Problem 5: (20 points) A blend is composed of 30% Aggregate A and 70% Aggregate

Question

Problem 5: (20 points) A blend is composed of 30% Aggregate A and 70% Aggregate B, as shown in table below, a) Determine the percent passing each sieve of blended aggregate. (Fill in the table, round to 1 decimal place) b) Does this blended aggregate meet the specification? If not, what is your recommendation to meet spec? Determine fineness modulus of blended aggregate. c) 1 1/2 in. 38 in. I Percent Passing No. 4 No. 8No.16 No. 50 I No. 100 No.200 Sieve Size Aggregate A 100100 100 100 70 Aggregate B 100 90 Blend 32 15 70 50 40 10 Specification 100 95-100 70-85 55-70 20-40 0-20 4-8 0-5

Explanation / Answer

The percentage passing for blended aggregate is calculate the excel table below

.%blend of aggregate A = 30% X %Passing --------------- 1

.%blend of aggregate A = 30% X %Passing -----------------2

Bend = 1 + 2

B. The blended aggregate is not meeting specification. Seive 3/8 and No. 16 are not within the specification or design range. we have to make adjustment to aggregate % used. by trial and error. Try different combination percentage of aggregate A and aggregate B.

C. Calculate the cumulative percentage retained in each seiveusing the formula

cumulative % retained = 100 - % passing of the blended aggregate

Now sum of all the cumulative % RETAINED = 391.1

SO Fineness modulus of the blended aggregate is 391.1/100 = 3.911

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---