[Impact of Aggregates on the Mechanical Benefits of Concrete]

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TABLE OF CONTENTS

CHAPTER 1: INTRODUCTION5

Background of the Study5

Research Statement6

Objectives of the Study7

Research Questions for the Study7

Research purposes8

CHAPTER 2: LITERATURE REVIEW9

Definition on Concrete9

Effect of Maximum Size9

Effect of Relative Density (Specific Gravity)10

Effect of Soundness and Toughness10

Effect of Grading11

Effect of Absorption12

Effect of Mineralogy and Coatings12

Effect of Strength and Stiffness12

Effect of Shape and Texture of Microfines13

Durability performance of concrete made with fine recycled concrete aggregates14

Durability parameters15

Fine recycled concrete aggregate production17

Concrete mix design18

Water absorption by immersion23

Chloride penetration test26

Carbonation resistance27

Physical and mechanical properties of concrete29

CHAPTER 3: EXPERIMENTAL WORK36

Theoretical Framework36

Materials39

Mix design45

Tests procedures47

Experimental Program48

CHAPTER 4: RESULTS AND DISCUSSION49

Physical and mechanical characteristics of aggregates49

Contaminated aggregate properties50

Concrete properties52

Fresh concrete52

Mechanical performances53

Physical characteristics of hardened concrete53

Oxygen permeability53

Water absorption54

Porosity55

Sensitivity to corrosion55

Freeze-thaw resistance56

Physical-chemical properties of the recycled aggregates56

Concrete Mixes57

Test Design59

Density of fresh (UNE 83317:1991) and hardened (UNE 83312:1990 and ASTM C642:97) concrete59

Water absorption59

Compressive Strength60

Tensile splitting strength (UNE 83306:1985)62

Static modulus of elasticity (ASTM C 469)63

Concrete under sustained compressive load63

CHAPTER 5: CONCLUSIONS65

REFERENCES68

APPENDIX82

Table 1: OC (Original Concrete) composition82

Table 2: Propertis of Fine recycled and fine natural aggregates82

Table 3: Mixture composition (/m3)82

Table 4: Mechanical behavior of tested compositions83

Table 5: Absorption of water by immersion83

Table 6: Correlation data for initial capillary model83

Table 7: Coefficient of non steady state migration83

Table 8: Correlation data for carbonation depth83

Table 9: Slab index (UNE-EN 933-3:1997) for the 5-40 mm fraction of 0-40R84

Table 10: Physical properties of the 0-5 mm and 5-40 mm fractions of the 0-40R84

Table 11: Physical properties of the aggregates used84

Table 12: Mix proportion84

Table 13: Mixing procedure for Recycled Concrete85

Table 14: Tests identification85

Table 15: mechanical and Physical properties of NA and RA85

Table 16: Average content in sulphates and chlorides within concrete slabs post contamination86

Table 17: Sulphates and Chlorides content in the aggregates86

Table 18: Recycled Aggregates' Physical-Chemical properties86

Table 19: Basic parameters of proportion87

Table 20: Consistency87

Table 21: Average density (t/m3) of hardened and fresh concrete at 115 and 28 days87

Table 22: Water absorption after immersion (%) and after immersion and boiling (%) at 115 days88

Table 23: Average compressive strength (MPa) at various periods (115, 7, and 28 days)88

Table 24: Average tensile splitting strength (MPa) for the different ages of tests (115, 7, and 28 days)88

Table 26: Average compressive strength (MPa) at 115 days at various speeds89

CHAPTER 1: INTRODUCTION

Background of the Study

Aggregates make up three quarter of the concrete volume, and they not only have effect on the concrete resistance, but also an effect on the domination and stability of that mixture. The stone materials in concrete withstand and transfer the loads of bars (with coarse particles) and by filling the empty spaces (with fine particles) between the other components of concrete. As it is pointed out the stone materials in the concrete are divided into coarse particles and fine particles, first section is granular materials with medium diameter bigger than 5 millimetres and the second section is smaller than 5 millimetres.

From the petrology point of view, aggregates divided into several groups, which have approximately similar properties. Clarification of natural aggregates are based on British standards including of Granit group, Lime group, slate clay group, sandstone group, Porphyry group, Gabbro Group and Quartz group. American concrete institute is also offering clarification for these minerals, which are, contain ...