Solving Percentages in Mix Design for Asphalt Plants | Help with Math Problems

[dspicher]

Hi, I am new to forums in general, but here goes. i have found myself stumped over a basic math problem with a new operating system on an asphalt plant I operate. I am sure there is a simple formula to solve this.

the mix design or "recipe" calls for percentages of stone and sand totaling 100 percent. so the design reads #8 gravel 20%, #8 limestone 18%, sand 5%, #12 limestone 18%, fines at 2%, recycled asphalt at 35% and recycled shingles at 2%.

i used to just type in the percentages on the mix computer and run the mix but on the new system my recycled products must equal 100 percent. so how do i express 37% of the recycle to equal 100%. so in my ignorance I used 95% recycled asphalt and 5% recycled shingles. (i came to this by multiplying 2.7 x 35 = 94.5 round up for a whole number 95%) this came about with trial. 2.5 no, 2.6 hmm not quite...

i hope this makes sense. try not to tear me apart because of my ignorance, lol. I have many skills but math seems to have slipped away as i grow older. its amazing what you lose if you become complacent. thanks

 

[Prove It]

Hi, I am new to forums in general, but here goes. i have found myself stumped over a basic math problem with a new operating system on an asphalt plant I operate. I am sure there is a simple formula to solve this.

the mix design or "recipe" calls for percentages of stone and sand totaling 100 percent. so the design reads #8 gravel 20%, #8 limestone 18%, sand 5%, #12 limestone 18%, fines at 2%, recycled asphalt at 35% and recycled shingles at 2%.

i used to just type in the percentages on the mix computer and run the mix but on the new system my recycled products must equal 100 percent. so how do i express 37% of the recycle to equal 100%. so in my ignorance I used 95% recycled asphalt and 5% recycled shingles. (i came to this by multiplying 2.7 x 35 = 94.5 round up for a whole number 95%) this came about with trial. 2.5 no, 2.6 hmm not quite...

i hope this makes sense. try not to tear me apart because of my ignorance, lol. I have many skills but math seems to have slipped away as i grow older. its amazing what you lose if you become complacent. thanks

Hi dspicher, welcome to MHB.

I understand that you have certain ingredients for your mix, which total up to 100%. That's fine.

But then I'm not sure what it is you are asking. Are you saying you have to change your mix so that all of your ingredients are now recycled?

 

[dspicher]

The mix design will remain the same but it will be broken into 2 parts. Recycled material and virgin material. the new computer program needs it entered as 100% recycled and 100% virgin material totals.

So just for example 37% of the total mix is recycle but i have to enter this to total 100%

2% becomes 5% and 35% becomes 95% to make up 100 percent of my recycle feeders.

Then I do the same with the 63% virgin material. The program needs to see 100% total. So i do the same crude "expansion" .

I think this will help explain.

 

[MarkFL]

The mix design will remain the same but it will be broken into 2 parts. Recycled material and virgin material. the new computer program needs it entered as 100% recycled and 100% virgin material totals.

So just for example 37% of the total mix is recycle but i have to enter this to total 100%

2% becomes 5% and 35% becomes 95% to make up 100 percent of my recycle feeders.

Then I do the same with the 63% virgin material. The program needs to see 100% total. So i do the same crude "expansion" .

I think this will help explain.

To scale the numbers up, divide by the portion of the total. For example:

$$\frac{2\%}{.37}=\frac{200}{37}\%\approx5.405405405405405\%$$

$$\frac{35\%}{.37}=\frac{3500}{37}\%\approx94.5945945945946\%$$

 

[dspicher]

Eureka. Thats what i wanted to learn. Thank you very much. I hope I can repay the favor some day.