CE315-101 Final Report Each of you will submit your own final report. Final report will be included in your final score for CE315. Please read through the requirement of the final report. This is NOT like your memo, or group report. The evaluation rubric is attached. Technical Content Your final report should include all the data you measured during the lab this semester: (1) Aggregate: coarse aggregate unit weight, gradation; fine aggregate gradation (2) Portland Cement Concrete: mix design, concrete fabrication, slump, unit weight, and compressive strength This report is designed to present a complete professional document explaining the procedure, outcome, and recommendations of the test or series of tests. This document should be treated as a formal report that will be submitted to a client for project recommendations. Reports must include the following information and will be graded accordingly. 1. General information a. The report should be neat in appearance with sufficient margins and have “Justified” text. b. Be written in third person and be brief but complete. Content is more important than length. c. A stranger unfamiliar with the particular experiment should find the answers to the following questions in the report: Who?, When?, Where?, What or Why?, Theory or Practice?, Using or Testing what?, How?, and Results? d. Page numbers should be used at the bottom of the page and centered. Do not number the Cover Sheet, but do count it in the number of pages. 2. Divisions of the Report: To simplify the report writing, the report will be segregated into divisions. Each division must be included in the report, unless otherwise specified, in the order given below. Allow two to three spaces between the end of one major division and the heading of the next. Only the Table of Contents, Letter of Transmittal, Abstract, first page of the report beginning with Introduction, Appendix Flysheet, and the Appendices should begin on new sheets. The order of the divisions will be as follows: a. Cover Sheet (Page No. i, do not put a page number on the cover sheet) i. Follow the format of the Cover sheet of the attached page (Appendix C) b. Table of Contents (Start a new page) c. d. e. f. g. h. i. List all divisions and subdivisions of the report including the Letter of Transmittal with the corresponding page numbers ii. Word can create this for you (Google “Styles and Table of Contents”) Letter of Transmittal (Start a new page) i. This is a business letter written to the client written in first person ii. Includes a brief summary of the objectives, results, conclusions, and recommendations to properly introduce the report to the reader Abstract (Start a new page) i. The abstract applies to the report as opposed to the test or experiment and should be 100 words or less and concisely state 1. What the problem is and what the author has done 2. How it was done (if that is important) 3. The principal results (numerically, when possible) 4. The significance of the results (important conclusions) ii. The abstract should not include any references, figures, or tables. Introduction (Page no. 1) i. A clear, concise statement should be given of the purpose, significance, and benefits to be derived from the experiment. Literature Survey and Theory i. The basic theory and the fundamental principles on which the investigation rests should be stated precisely so as to prepare for the experimental work which will follow in the rest of the report. All equations used in the report must be either reported from the literature survey or derived in this division. ii. Reference all materials according to the standards of ASCE. Procedural Outline i. Brief description of the procedure ii. List any standard procedures followed and any deviations if applicable iii. A notation of the accuracy of the results iv. A schematic sketch or photo may be included of the equipment used. In addition to images, sufficient explanatory information is necessary to identify all equipment. v. A list is helpful and information such as type, manufacturer, serial number, range and readability (if applicable) Results and Discussion i. This division includes tables, graphs, comments, analysis and discussion of the results obtained or of the operation of the test or experiment. ii. Tables shall consist of only the information pertinent to the purpose of the testing or research and is usually consistent of some or all of the calculated and theoretical values. Each table is numbered consecutively with a title at the top of the table. iii. Graphs should be used to better organize or present data that is calculated or obtained. The scales of the axes should be chosen carefully to present the data in a reasonable fashion. Each axes requires a label and the appropriate unit of scale. Each graph should be considered a figure and is numbered consecutively with other figures (or images listed as figures) with a title at the bottom of the figure. iv. The analysis and discussion of the results are the most important aspects of the report. Be brief but present a complete analysis of the results obtained. Relate results already presented to some authority, if possible. If there are any errors that effect the results or that were evident during the testing, present possible sources and tell how these can be deleted in future testing. Limitations of the apparatus and resulting experimental accuracy should be discussed. i. Conclusions i. Summarize the entire report. ii. Indicate how the results are related to the objectives of the test or experiment. iii. Note that the conclusions apply to the test or experiment, not the report. j. References i. The references used in the preparation of the report shall be listed and formatted according to ASCE. k. Appendix (Start a new page) i. An Appendix Flysheet should start the division with the word Appendices centered in the middle of the sheet. ii. Start a new page for each appendix section (labeled A, B, etc) iii. Appendix material should be any information that is pertinent to further explain a topic discussed in the report, but was not necessary to fully present an idea, theory, or calculation. iv. Further calculations, derivations, images, or background data may be presented in an appendix. University of South Alabama Department of Civil, Coastal, and Environmental Engineering CONSOLIDATION OF DIRT Dave Jones CE315 Section 101 November 13, 2017 CE 315: Civil Engineering Materials Lab Formal Report Evaluation Name: ____________________________________ The report will be evaluated for technical correctness, clarity of explanation, grammar, and spelling. Maximum Points Cover Sheet 2 Table of Contents 2 Letter of Transmittal 5 Abstract 8 Introduction 8 Literature Survey 8 Procedural Outline 7 Results and Discussion 15 Conclusions 10 Citations and References 5 Technical Writing (grammar, paragraph and sentence structure, technical language, etc.) 25 Appendices 5 Subtotal (100 possible) Grading rubric attached and filled out -5 Submitted on USA Online and paper copy -10 Evaluation date Total Score UNIVERSITY OF SOUTH ALABAMA Shenghua Wu, Ph.D., LEED AP September 5, 2017 Department of Civil, Coastal, and Environmental Engineering University of South Alabama Subject: CE 315 Civil Engineering Materials-Lab #1: Specific Gravity, Absorption of Coarse Aggregates, Bulk Unit Weight & Voids in Aggregates Dr. Wu, The report below includes the results of the experiment to determine the Specific Gravity, Absorption, Bulk Unit Weight, and Voids in Coarse Aggregate. The experiment was conducted on August 28, 2017, in the civil engineering lab following the procedures outlined in the book “Materials for Civil and Construction Engineers” for ASTM C17 and ASTM C29. Two experiments were carried out i.e. experiment No. 7 for determining Specific Gravity and absorption of Coarse Aggregates and experiment No. 9 for determining Bulk Unit Weight and Voids in Aggregates. The research team included Ali Alshehri, Shadi Alzahrani, and Cory Judkins. The mass of the empty water tank was first determined which was 0.74 lb and then mixing aggregate and sample which was 8.26 lb. The aggregate was in the water for 24 hours, so this step was not needed in this lab. The specimen was then removed from water and rolled in a large absorbent cloth to remove water. The sample was then weighed which was the SSD and equal 7.98 lb. The sample was placed in the wire basket to measure its weight after shaking the basket just a little bit to ensure all entrapped air has been removed and we got the submerged weight of 4.17 lb. Finally, we put the sample in the oven and its dry weight recorded as 7.12 lb the following day. After finishing this experiment, we determined the bulk Unit Weight. The weight of the pan was determined which was 7.76 lb. Then, the weight of the pan with the sample was 32.62.lb. Since the volume of the sample was provided as 5.32 in3, the value for Unit Weight of Aggregate (M) was then computed. Finally, the void content was determined. The results of the experiment were computed as follows. For Experiment No. 7: Bulk Specific Gravity = A/ (B - C) = 7.12/ (7.98 – 4.18) = 1.87 Where; A = mass of oven-dry sample in air, (g) B = mass 0f saturated surface-dry sample in air, (g) C = mass of saturated sample in water, (g) Bulk Specific Gravity (SSD) = B/ (B – C) = 7.98/ (7.98 - 4.18) = 2.10 Apparent Specific Gravity = A/ (A - C) = 7.12/ (7.12 – 4.18) = 2.422 Absorption, % = [(B – A) / A] * 100 = [(7.98 – 7.12) / 7.12] * 100 = 12.08% For Experiment No. 9: Bulk Unit Weight, M = (G – T)/ V = (32.62 – 7.76)/ 532 = 0.05 lb/in3 or 86.38 lb/ft3 Void content, % VS = [ᵞb/ (Gsb * ᵞb)] * 100 = [86.38/ (1.87 * 62.3)] * 100 = 74.15% % Voids = 100 - % VS = 100 – 74.15 = 25.85% The results designate that the course aggregates utilized had low void content. The accuracy of the results might have been affected by some errors with occurred during experiments. A balance accurate to 0.05% of the sample weight was utilized to ensure high accuracy. It is recommended that several experiments should be carried on and the average value obtained in order to improve the accuracy of the results (Mamlouk et al, 2011). Thank You Ali Alshehri Attachments: Photos of wire basket & water tank used to determine bulk specific gravity & absorption of coarse aggregates. Figure 1: Wire basket & Water tank for experiment No. 7 References Mamlouk, Michael S., and John P. Zaniewski. Materials for Civil and Construction Engineers. 3rd ed. New Jersey: Pearson, 2011. Print. Williams, S. (photograph). New York, NY: Bulk specific gravity measurement, 3 May 1978. UNIVERSITY OF SOUTH ALABAMA DEPARTMENT OF Telephone: (251)460-6174 CIVIL ENGINEERING Facsimile: (251) 461-1400 150 Jaguar Drive, Shelby Hall 3142 http://www.southalabama.edu Mobile, Alabama 36688-0002 Shenghua Wu, Ph.D., LEED AP. University of South Alabama Department of Civil Engineering Subject: CE 315 Civil Engineering Materials -Lab #2: Gradation Analysis, Fine & Coarse Aggregates Dr. Wu, Sieve analysis is a method utilized in the determination of particle size distribution of aggregates in a particular sample by dry sieving. Distribution of particle size is very fundamental because samples are characterized by grain size. This test is used to determine the grading of materials that are to be used as aggregates for concrete. It ensures that particle size distribution complies with applicable requirements and provides the data necessary to control the material of various aggregate products and mixtures. The data may also be useful in developing relationships concerning porosity and packing. The goal of this experiment is to determine the classification of the coarse aggregates by ASTM specifications and also to find the fineness modulus of the fine aggregate. This experiment was carried out at the civil engineering lab at Shelby Hall on Monday September 11. It was done by the group number 9 whose members are Ali Alshehri, Shadi Alzahrani, and Cory Judkins. A sample of a dry aggregate with a mass of 10.04 lb was passed through a series that were arranged progressively by the size of the openings. A pan is placed at the bottom to retain very particles that pass through all the sieves. The mass of the aggregate that is retained on each sieve was recorded to calculate percent retained, percent passing & cumulative percent retained for determination of particle size distribution. ASTM C33 specifications was used to determine the classification of the aggregates by sieving. The mass of aggregates that was retained in sieve 2 in, 1.5 in, 1 in, ¾ in, ½ in and the pan was measured & recorded. The percent retained, percent passing & cumulative percent retained in each sieve was then calculated. The sieve gradation analysis experiment was used for grading the fine and coarse aggregate samples for the use of a concrete mix. Based on the recorded data from dry sieving, the data showed that the fineness modulus of the fine aggregate was 2.79. Also the data for the coarse aggregate was classified from ASTM C33 to have a size number 467 which has a nominal size of 1 ½ inches to No. 4. There was loss of fine aggregates do to grains getting stuck in the sieves and also from transporting the grains to the scale. In addition to aggregates being lost, aggregates were also gained by the collection of particles that were already in the sieves from previous experiments. The collection of other particles caused the team an uncertainty of having .6 grams of excess aggregate in the total. Although there was excess aggregate it did not have a significant effect on the percent retained, thus making the measurement of the fine aggregates gradation adequate for the concrete mix. Thank You Group 9 References Standard test method for sieve analysis of fine and coarse aggregates. (2006). West Conshohocken, PA. Standard test method for sieve analysis of fine and coarse aggregates. (2001). West Conshohocken, PA. Appendix Appendix A: Data collected from sieve analysis Table 1: Coarse Aggregate Dry weight Sieve size (in) 10.06 lb. Weight pan (lb.) 2 1.5 1 ¾ 1/2 Pan 11.94 11.86 12.28 12.86 12.38 11.66 Sieve Size 50 37.5 25 19 12.5 mm mm mm mm mm (2 in) (1 1/2 in) (1 in) (3/4 in) (1/2 in) Loaded weight (lb.) 11.94 11.86 13.50 16.26 15.28 14.20 Aggregate weight (lb.) 0 0 1.22 3.40 2.90 2.54 Total Cumulative mass (lb.) 0 0 1.22 4.62 7.52 10.06 10.06 Amount Percent Retained, lb Retained Percent Passing Here 100 100 88 54 25 Pan Total Table 2: Fine Aggregate Dry Weight Sieve size #4 #8 #16 #30 #50 #100 #200 Pan Total 499.0 g Cumulative mass (g) 3.3 56.0 123.5 263.9 451.6 494.5 498.0 499.6 499.6 0.00 0.00 1.22 3.40 2.90 2.54 10.06 0.00 0.00 12.13 33.80 28.83 25.25 Cumulative Percent Retained Percent Passing 0.00 0.00 12.13 45.92 74.75 100.00 100.00 100.00 87.87 54.08 25.25 0.00 Sieve Size 4.75 mm (No. 4) Percent Passing Here 99 2.36 1.18 mm mm (No. 8) (No. 16) 0.6 mm 0.3 0.15 0.075 Amount Percent Retained, g Retained Cumulative Percent Finesse Percent Passing Modulus Retained 3.3 0.7 0.7 99.3 0.01 89 75 52.7 67.5 10.5 13.5 11.2 24.7 88.8 75.3 0.12 0.37 (No. 30) 47 140.4 28.1 52.8 47.2 0.89 mm mm (No. 50) (No. 100) 10 1 187.7 42.9 37.5 8.6 90.3 98.9 9.7 1.1 1.80 2.79 mm (No. 200) 0 Pan 3.5 1.6 0.7 0.3 99.6 99.9 0.4 0.1 Total 500 Table 3: 0.45 Power Gradation Chart FHWA 0.45 Power Gradation Chart 100 100 90 89 88 100 99 100 88 80 75 73 70 Percent Passing 64 60 54 50 47 47 40 34 30 25 20 19 14 10 50 mm (2 in) 37.5 mm (1 1/2 in) 25 mm (1 in) 19 mm (3/4 in) 12.5 mm (1/2 in) 9.5 mm (3/8 in) 4.75 mm (No. 4) 2 mm (No. 10) 2.36 mm (No. 8) 1.18 mm (No. 16) 01 0.6 mm (No. 30) 0.075 mm (No. 200) 0.15 mm (No. 100) 0.3 mm (No. 50) 0 10 10.00 0.00 0.075 mm (No. 200) 0 0.15 mm (No. 100) 1 Semilog Gradation Chart 99 50 mm (2 in) 89 37.5 mm (1 1/2 in) 25 mm (1 in) 19 mm (3/4 in) 90.00 4.75 mm (No. 4) 2 mm (No. 10) 2.36 mm (No. 8) 50.00 1.18 mm (No. 16) 0.6 mm (No. 30) 100.00 0.3 mm (No. 50) Percent Passing Table 4: Semilog Gradation 100 100 88 80.00 70.00 75 60.00 54 47 40.00 30.00 20.00 25 10 Appendix B: Contributions by each team member Name of Experiment: Gradation Analysis, Fine & Coarse Aggregates Date of experiment: 9/11/2017 Lab day and group number: Monday Group 9 Task Introduction and objective Description of the experiment Results Conclusions References Appendix A Appendix B Cory Judkins (Primary Author) 30 40 60 90 10 50 50 Ali Alshehri Shadi Alzahrani (Secondary Author) 70 60 40 10 90 50 50 CE 315: Civil Engineering Materials Lab Group Report Evaluation Primary Author: _______________________________________ Secondary Author: _____________________________________ Group Number: ____ Lab Name: _____________________________________________________ The report will be evaluated for technical correctness, clarity of explanation, grammar, and spelling. Maximum Points Introduction and objective 10 Description of the experiment 15 Results and Discussion 15 Conclusions 15 Citations and References 5 Technical Writing (grammar, paragraph and sentence structure, technical language, etc.) 30 Subtotal (90 possible) Appendices Section of the report A. Data collected during the experiment 4 B. Sample calculations and summary table or 4 tables of all calculations D. Report of contributions by each team member 2 Subtotal (10 possible) Grading rubric attached and filled out -5 Submitted on USA Online and paper copy -10 Evaluation date Total Punctuality at lab (individual to student) -5 Score 1 UNIVERSITY OF SOUTH ALABAMA DEPARTMENT OF CIVIL, COASTAL AND ENVIRONMENTAL ENGINEERING 150 Jaguar Drive, Shelby Hall 3142 Mobile, Alabama 36688-0002 Telephone: (251) 460-6174 Facsimile: (251) 461-1400 http://www.southalabama.edu October 10th, 2017 Shenghua Wu Department of Civil Engineering University of South Alabama Subject: CE 315 CE Materials Laboratory – Lab 6: Concrete Batching and Cylinder Fabrication Dr.Wu, Designing or mixing concrete incorporates a number of steps. This is attributable to the economical, sustainable, durable, and versatility of concrete. Consequently, there is need for precision and accuracy in steps involved in manufacturing cement; this froths from the need for high-quality concrete. A plant that is involved in manufacture of concrete combines ingredients such as air, water, admixtures, aggregate, silica fume, cement, slag, sand, and fly ash. Henceforth, there is a need to mix these ingredients with conformance to mass or volume before mixing them. In this light, this experiment aims to propose a mix design for concrete utilizing ASTM C31. As well, this experiment puts to perspective a strength of 2500 psi out of which the concrete’s strength will be tested for 14 days and 28 days strengths. As well, unit weight, slump, and air content will be carried out. Batching process in earlier days was mainly done using volume. However, specifications follow the process follows mass in comparison to volume. Below are percentages of measures for materials to be used gauging with accuracy. 2 Cement In a case where cement is more than 30% of size capacity, then its measuring correctness should be around 1% of necessary mass. However, in a case where it is less than 30% then the accuracy should be around 4% of necessary quantity. Aggregates Should the measurement exceed 30% of scale capacity, measuring accuracy should follow 1%. In the contrary, the measuring accuracy should be under 3%. Water Water should be measured in its appropriate volumetric quantity usually 1kg= 1 liter. In this case, the accuracy of measurement should be in the range of 1%. Admixtures Chemical admixtures may utilize the recommended accuracy for water. On the other hand, mineral admixtures should follow cement’s. This accuracy measures follow the fact that mineral admixtures may be used partially to replace cement, while, chemical admixtures are mainly in the form of liquid hence their accuracy’s kowtow to water’s. Usually, this process follows stirring or rotation with the objective being coating the surface of aggregate particles with paste from cement, as well as blinding ingredients into a regular mass. Thereafter, the concrete is subjected to processes of compaction and placing which are undertaken simultaneously. These processes are important in ensuring durability, impermeability, and strength are achieved in the structure of concrete. This lab was conducted by the use of preliminary calculations found from previous data for the properties of coarse and fine aggregates. The team began by collecting the required amount of material and separating them into different buckets. Once all of the materials were collected they were transported near the mixer. The team checked the mixer to make sure that it was clean and ready for use. After the inspection the mixer was turned on and shut off after a few revolutions. Then approximately 1/3 of the volume of water was added to the mixer, and the mixer was turned on again for a few revolutions. When the mixer was stopped the powder like cement along with the aggregates and remaining water were added to the mixer, and the mixer was powered back on. The team let the mixer run for a few minutes to ensure that all of the materials were fully mixed. 3 During the mixing process the team gathered the required apparatus such as molding cone, scoop, measuring device, base, and tamping rod to perform a slump test. The slump test was performed by compacting the freshly mixed concrete into the cone and measuring the vertical displacement of the original height of the concrete to the displaced position of the top of the concrete shown in figure 2. Also a test was performed to measure the unit weight and air content of the concrete. After the tests were performed the team added the concrete back to the mixer and ran it to mix the concrete again. When the concrete was freshly mixed it was scooped, compacted by rodding, and filled into eight cylinders to make samples. The samples were placed in the lab to cure. Once all of the procedures were performed the team carefully cleaned out the mixer with regards to the surrounding environmental area. The team had to return to the lab the following day to strip the samples and place the concrete into a curing tank for 14 to 28 days. Based on calculations as shown in Appendix B, the tables following-up are of overall results, mix design, and batch weight. Table 1: Results Air 5% Slump 3.16 in Unit weight of concrete 109 lb/ft3 Table 2: Mix Design Coarse Aggregate 1745.27 lb/cy Fine Aggregate 1133.89 lb/cy Water 396.02 lb/cy Cement 540 lb/cy Water – Cement ratio 0.65 lb/cy Air 2% Table 3: Batch Weight Coarse Aggregate 39.11 lb Fine Aggregate 25.41 lb 4 Water 8.87 lb Cement 12.10 lb Results highlighted in table 1 were obtained through C143, C231, and C138 ASTM standards. These were the results for air content, unit weight, and slump of the concrete. Given that this concrete mix design was based on 2500 psi compressive strength and a 3 inch slump, the slump obtained was higher than the design. However, after 14 and 28 days, the fabricated concrete will be tested to test its performance under a load equal or greater than 2500 psi. 5 References Gaventa, S. (2006). Concrete design. London: Mitchell Beazley in association with Blue Circle. Mamlouk, M. S., & Zaniewski, J. P. (2011). Portland Cement Concrete. In MATERIALS FOR CIVIL AND CONSTRUCTION ENGINEERS (3rd ed., pp. 246-313). New Jersey, NJ: Pearson Education Inc. Mircea, A. (2011). Fabrication technology-related cracking elements. Concrete Solutions 2011. doi:10.1201/b11585-15 of prestressed concrete 6 Appendix A Data collected: Weight of water bucket: 2.21 lb Water + Bucket = 11.10 lb CA Bucket = 2.21 lb CA + Bucket = 29.52 lb FA Bucket = 1.58 lb FA + Bucket = 35.84 lb Cement Bucket = 1.08 lb Cement + Bucket = 14.82 lb Slump = 6.16 in Weight of Concrete + Air Content Bucket = 43.08 lb Air = 5% 7 Appendix B - Aggregate Data: Coarse Aggregate Sp Gr 2.5 𝜆 102.5 lb/cf ABS 2.46 % MC 0.1 % Fine Aggregate Sp Gr 2.62 FM 2.7 ABS 0.55 % MC 0.12 % 𝑙𝑏 Fine Aggregate = (6.93)(2.62) (62.4 𝑐𝑓) = 1132.54 lb/cy W(CA,wet) = 1743.52 lb/cy * (1+0.001) = 1745.27 lb/cy W(FA,wet) = 1132.54 lb/cy * (1+0.0012) = 1133.89 lb/cy W(water,adj) = 350 lb/cy – 1743.52 (0.001 – 0.0246) – 1132.54 lb/cy (0.0012 - 0.0055) = 396.02 lb/cy - Batch weights: 𝜋 Total Volume = 4 (4𝑖𝑛)2 (8𝑖𝑛)(8 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟𝑠)(1.3) = 1045.5 in3 = 0.0224 cy Coarse Aggregate = (1745.27 lb/cy) (0.0224 cy) = 39.11 lb Fine Aggregate = (1133.89 lb/cy) (0.0224 cy) = 25.41 lb Cement = (540 lb/cy) (0.0224 cy) = 12.1 lb Water = (396.02 lb/cy) (0.0224 cy) = 8.87 lb 40.517𝑙𝑏 Unit weight of concrete = 0.372 𝑓𝑡 3 =109 lb/ft3 8 Appendix C: Contributions by each team member Name of Experiment: – Lab 6: Concrete Batching and Cylinder Fabrication Date of experiment: 10/04/2017 Lab day and group number: Monday Group 9 Shadi Alzahrani Task (Primary Author) Ali Alshehri Cory Judkins(Secondary Author) Introduction and objective 90 10 Description of the experiment 10 90 Results 80 20 Conclusions 70 30 References 60 40 Appendix A 50 50 Appendix B 50 50 Appendix figures 90 10 9 CE 315: Civil Engineering Materials Lab Group Report Evaluation Primary Author: _______________________________________ Secondary Author: _____________________________________ Group Number: ____ Lab Name: _____________________________________________________ The report will be evaluated for technical correctness, clarity of explanation, grammar, and spelling. Maximum Points Introduction and objective 10 Description of the experiment 15 Results and Discussion 15 Conclusions 15 Citations and References 5 Technical Writing (grammar, paragraph and sentence structure, technical language, etc.) 30 Score Subtotal (90 possible) Appendices Section of the report A. Data collected during the experiment 4 B. Sample calculations and summary table or tables of all calculations 4 D. Report of contributions by each team member 2 Subtotal (10 possible) Grading rubric attached and filled out -5 Submitted on USA Online and paper copy -10 Evaluation date Punctuality at lab (individual to student) Total -5 10 Appendix: Figures Figure 1 11 Figure 2 12 Figure 3 13 Figure 4 14 Figure 5 REPORT 1 Shenghua Wu, Ph.D., LEED AP University of South Alabama Department of Civil Engineering Mobile, AL 36688 Subject: Lab 4, 14-day and 21-day Concrete Comprehensive Strength Lab Introduction The following lab was conducted to measure the 14 and 21-day comprehensive strength of cylindrical concrete specimens. The 14-day testing was done on October 16th and the 21-day testing was conducted one week later on October 23rd. The concrete specimens have been created two weeks before and been stored in a tub of water at the lab. The compressive test is only applicable to concrete samples with a weight of 800kg/m3 or more. The process is conducted by applying a comprehensive axial load to a cylinder while recording the rate until failure occurs. The comprehensive strength of the tested material is obtained from dividing the maximum load by the specimen’s cross-sectional area. Another type of compressive test can be used to determine the modulus of elasticity and Poisson’s ratio of the specimen. The test measures lateral and longitudinal strains. It also determines stress to strain ratios for any hardened cylindrical concrete. The value of the modulus of elasticity is expected to be less than that obtained under rapid load application. The examination team included Ali Alshehri, Shadi Alzahrani, and Cory Judkins. Description of the Experiment The lab was conducted first by removing three cylinder samples from the curing and a towel used to dry them. The length was determined by taking the average measurement from two locations of each of the specimen. Similarly, the diameter of the concrete specimen was measured using pi tape in two locations. The specimen was placed in a clean compression testing machine that had neoprene caps in their location. During the compression test, the data collection software was running to record the maximum load/stress. Once the sample had broken, the maximum load and type of break was determined and recorded for each REPORT 2 sample. Also, pictures of the breaks were taken for data analysis. After one week, the same process done for another three cylinder samples and the data was saved and downloaded for analysis. Results and Discussion From the observations of the analyzed fractures it was noticed that the 14-day specimens had a bigger fracture. This implies that the compressive strength of the specimen was higher at the 21-day and increases with the curing days. “The results imply that the concrete had achieved sufficient curing more than those on the 14-day test (National Precast Concrete Association, 2013).” “Curing can be defined as the process of regulating extent and rate of moisture loss from a concrete during its hydration (Barger, 2013).” The 14-day specimen in figure 1 is described as a shear fracture whereby it involves diagonal cracking. Figure 2 displays a cone fracture while Ffigure 3 shows a cone and shear fracture. The indicated results included three specimens for the 14-day and 21-day break tests. The coefficient of variation for the 14-day specimen is 4.0278-1 = 0.248 while it is 4.056-1 = 0.246 for the 21-day specimen. Table 1: the measures of diameter. Specimen no. 14-day 21-day 1 4.0278 4.056 2 4.0278 4.056 3 4.0278 4.056 Table 2: Values of the peak load/stress Specimen no. 14-day 21-day 1 56k 54k 2 52k 55k 3 51k 58k There are two main methods through which the modulus of elasticity can be calculated. The first technique involves using the secant modulus as referenced in AC318. In this case, Excel was used to plot the data collected and the best line of fit is obtained. The slope of the line of fit is the secant modulus. The data that is used is clearly selected. The second approach involves evaluating the chord modulus as outlined in the standard ASTM C469. REPORT 3 This can be represented as: 𝐸𝑐ℎ𝑜𝑟𝑑 = 𝑠2 − 𝑠1 𝑝𝑠𝑖 𝑒2 − 0.00005 The obtained modulus of elasticity is then compared to two equations. The equations given from ACI for normally weight concrete is represented as: Etheoretical = 57000 × √𝑓𝑐 ′ psi. The second equation is the theoretical modulus of elasticity. From AC318. In this case, Etheoretical = wc1.5×33× 57000 × √𝑓𝑐 ′ psi. Where is wc is the unit weight. The final step involves determining the Poisson’s ratio. This is done in accordance with the standard ASTM C469. The ratio for this is:𝑣 = ∈t2−∈t1 ∈2−∈1 (This value is dimensionless) Conclusions After conducting the compression test on the 14 and 21-day samples, results show that the 21-day cylinders had a higher compressive strength. Another compressive test using a compressometer can determine values such as lateral and longitudinal strains. The strains are used for finding the modulus of elasticity and poisons ratio. Due to deficiency the values were not found for the samples. The fractures that described the breaks from the specimens were cone, shear, and both cone and shear. Majority of the samples had a cone fracture. REPORT 4 References Barger, E. (2013, October 28). Oliver Tsai. Retrieved October 30, 2017, from http://precast.org/2013/10/28-day-myth/ National Precast Concrete Association. (2013). National Precast Concrete Association. Retrieved October 30, 2017, from http://precast.org/why-precast/ REPORT Appendices Appendix A: Data that has been collected from the experiment Figure 1: 14-day specimen 1 break Figure 2: 21-day specimen 1 break Figure 3: 21-day specimen 2 break 5
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