What is concrete? Forms when you combine: – Cement – Aggregate Sand Gravel – Water http://www.nemati.com/papers/ccr1.htm
What is cement? Binds other materials together Portland Cement is commonly used in construction – Limestone – Clay Cement CompoundWeight PercentageChemical Formula Tricalcium silicate50 %Ca 3 SiO 5 or 3CaO. SiO 2 Dicalcium silicate25 %Ca 2 SiO 4 or 2CaO. SiO 2 Tricalcium aluminate10 %Ca 3 Al 2 O 6 or 3CaO. Al 2 O 3 Tetracalcium aluminoferrite 10 % Ca 4 Al 2 Fe 2 O 10 or 4CaO. Al 2 O 3. Fe 2 O 3 Gypsum5 %CaSO 4. 2H 2 O http://matse1.matse.illinois.edu/concrete/prin.html
What happens when you mix cement and water? Hydration! Tricalcium silicate + Water Calcium silicate hydrate + Calcium hydroxide + heat 2 Ca 3 SiO 5 + 7 H 2 O 3 CaO. 2SiO 2. 4H 2 O + 3 Ca(OH) 2 + 173.6kJ
Quikrete Contains: – Binding agent (cement!) – Sand – Gravel We will be adding fibers to the mix: – Paper strips – Twine – Thick yarn
Concrete Lab 1 Intro Experimental Goal: The purpose of this experiment is to examine how fibers in concrete affect its flexural strength. Hypothesis: Will concrete that contains twine or yarn or paper fibers be stronger, weaker, or the same as concrete that does not have additional components? Justify your answer with reasoning! Safety – goggles and gloves!
Concrete Lab 1 Procedure You will be making two concrete bricks today, one containing fibers and the other without one. 1.Label two molds with your names and clearly mark which will contain the fibers. 2. Mix 2 Dixie cups quikrete and 1 Dixie cup water in a solo cup, then add in 2 more cups of quikrete and mix. 3. Scrape the mixture into the “without fibers” mold. 4. Fill a Dixie cup with yarn, string or paper fibers (your “mix-in”) 5. Repeat step 3, except add in your mix-in with the first 2 cups of quikrete. 6. Scrape it into the “with fibers” mold. 7.Smooth the tops of your bricks with the plastic knives.