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CE Materials Lab 2 Title Page

CE Materials Lab 2 Title Page - Laboratory 2 Concrete...

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Laboratory 2: Concrete Testing Civil Engineering Materials CRN: 40647 Date Performed: 10/24/2011 Date Submitted: 11/07/2011 Lab Group 3: Daniel Kirkaldy Miken Shah Jonathan Sparacio Brandon Taylor Jacob Taylor Nicholas Vaspoli Introduction: The objectives of this lab were: 1) Design and create a concrete mixture based on the following conditions: a. Greater than 3000 psi compressive strength b. 3 inch slump c. Exposed to brackish water d. Negligible sulfate exposure e. Moderate freeze-thaw exposure f. Air entrained to 5% of total volume
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2) Mold concrete cylinders and determine the compressive strength for each 3) Mold a concrete beam and determine its compressive and flexural strength Theoretical Information/Literature: Workability Workability is a parameter that measures how easily freshly mixed concrete can be placed and compacted while in the field. It’s a important parameter that is dependent on the amount water within the water to cement ratio and is measured using a slump test. The amount of slump during the test indicates the workability of the cement. Having a higher amount of water in the water cement ratio increases the workability of the cement but also decreases the strength of the concrete. This is due to the excess water occupying more space or volume within the cement mix. When the excess water evaporates it leaves voids within the cement. Having a lower amount of water in the water cement ratio will lower the workability and the amount of voids formed, this increases ultimate strength of the cement. To maintain the ultimate strength and workability of concrete water reducers can be added. Water reducers can neutralize the net static charges that normally build up causing an attractive force between cement particles. Water reducers can break this attractive force between the particles by changing the charge of the particles. With water reducers added the cement particles will repel each other instead of attracting one another (Mamlouk and Zaniewski, 2011). This increases the mobility of cement particles which increases workability. Water reducers allows for less water to be added which forms less voids and maintains the strength of the cement. Water reducers come in different strengths like conventional, mid-range, and high-range that can be used based on how workable you want the concrete to be (Mamlouk and Zaniewski, 2011). Unit Weight Of Freshly Mixed Concrete Measuring unit weight of freshly mixed concrete is important because it allows you to determine the yield, cement content, and air content (Mamlouk and Zaniewski, 2011). The yield is the amount of concrete made from the unknown amount of material used. By measuring the unit weight of concrete you can calculate the volume of the concrete produced. Determining unit weight allows you to compare the actual amount of concrete and yield to the calculated concrete and yields. This allows you to determine if the concrete is being properly mixed. The unit weight also allows you to find the amount of voids or air content within the concrete. By measuring the
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