It has been a while since I did experiment about concrete during my previous YSEP study. Here, in ITB, we rarely have experimental research especially for bachelor student final project. Mostly, we do computational research about some methods in analyzing structure behavior of building. I am kind of missing doing this experimental works although this kind of works consumes times and energy.
Fortunately, one of my college friends is doing her final project about fiber reinforced concrete flexural behavior. She discusses the effect of concrete mixed with silica fume and poly prophelene fiber to flexure characteristic of the concrete. In order to get the result, she has to casts and tests several concrete specimens which are compression test, tensile splitting test, and flexure test. She also has to cast her concrete specimen by her own (but off course with the help of technicians)
After knowing that she is doing such kind of research work, I voluntary help some of her experiment and casting works. Even though it is a tiring work, I just can miss the moment I touch the concrete and do analysis of many parameters regarding the research. At least, I can give my little knowledge about concrete experiment to her so I won’t bother her work.
So, I casted several concrete specimens with her and technicians. Unlike in TokyoTech, all of the experiments done here should be done by the help of technicians. Students are not allowed to use the tools by their own since it could risks the tools. The students could accidentally damage the tools and hinder the research progress of other people. As for this step, I forgot to take pictures of the casting works so let’s go to the next step, the experiment.
As I mentioned before, the experiment works are consisted of compression test, tensile splitting test, and flexure test. The compression test is used to measure the compressive strength of concrete and also can be used to measure the modulus of elasticity of concrete. The tensile splitting test is used to measure the tensile strength of concrete. The flexure test is use to measure the behavior of concrete beam when subjected to flexure loading. The pictures below show the flexure test or four point bending test.
From the above pictures, you can see the arrangement of the experiment. The left picture shows the universal testing machine that will push the beam down so flexure crack will occur as shown in the right picture. During the test, the load – midpoint vertical displacement of the specimen were measured using load cell and linear variable differential transformer (LVDT) as shown in the picture below.
The load & displacement were monitored simultaneously using data logger. It is just like a small computer that saves data in every period we determine before. It is the same logger that I used in TokyoTech but with fewer of channels. The data logger can only saves 10 channels of data while in TokyoTech, it can saves 30 channels of data. Also, here, they print the data; not saving it to the diskette just like what we did in TokyoTech.
The result of this test will be a graph that shows load – mid span displacement (or some people say deflection) as shown in the picture below. It is just an example so it might not be same with the result of this experiment. Note: The graph was taken from a journal titled: “Flexural Behavior of High-Strength Fiber Reinforced Concrete Beams” by Ashour & Wafa.
It is just so memorable to do this kind of experiment again since now I am dealing with computer analysis of a structure. From this experiment, I once again trained my muscle as well as my mind. Although it will be so bored and tiring to do it often, it is quite fun compared to just sit in from of computer for the whole day, actually ^_^
– Special thanks to Titi for allowing me to participate in her experiment.
– Special thanks to Anders and Seiko for encouraging me writing another post in english ^_^