道材第一章作业答案道材第一章作业答案.doc

Chapter 1 There are two kinds of stone, and the test results are shown in following table. Which kind of stone has better performance? Properties A B True density (cm3) 2.8 2.5 Bulk density (cm3) 2.6 2.5 Saturated-water coefficient (%) 0.75 0.65 Solution: B has batter performance. Reasons: (1)Porosity of stone:,the higher the porosity of stone is ,the lower the degree of stone density is .B shows a high degree of rock fissures(裂缝).(2)Saturated-water coefficient :,The anti-freezing of stone B is better than that of stone A Solution: Stone: Compressive strength (strength indexes) Uniaxial compression test (test methods) Aggregate: Crushing value (strength indexes) Make standard sample loaded under the specified conditions ,and test the percentage of passing mass on 2.36mm standard sieve after being crushed (test methods)： Please describe the classification of agg. from deferent perspectives. Solution: 1)Material sources：a. gravel b. crushed agg. 2) Grain size: a. fine agg. b. coarse agg.（cement concrete 4.75 mm asphalt mixture 2.36 mm） 3) Composition: a. acid agg(SO265%) b. alkali agg (52%) 4. There are two kinds of aggregate, and the test results are shown in following table. Please describe the difference of the performance of these two kinds of aggregate. Properties A B Crushing value (%) 12 9 Polishing value 58 40 Los Angeles abrasion ratio (%) 8 5 Solution: 1) Crushing value: The lower of the value, the better compressive strength of coarse aggregate is. So B has better compressive strength. 2) Polishing value: The higher of the value, the better anti-polishing aggregate is. So A has better anti-polishing. 3) Los Angeles abrasion ratio: The lower of the value, the better anti-abrasion of coarse aggregate is. So B has better anti-abrasion. Crushing value Qa increase, strength decrease. Polishing value PSV increase, anti-polishing increase. Impact value AIV increase, anti-impacting decrease. Abrasion value Q increase, anti-abrasion d