Concrete Mix Selection For Replacing Reinforced Concrete Footing In Anzac Bridge, Sydney

Performance Characteristics Required

Question:

This assignment is related to Concrete Technology and Practice. You have to finish assignment as per requirement. Here i have uploaded two files. Among one is related to assignment task and another is related to tests result data. You have analyse this data and then you have work on the assignment based on tests results. Marking criteria is also described in the assignment detail.
 

This report documents the concrete mix selection in appropriate order which is going to use instead of the reinforced concrete footing. There is a bridge structure which is damaged due to the sulphate attack and this reinforced concrete footing will be used to support the concrete towers in bridge. The bridge is located in Sydney, New South Wales and named as the Anzac Bridge where the large reinforced concrete mix will be used to replace the reinforced concrete footing which will support the concrete flanking tower at Anzac Bridge. The candidate concretes’ test data is aligned in a spreadsheet and the appropriate concrete mix is determined from candidates concrete mixes spreadsheet.

The report will try to meet the performance characteristics like checking ability of the selected concrete mix by placing into formwork section which do not have open access and also contain congested reinforcement.  Second characteristics need to meet is the ability of the reinforced concrete sections which can resist high blending movement and compressive loads. And lastly, the reinforced concrete section should accomplish the standards of AS 3600 concrete section and maintain the C2 exposure. 

This section analyzes the data provided in spreadsheet about the concrete mix and its verified through different questions. The evaluation of these questions will try to accomplish requirement and conditions through which the construction is performed. Following sections will find the appropriate data to provide the answers of asked questions: 

Description of laboratory equipment and techniques required to measure the concrete properties in the spreadsheet: 

Slump Cone, temping rod (Steel) and scale of measurement are the equipment used to measure the slump of concrete (Aburawiand Swamy, 2008, p. 110). This test measures the consistency or stiffness of concrete and it also measure concrete’s workability with the help of above equipments. Concrete’s consistency or stiffness shows water quantity used in the concrete mix.

• Frustum of cone is used in this test which is 300 mm in height and diameter of the base is 120 mm
• The base is placed on smooth surface, after that the container is filled with the concrete mix in three layers to test its workability.
• After filling the mold the top surface is rolled and screened with the help of temping rod. During entire testing the mould should be firmly held from its base so that it could not disturb while pouring concrete material.
• Immediately after filling and leveling the concrete, lift the cone slowly in vertical motion and then unsupported concrete become slump. The center of slumped concrete is decreased in height and it’s then called slump.
• Cone and temping rod is used to measure slump and decrease in height is noted with scale.

The procedure uses different types of slumps and that are based on different kinds of shapes. Different slump shape is based on the profile of the slumped concrete.

1. True Slump:Various testsuse this true slump and concrete simply subsides in this slump by keeping more or less to shape (Akinkurolere, Jiangand Shobola, 2007, p. 413).
2. Collapsed Slump: The concrete completely collapses in this type of slump. Both the concrete mix is too wet or highly workable and hence, it is not appropriate to take a slump test.
3. Shear Slump: The slump is called shear slump when one-half of the cone slides down an inclined plan.  

When it is needed to check the reinforced concretes’ strength the compressive strength test is used. The equipments required for this test are compression test machine, curing tank and balance. The formula used to calculate the compressive strength of the concrete is given below:

Compressive strength (kg/cm²) = W_f / A_p

W_f = Maximum applied load just before load, (kg)

A_p = Plan area of cube mould, (mm²)    

This test is used to compute the indirect tensile strength of concrete material. To compute this strength the ultimate load is registered first and another thing to know is dimension of the specimen, and then the indirect tensile strength of concrete material can be calculated.  The test needs to load cylindrical specimen across the circular cross section. Due to this loading a tensile deformation is caused perpendicular to that loading direction, which yields a tensile failure. 

Equipment and Techniques for Measuring Concrete Properties

This Ultrasonic pulse velocity test is performed on concrete in order to assess its homogeneity and integrity. This is a recognized non-destructive test performed on reinforce concrete. With the help of this ultrasonic test different aspects of concrete are assessed and that are given below:

1. The test assess depth of the surface cracks
2. It assess the discontinuity in cross section such as cracks in surface, cover concrete delamination and so on.
3. Qualitative assessment of concretes’ strength and concretes’ gradation in different location of structure members. 

The cylinder test performed on the freshly developed concrete is very easy and common test. In this test the cylinder of fresh consolidated concrete mix is prepared and it is used for test after certain time span.  Cylinder is used for determining strength of the specimens and the measurement of that cylinder is 150mm diameter and 300 mm height. Every lift is filled in the cylinder after resting for two minute time span. Wire ring is fixed at the top surface of cylinder with a graduated stem and one minute settlement is allowed before recording depth of penetration. The high unstable mixture has value of 1 inch and 1/6 inch for very stable mixtures. 

In order to measure the concrete properties different equipments are required. One of the significant tests for concrete measurement is air content test in concrete. The equipments like plain surface plate, Hammer, Scoop, Vessel, and Meter Gauge for pressure measuring are used to measure air content in concrete. The techniques that are used to measure air content in freshly prepared concrete are discussed here.

First, Gravimetric Method; this method used to determine the air contents in the newly prepared concrete. The batch volume or measured density in freshly prepared concrete is compared with the calculated density (Binici, 2008). Second method is Volumetric Method; the test of concrete depends on displacement of air with water in a vessel of pre calibrated volume. Next one is the Pressure Method; this method uses Boyle’s Law for measuring air content of freshly prepared concrete. According to this law volume occupied by air is directly proportional to the pressure applied to the air. Chace Air Indicator Method; Hand held device is used in this method and collected air is liberated from small fraction of mortar. 

Conclusion:

The report used the concrete data from spreadsheet and then determines the appropriate concrete mix is from concrete mixes spreadsheet. At very first report discussed about the equipment and techniques used to measure the different concrete properties given in spreadsheet and then that properties are used to determine different performance characteristics. The features are determined which help in enhancing the properties of a reinforced concrete member, whose surfaces is in contact with the ground and seawater.  

References 

Aburawi, M. and Swamy, R. N. 2008. Influence of salt weathering on the properties of concrete. The Arabia Journal for Science and Engineering, 33(N 1B): 105–115.  

Akinkurolere, O. O., Jiang, C. and Shobola, O. M. 2007. The influence of salt water on the compressive strength of concrete.Journal of Engineering Applied Science, 2(2): 412–415. 

Binici, H. 2008. Performance of ground blast furnace and ground basaltic pumice concrete against seawater attack.Construction and Building Materials, 22(7): 1515–1526

Ferraris, C. F., Stutzman, P. E. and Snyder, K. A. 2006. Sulfate resistance of concrete: a new approach and test, R&D Serial No. 2486, Skokie, IL: Portland Cement Association (PCA).

Gani, M. S.J. 1997. Cement and concrete. 1st ed, 49–169. England: Chapman and Hills. 

Hoff, G. Durability of offshore and marine concrete structures. 2nd international conference(ACI SP-127), Montreal, Canada. Farmington Hills, MI: American Concrete Institute. pp.33–64.

Kaushik, S. K. and Islam, S. 1995. Suitability of seawater for mixing structural concrete exposed to a marine environment.Cement and Concrete Composites, 17(3): 177–185. 

Kumar, S. 2000. Influence of water quality on the strength of plain and blended cement concretes in marine environments. Cement and Concrete Research, 30(3): 345–350. 

Liu, H., Tai, N. and Lee, W. 2002. Effect of seawater on compressive strength of concrete cylinder reinforced by non-adhesive wound hybrid polymer composites. Composites Science and Technology, 62(16): 2131–2141.