CE 3700 Labs 3.4 and 5 Report

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Louisiana State University *

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Apr 3, 2024

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CE 3700 Engineering Materials Laboratory “Compressive Strength on Cement Mortar Cubes” (Lab 3) “Compressive Strength on Cylinders and Slump Test” (Lab 4) & “Compressive Strength Testing on Mortar Cubes and Concrete Cylinders” (Lab 5) Performed By: Group 1 Section 2 Submitted by: Danielle Brigoli Date Performed: Date Submitted: February 8 th , 22 nd , and 29 th March 5th Department of Civil and Environmental Engineering Louisiana State University Spring 2024
Introduction & Purpose: Compressive Strength on Cement Mortar Cubes: This experiment aims to determine the compressive strength of 3 different Cement Mortar Cubes at three other plastic conditions. Before experimenting, students must follow the test procedure ASTM C-1099 and these conditions to determine which water quantity allows for the greatest compressive strength. Each group must perform on the assigned water ratio of 1kg of water to 4kg of cement and use the ASTM C-1099 procedure to determine how much any of the materials could be hard or soft enough to measure their compressive stress (psi). The compressive length will be determined using the Forney Compression Tester 14-21 days after curing to see how much load the material weighs (lbs). In most cases, this experiment is used for everyday life because of the specific strength of concrete, and the contractor would provide the cheapest way to use the precise cement-to-water ratio. Compressive Strength for Slump of Concrete Cement: The slump test for Portland cement aims to measure the material's workability. It is vital because normal concrete slumps are 2-4 inches. The significance of this experiment is making sure the slump value is acceptable; if the slump is 4-6 inches, the material would have a high slump value, which is not optimum. The use of this experiment is to determine the proper plastic mixture for the given design criteria. Highway pavements use plastic concrete at a slump test of 1 inch, so this experiment is used daily in concrete design for roads and buildings. Compressive Strength on Mortar Cubes and Cylindrical Concrete Specimens: In this procedure, once the strength of the mortar cube is known, students must be able to measure the optimum cement-to-water ratio for ideal compressive strength by allowing specimens to cure for seven days. Then, it is tested for failure using a Forney Compression tester. The significance of this procedure is to know the strength of a material when selecting concrete for a specific purpose and in concrete design while it is to help determine concrete’s portioning and mixing. Significance and Use: Sypnosis in all labs as described: In this experiment, students must determine the compressive strength of 3 cement mortar cubes and three cylindrical mixtures. The results will differ depending on the group's water ratio and the cement’s stress and load. At the end of the experiment, students must calculate the weight and determine that the compressive strength is strong enough, or it could fail.
Apparatus/ Equipment: Compressive Strength on Cement Mortar Cubes: Weights and Weighing Devices Glass Graduates Specimen Molds (2 in. Cube) Mixer, Bowl, and Paddle Flow Table and Flow Mold Tamper Trowel Moist Cabinet or Room Testing Machine Compressive Strength for Slump of Concrete Cement: Cylinder Molds Tampering Rod Mallets Small Tools Sampling and Mixing Pan Testing Machine Compressive Strength on Mortar Cubes and Cylindrical Concrete Specimens: Mold Tamping Rod Measuring Device Scoop Test Materials: Portland Cement Concrete, Water Cement Ratio
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These test materials are used to perform this lab for the Portland cement, composed of several different materials such as limestone, silica, alumina, iron oxide, and gypsum. The sample weight differs slightly from ASTM C 109, C 109M, which requires 1375 g of sand, 245 g of water, and 500 g of cement. In this experiment, there are 907.2 g of sand and cement and 453.6 g of water. In conclusion, the water-cement ratio of 0.50. Compressive Strength of Cylindrical Concrete Specimens and Slump Test The cement used in this lab is type 1 Portland Cement, with ASTM C192, ASTM C143, and ASTM C39 standards. The group was assigned a mix for a water-cement ratio of 0.38 and a target compressive strength of 2500 psi. Each component of the mixture weighed 4.22 lb of cement, 3.32 lb of water, 18.54 lb for the Coarse Aggregate, and 12.74 lb of fine aggregate. The total material weight will reach up to 38.82 lb. Test Procedure: Portland Cement Concrete, Water Cement Ratio (3 Mortar Cubes) (Lab 4): The procedure that the Portland Cement Concrete experiment required was done in compliance with ASTM-150, C-109, and C-39. Each of the three groups was given a different water/cement ratio, with our group testing a w/c ratio of 50%, which utilized 453.6 grams of water. We mixed half of the predetermined amounts of water, sand, and cement until the mixture was uniform and then mixed the rest of the materials. Once the mixture was uniform, half the material was transferred to a three-cube mold measuring 2 x 2 x 2 inches. The tampering tool was then used to remove any air bubbles from the mold. Then, the material's last half was added and tampered down to eliminate air bubbles (Figure 2). A rubber mallet was used to tap on the sides of the mold to get any other air bubbles out of the mold (Figure 3). A scraper was then applied to the top to smooth the mold, allowing the compressive machine to get the best data for the tests with uniform samples. The samples were then placed into a 100% humidity room to cure. Once curing for seven days was complete, the samples were subjected to the compressive strength test until failure was reached. Figure 1 Figure 2 Figure 3
Compressive Strength of Cylindrical Concrete Specimens and Slump Test (Labs 5 & 6): ASTM C192 did the test procedure, but the molds are set for seven days to cure rather than 28 days, as suggested in the ASTM standards. To begin, the materials of water, Portland cement, fine aggregate, and coarse aggregate were weighed and placed into separate containers (Figure 4 & 5). The materials were mixed to form a uniform mixture using the hands of the person experimenting. The mixed material was then placed into a 12-inch cone mold and filled 1/3 at a time (Figure 6). After serving a third, it was tampered with 25 times to remove air bubbles. This was repeated three times till the metal cone was full. The mold was then tapped on its sides to remove any excess air on the sides. The mold was put onto the ground according to ATSM standards and removed. The slump was then measured by placing the mold next to the concrete sample and the distance measured between the height difference. The slump for our group was 5.5 inches (Figure 7). The material was then removed from the floor and put into the container. A third of the material was poured into the three-cylinder molds and then tampered with to remove excess air bubbles. This was repeated till the molds were full. A rubber mallet was then used to hit the sides of the molds to help release the last air bubbles and evenly disperse the mixture. Due to low vibration, a table was used to remove the previous air bubbles for the water-cement ratio. The straight edge was then used to smooth the top of the cylinder molds (Figure 8). After the specimen was covered and placed in the humid room, it was allowed to cure for seven days. After seven days, the molds were removed, and sample dimensions and weight were recorded. These samples were then placed into the specimen machine and had a load applied till they reached failure. Figure 4 Figure 5 Figure 6
Figure 7 Slump Test Figure 8 Analysis of Results: Portland Cement Concrete, Water Cement Ratio (3 Mortar Cubes) (Lab 4) The material's strength is determined by dividing the total force by the area of the perpendicular cross-section. With the lack of aggregate in the mixture, the compound made was a mortar. The water-cement ratio for group 1 was 0.5, while the other groups used a 0.4 and 0.3 water-cement ratio. The main goal was to determine the average rate of failure when a load was applied to each sample. It was also to see how the rates of failures for each group compared with the water or cement ratio. TABLE 1: Group 1 Individual Cube Results Sample Area (In^2) Load At Failure (lbs) Compressive Strength (psi) 1 4 37658 9414.5 2 4 37254 9313.5 3 4 15663 3915.75 TABLE 2: Average Cube Strengths of All Groups Group W/C Ratio Sand (g) Cement (g) Water (g) Average Load At Failure (lbs) Average Compressive Strength (psi) 1 0.3 907.2 907.2 272.2 37456 9364 2 0.4 907.2 907.2 362.9 28852 7213 3 0.5 907.2 907.2 453.6 25347 6336.75
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This graph represents the average load failure of all three group samples after the compressive strength test was performed, which was based on the calculations from 28 days to cure: as shown in the graph, the larger the w/c ratio, the weaker the concrete sample. Graph 1: This chart describes the relationship between the average compressive strength of the mortal cubes tested and water-cement ratios in all three groups. Compressive Strength of Cylindrical Concrete Specimens and Slump Test (Labs 5 & 6 ): Note that the cross-sectional area of cylinders is 12.566 inches^2. During the slump test, the mixture had a 3-inch displacement center. This places the concrete into the medium workability category. Tables 3 and 4 show that lower water-cement ratios produce more robust cylinders. The slump test results in group 1 are about 5 inches. After removing the triangular dome, it turns out that the measurement for the slump test comes out to be 5.5 inches (See figure 7). TABLE 3: Group 1 Individual Cylinder Results (0.67 W/C Ratio) Sample Load At Failure (lbs) Compressive Strength (psi) 1 26164 2082.13 2 23294 1853.73 3 25020 1991.09 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Compressive Strength and W/C Ratio on the Cement Concrete (3 Mortal Cubes) W/C Ratio Compressive Strength (psi)
TABLE 4: Average Cylinder Strength for All Three Groups Group Water/Cement Ratio Average Load At Failure (lbs) Average Compressive Strength (psi) 1 0.67 24826 1975.65 2 0.51 41360 3291.42 3 0.38 56539 4499.36 Graph 2: This graph represents the compressive strength of the W/C Ratio for Cylinders. Findings and conclusion: Portland Cement Concrete, Water Cement Ratio (3 Mortar Cubes) (Lab 4): In Table 2, the three mortal cubes show more strength when they have a lower water/cement ratio. Though certain mixtures may be more robust, they are not always the most cost-effective. The cube did not break into the shape of an hourglass, likely because of incomplete blending and mixing of the water/cement that is given measurements. The cubes also may not have been tampered with. The picture on figure 9 shows the cube before the compression. 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Compressive Strength and W/C Ratio for Cylinders
Figure 9 Compressive Strength of Cylindrical Concrete Specimens and Slump Test (Labs 5 & 6 ): The test results from the procedure show that smaller W/C ratios result in cylinders that can withstand more stress. However, there must be some threshold where insufficient water results in weaker concrete that breaks easily. Again, using more water, if possible, can be more effective. In this lab, finding a cylinder that can resist 2600 pounds of stress would require more water and less material than the most robust concrete in group three. Using the formula from the chart, the ideal W/C ratio would be 0.65, which is closer to the group 1s ratio than the other groups. The type 3 failures align with the amount of time for the concrete to cure. In figures 10 and 11 shows the cylinder’s before and after compression. Figure 11 shows the cracks diagonal to the parallel like pattern in a 7 day compressive strength.
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Figure 10. Before compression Figure 11. After compression