bending schedule for the footing andgive us the shape of the steel bars and no of it and all the reinforcementissues to help in getting the volume of the steel on the foundation . It contain manyshapes about 11 different type of bars and all of it its quantity in the footingand the lengths and this quantities are multiplied to the no of footing to giveus the total volume.
Part 2Cast In Situ Design:Cast in situ is the traditional way to install concrete structureswhich depends on installing form works then steel then pouring the concrete allof this is done in the site. After pouring the concrete plastering and painting worksstart.We started designing a retaining wall to carry thedifference in soil. Cast in SituUsing the Retaining wall, the design was made according tothis case which is the critical case in the project.
Cost of Precast FenceIn Precast fence we are checking the cost in 3 main locations:1st location is the cost inside the Factory which include the laborcost and material cost and the lifting cost from factory to the backyard The 2nd location is the transportation which is moving thepanels from the factory to the site which need trucks and need to know thevolume which we transport The 3rd location is at site where the panels will be usedand install as we calculate the cost of labor and carne and Engineers. Thisdocument will give us the total cost and the items cost.Cost of Retaining wall FenceTo know the cost of the retaining wall the situation isdifferent from the precast cost as here we are calculating the cost of materialand labors andif there is other additional items like painting.Fence – Pricing If the time Schedule is the same in both of the methodsand see the results we find that using the retaining wall is not the preferablesolution to overcome the soil difference as we can use the precast fence whichwill cost 2 million LE while the retaining wall will cost 3 million LE , So we can Save about 1 million which will beabout 34% saving and this is a great money to save life cycle cost :Our life cycle span is 60 years According to thatproject life cycle cost will be the 10 years maintenance and Paining And this will be applied for both alternatives If the productivityof 1 crew of painters is 500m2/day by the cost is 400 LE and our fence is4880m2 Our duration is 4880/500 = 10 daysThe cost of paining the fence is 10 x 400 = 4000 LEIf the Interest rate is 20%this is the schedule of the retaining wall fence projectshowing the activities which will be done like : carpentering of footing – steelwork of footing – concrete casting- carpentering of wall – steel work of wall –concrete casting – painting The total duration of the project is 155 working days andsome of activities are finish to start and also there is buffer between activitiesand each other