Question How does the temperature and environment affect the strength of concrete?

Why...!? I am doing this project because my dad works for a concrete precast company so I was interested in how it cures in different environments. I was also interested in finding out how some of the machines and such work!

Hypothesis My hypothesis is that the concrete cured outside the water will be stronger because the water will slow down the curing process.

Independent and dependent variables The independent variable in my experiment is the environment in which its cured. The dependent variable is the concretes strength.

Controlled variables The quality of the materials put into the concrete to make it. The size and weight of the concrete The period of time curing. The testing process of concrete strengths. The process of making concrete cylinders.

Standard of comparison My control group is the concrete being cured in water in the curing tanks.

Materials Thermometer Concrete crushing machine. Vibrating machine. Cement, flyash, sand, gravel, and water. Concrete mixer. Will barrow. Pressing tool. Rubber mallet. Cylinder stripping tool. Cylinder molds. Curling tank

Procedures  Get will barrow. Wet it and dump out the excess water.  Get concrete sample and take the temperature of it.  Go to viberater table and fill cylinder molds in 1/3 rd’s using pressing tool every third.  After the molds are full, turn vibrating table to low and smooth and flatten the top of the cylinder.  Put lid on the cylinder mold and carefully move them to curing area.

Procedures (continued) After concrete has cured over night, strip the cylinders using a rubber mallet and a cylinder stripping tool. Then take cylinders to curing tank and to the pouring area. Wait 23 days then crush cylinders with concrete crushing machine. (Record data) Compare data (results) to see which cylinder broke at the highest strength.

Qualitative observations Observations I made in the beginning of my experiment are, the cylinders are pretty smooth but have lots of tiny holes and bumps. Observations I made in the middle of my experiment are, when the cylinders are either in the curing tank or air drying they seem to be heavy but I to me the ones curing in the curing tank were a lot heavier then the other cylinders. Observations I made in the end of my experiment are, the pieces that were broken were very rough and rocky. I also noticed that when the cylinder is broken it breaks in an X shape or if it didn’t it didn’t break right.

Paige's Concrete Crushing Strengths Paige Young Dry Cured Cylinder 1 Dry Cured Cylinder 2 Dry Cured Cylinder 1 & 2 Water Cured Cylinder 1 P.S.I

Analysis The first dry cured concrete cylinder broke at 4810 pounds. The second dry cured cylinder broke at 5210 pounds, leaving a 5010 pound average. The water cured concrete cylinder broke at 7320 pounds. The water cured cylinder having a 2000 pound lead. The breaking date of the cylinders was October twenty-fifth, two thousand eight. The cylinder’s age was 23 days old.

Experimental errors Possible errors I may have made while doing my experiment are not putting the same amounts of sand, concrete, flyash, gravel, and water into each concrete cylinder. Another error would be not making the cylinders completely flat on the top. Not consistent consolidation of the concrete. Breaking the cylinders at different speeds. Not handling the cylinders carefully enough. The results of these problems on my data would change it because the cylinders wouldn’t have been built right and so that could have caused different redults in the crushing machine!

Conclusion I would have to reject my hypothesis because I thought the concrete cylinders were going to cure better outside of water because I thought the water would slow the curing process and decrease the strength. The concrete compressive strength for water curing was 7320 compared to dry cured at 4810 and The cylinders curing in the water (the curing tank) held stronger strengths compared to the dry cured (room temperature) making my hypothesis totally opposite. I think the results came out like this because the water curing process has the water perfectly set for a better stronger cylinder. On the other hand a reason for the dry cured cylinders being weaker to me is because you can’t control the room temperature as much as you can the water so the certain temperature makes team stronger.

Recommendations for further experimentation! If I was to carry on this experiment I would need a better controlled environment to do my testing such as for curing the cylinders in water and out. I would need a basic room temperature that I could control to let the dried cylinders be correctly done. I would also need more trials to get better results and a better outcome in the end on what is better and what type of things work better. I would need better equipment to work with, and more training in making stuff and knowing more on how things work so I understand and know what people and things are.

~Concrete cylinders~

~Crushing machine~

~Crushed concrete cylinder~

~Digital scale~

~Curing tank~

Breaking cylinders

Freshly made cylinder

Cylinder ready for curing!

Making a concrete cylinder!

Perfect cylinder break when showing as a cone!