5.6 Define the following terms;

a. Saturated surface- dry condition of aggregates – in this condition the aggregate’s voids are filled with moisture but the main surface area of the aggregate particles is dry.

b. Absorption of aggregates – this is the moisture content in the SSD condition.

c. Free water on aggregates – this is the difference between the actual moisture content of the aggregate and the moisture content in the SSD condition.

d. Referring to Figure5.9, which portion of the water in the aggregate that reacts with the cement in the PCC mix? – c. saturated surface- dry (SSD)

5.7 Three samples of fine aggregate have the following properties:

Sample

Measure A B C

Wet Mass (g) 521.0 522.4 523.4

Dry Mass (g) 491.6 491.7 492.1

Absorption (%) 2.5 2.4 2.3

Determine in percentage: (a) total moisture content, and (b) free moisture content for each sample and the average of the three samples.

Sample A

Mass of water - 521.0 – 491.6 = 29.4 g

Total Moisture Content -

Free Moisture Content - 5.9 – 2.5 = 3.4%

Sample B

Mass of water - 522.4 – 491.7 = 30.7 g

Total Moisture Content -

Free Moisture Content - 6.2 – 2.4 = 3.8%

Sample C

Mass of water - 523.4 – 492.1 = 31.3 g

Total Moisture Content -

Free Moisture Content - 6.4 – 2.3 = 4.1%

5.9 Samples of coarse aggregate from a stockpile are brought to the laboratory for determination of specific gravities. The following weights are found:

Mass of moist aggregate sample as brought to the lab: 5298g

Mass of oven dried aggregate: 5216g

Mass of aggregates submerged in water: 3295g

Mass of SSD aggregate: 5227g

Find:

a) The aggregate bulk dry specific gravity -

b) The aggregate apparent specific gravity -

c) The moisture content of stockpile aggregate (report as a percent) - 5298 – 5216 = 82

d) Absorption (report as a percent) -

5.12 Calculate the percent voids between aggregate particles that have been compacted by rodding, if the dry-rodded unit weight is 72.5 lb/ft³ and the bulk dry specific gravity is 2.639.

100 – 44.1 = 55.9%

5.17 Calculate the sieve analysis of the following aggregate and plot on a semilog gradation paper. What is the maximum size? What is the nominal maximum size?

Sieve Size Amount Retained, g Cumulative Amount Cumulative Percent Percent Passing

Retained, g Retained

25mm (1in.) 0 0 0 100

9.5mm (3/8 in.) 47.1 47.1 7 93

4.75mm (No.4) 239.4 286.5 45 55

2.00mm (No.10) 176.5 463.0 72 28

0.425mm (No.40) 92.7 555.7 87 13

0.075mm (No.200) 73.5 629.2 98 2

Pan 9.6 638.8 100 0

Total 638.8

Maximum Size: 25mm

Maximum Nominal Size: 0.075mm