FinalConcrete.doc

CONCRETEA MATERIAL FOR THE NEW STONE AGEA MAST ModuleMaterials Science and Technology1995Acknowledgments:The authors would like to thank the following people for their advice and support in the development of this module:Dr. Jennifer LewisDirector of the Materials Science WorkshopDr. James AdamsAssistant DirectorDr. Francis YoungDepartment of Materials Science and EngineeringUniversity of Illinois at Urbana-Champaign, Urbana, ILDr. David LangeDepartment of Civil EngineeringUniversity of Illinois at Urbana-Champaign, Urbana, ILAuthors: Beth ChamberlainTuscola HS., Tuscola, ILNewell ChieslUniversity of Illinois at Urbana-Champaign, Urbana, IL Jerald DayTurkey Run HS., Marshall, IN Lesa DowdBishop Noil Institute, Hammond, IN Betty OverockerAntioch HS., Antioch, IL Denise PapeHarlem HS., Machesney Park, IL Marcia PetrusDanville HS., Danville, IL Mary SwansonUniversity of Illinois at Urbana-Champaign, Urbana, IL John TolesSycamore HS., Sycamore, IL ForewordThis is one in a series of MAST modules developed and revised during the Materials Technology Workshop held at the University of Illinois at Urbana-Champaign during 1993-95.A combination of university professors, high school science teachers, and undergraduate students, came together to create and revise this module over a three year period.This module is to be used as a curriculum aide by high school science teachers who would like to introduce their students to concepts of Materials Science and Technology. Teachers are urged to use one, some, or all of the MAST modules. Some teachers may wish to implement this module in its entirety as a subject unit in a course. Others may wish to utilize only part of the module, perhaps a laboratory experiment. We encourage teachers to use these materials in their classrooms and to contact the workshop with any assessments, comments, or suggestions they may have. Financial support for the Materials Technology Workshop was provided by the National Science Foundation (NSF) Education and Human Resource Directorate (Grant #ESI 92-53386), the NSF Center for Advanced Cement Based Materials, the Dow Chemical Foundation, the Materials Research Society, the Iron and Steel Society, and the Peoria Chapter of the American Society for Metals. The University of Illinois at Urbana-Champaign Department of Materials Science and Engineering and the College of Engineering and the College of Engineering Office of Extramural Education provided organizational support.Table of ContentsAcknowledgments.iiForeword.iiiIntroduction.1A Short Story: A Hard Lesson to Learn.2What is Concrete?.3The History of Concrete: Pictorial Timeline.9The History of Concrete: Textual Timeline.11Scientific Principles.15References.25Resources.26Master Materials and Equipment Grid.27Demonstrations1: Making a Silt Test.292: Conducting an Organic Matter Test.303: Effect of Aggregate on Workability of Concrete.314: It's Heating Up.325: pH of Cement.33Laboratory ActivitiesThe Basic Mix.34Lab 1: What's the Matter?.36Lab 2: How Dense Is It?.40Lab 3: Hot and Cold pHun!.44Lab 4: The Fleet Afloat!.49Lab 5: Stress and Strain!.55Lab 6: Make and Take!.63Assessments.66Glossary.74IntroductionModule Objective:Students will learn about cement hydration, material properties, and making concrete.Key Concepts: Importance and widespread uses of concrete. Component materials used to make concrete. Macroscopic and microscopic structure of concrete. Role of water in the preparation of a concrete mixture. Role of water in the hardening of concrete. Effective ratios of component materials in various concrete structures. Effect of porosity and aggregates on the strength of concrete. Building and testing various concrete structures. Derivation of an optimum ratio of component materials for different concrete applications. Chemical reactions which take place when concrete is mixed. Prerequisites: It is assumed that students will have studied the following concepts prior to beginning this module: Calculation of ratios and using fractions Using a laboratory balance to measure mass Using a graduated cylinder to measure volume Making and interpreting graphs Placement of Module in Current Curriculum: The material covered in the concrete module may be adapted for use in classes of general science, chemistry, and physics. The basic concepts which may be taught or enhanced by using this module include: Matter classification Density Compression and tension Hydration Heats of reaction pHThe materials and activities in this module are intended to introduce the student to the topic of concrete. Further lecture, audiovisual, reading, speakers, field trips, worksheets, and evaluation instruments could be used to support and expand upon the materials provided. An excellent activity would involve a field trip to a local ready-mix concrete plant or a cement manufacturing plant. This would give students the opportunity to not only see how concrete is produced but also the many applications of concrete. There is a list of professional concrete organizations in the Resources section which can provide you with further information.A Hard Lesson to LearnA Short StoryBy Betty Overocker"Hey you! Let's go for a walk." said a gruff voice behind me as I sat on a concrete park bench. Without question, I stood up and walked along the concrete sidewalk in the direction the dark suited man pointed to. The heat of the day was intense as it radiated off the concrete building that lined the concrete street we were walking beside. I paused momentarily to lean against a concrete lamp post and concentrate my slurry of thoughts into a more rigid mass. The men in dark suits continued to move me along this set journey.At a large concrete archway, the men told me to enter. The entrance was very steep, and contained two concrete statues of vicious looking dogs guarding the way. The door opened into a large room. The walls were made of concrete blocks arranged in an off-set pattern. My mind tried to trace an escape route in the mortar trails between the bricks, but I kept running into dead ends much like the situation I was in, there were no concrete answers.The room was arranged in a court hall formation consisting of massive poured concrete chairs and benches. A man of questionable character sat in the front of the room, in the largest of the concrete thrones. The men in dark suits motioned for me to approach the front. Being tired from the long walk, I leaned against the concrete pillars that outlined the path that I least wanted to travel.I approached the domineering godfather. He told me to place my legs into a cylindrical container that came up to my knees. The two goons that had been watching me headed to a concrete box nearby. One of the goons carried a bag of pre-mix concrete. The other, a container of water. As they began to mix these ingredients, I began to realize what was about to occur. I broke the code of silence and asked the godfather if I could have one last request. He nodded. I surveyed the scene. Knowing that this long look of the tall concrete skyscrapers may be one of my last, I asked for a large soda and a large cotton candy. Not bad, I thought for a diabetic on his supposed last binge.As my last requests arrived, the goon's transferred the contents of the concrete mix into the bucket. I could feel the weight of the wet mass entering my shoes. I squirmed just as the deliverer was handing me the food. In the shuffle, the large soda slipped out of his hand and spilled into the bucket in which I was standing. The cotton candy also was lost to the mess on my feet. The dom thought nothing of the new additives in the mixture. I, on the other hand, was pleased that my plan had worked.What followed was the usual take-and-get-rid-of-the-guy routine. The goons were not too bright on the ways of concrete. They just followed directions. As for me, the training I received in a high school module on concrete had taught me all about the effects of admixtures on the curing processes of concrete. The sugar in the candy and the soda would prevent the concrete from setting. As the assistants carried me and my "hardened" boots to the water's edge, I hoped that all that modular information was accurate because my life now depended on it. The buckets and I were set on a dolly for ease of movement. The dolly was rolled to the edge of the drop off and I was released into the water.Due to the retardation effect of sugar on the setting of concrete, I managed to wiggle my legs out of the fresh concrete anchor and rise to the surface. No one was in sight and I decided to learn more about other industrial materials so I could save my life again some other time.What is Concrete?Brain Storming Activity 1: Concrete Survey1. When was concrete first made?9000 BC 500 BC 100 AD 1756 18242. Circle the possible components of concrete.water cement gravel sand air steel rods3. What is the purpose of cement in concrete?4. What role does water play in producing concrete?5. Why does concrete harden?6. Why does concrete set (harden) slowly?7. How can you make concrete set: faster? slower?8. Is concrete stronger in compression, tension, or the same in either?9. How strong can concrete or cement be (in pounds per square inch (psi)?50,000 20,000 5000 200010. How long can concrete last (in years)?50,000 5000 500 50scores:8-10 materials science major; 5-7 concrete contractor; 2-4 concrete laborer; 0-1 home ownerConcrete Survey (Key)1. When was concrete first made?9000 BC 500 BC 100 AD 1756 18242. Circle the possible components of concrete. water cement gravel sand air3. What is the purpose of cement in concrete?It acts as a primary binder to join the aggregate into a solid mass.4. What role does water play in producing concrete?Water is required for the cement to hydrate and solidify.5. Why does concrete harden?The chemical process called cement hydration produces crystals that interlock and bind together.6. Why does concrete set (harden) slowly?It takes time for the hydrated cement crystals to form7. How can you make concrete set:faster? add calcium chloride or "accelerator"slower? add sugar or "set retarder"8. Is concrete stronger in compression, tension, or the same in either?It is stronger in compression. 9. How strong can concrete or cement be (in pounds per square inch (psi)?50,000 20,000 5000 200010. How long can concrete last (in years)?50,000 5000 500 50scores:8-10 materials science major; 5-7 concrete contractor; 2-4 concrete laborer; 0-1 home owner(Note:Correct answers are given in bold.)Concrete-An artificial stone-like material used for various structural purposes. It is made bymixing cement and various aggregates, such as sand, pebbles, gravel, shale, etc., with water and allowing the mixture to harden by hydration.Here are just a few facts to help convince you that the topic of concrete deserves to become a part of your science curriculum: Concrete is everywhere! Roads, sidewalks, houses, bridges, skyscrapers, pipes, dams, canals, missile silos, and nuclear waste containment. There are even concrete canoes and Frisbee competitions. It is strong, inexpensive, plentiful, and easy to make. But more importantly, its versatile. It can be molded to just about any shape. Concrete is friendly to the environment. Its virtually all natural. Its recyclable. It is the most frequently used material in construction. Slightly more than a ton of concrete is produced every year for each person on the planet, approximately 6 billion tons per year. By weight, one-half to two-thirds of our infrastructures are made of concrete such as: roads, bridges, buildings, airports, sewers, canals, dams, and subways. Approximately 60% of our concrete highways need repair and 40% of our concrete highway bridges are structurally deficient or functionally obsolete. Large cities lose up to 30% of their daily water supply due to leaks in concrete water pipes. It has been estimated that the necessary repairs and improvements to our infrastructures will cost $3.3 trillion over a nineteen-year period. $1 trillion of that is needed for repairing the nations concrete. Cement has been around for at least 12 million years and has played an important role in history.Brainsto