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Effect Of Crushed Concrete As Coarse Aggregates In Production Of Concrete
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CHAPTER TWO
2.0 LITERATURE REVIEW
The function of aggregate has the influence of the construction quality, therefore, the type and quality of aggregate are very important to be concerned. The fine and coarse aggregates generally use 10% to 25% of the concrete volume (20% to 35% by mass) and will influence the concrete’s freshly mixed and hardened properties, mixture proportions, and economy. Moreover, fine aggregate usually consists of natural sand with particles around 4.75mm (0.2 in); then in terms of coarse aggregate it is usually combination of gravels or crushed stone with particles larger than 4.75 mm (0.2 in.) and generally between 9.5 mm and 37.5 mm (3/8 in. and 11/2 in.) (Gomez, 2003). Then, the natural aggregate consists of gravel and sand can be used after those materials through processing. The process of materials for natural aggregate is only minimal process through the dug or dredged from a pit, river, lake, or seabed (Gomez, S.M 2003).
Moreover, in terms of Crushed Coarse Aggregate use will influence high water absorption of crushed aggregate, of concrete (Fumoto and Yamada, 2006). This is due to the migration of water absorbed by the aggregate to the paste around particles of aggregates, then, the water absorption will influence volume of water and pores in the paste. Recycled fine aggregate has high water absorption because it contains a large quantity of hydrated cement paste from the demolished concrete. Increasing the level of cleanliness of crushed concrete, in terms of the amount of mortar adhering to aggregate particles, has been found to improve the workability, mass per unit volume and compressive strength of the concrete and to reduce the air content (Montgomery and Sturgiss, 1996).
2.1 CRUSHED AGGREGATE CONCRETE
The crushing characteristics of hardened concrete are similar to those of natural rock and are not significantly affected by the grade or quality of the original concrete. Recycled aggregates produced from all but the poorest quality original concrete can be expected to pass the same test required of conventional aggregates. Recycled aggregate can be batched, mixed, transported, placed and compacted in the same manners as convention concrete. Special care is necessary when using fine recycled aggregate. Only up to 10% - 20% recycled fine aggregate is beneficial. The aggregate should be tested at several substitution rates to determine the optimal rate.
2.2 SIZE DISTRIBUTION
Generally, a series of successive crushers are used, with oversize particles being returned to the respective crusher to achieve desirable grading. The best particle distribution shape is usually achieved by primary crushing and then secondary crushing, but from an economic point of view, a single crushing process is usually most effective. Primary crushing usually reduces the Construction and Demolition concrete rubble to about 50 mm pieces and on the way to the second crusher, electromagnets is used to remove any metal impurities in the material (Tsung, N.A 2006).
2.3 CLASSIFICATION OF AGGREGATES
Aggregates are generally classified as below:
i. Natural Aggregate: Construction aggregates produced from natural sources such as gravel and sand, and extractive products such as. Crushed rocks, Sand and gravel, crushed river gravel.
ii. Manufactured Aggregate: Aggregates manufactured from selected naturally occurring materials, by-products of industrial processes or a combination of these, some of the examples are Foamed Blast Furnace Slag (FBS), Fly Ash Aggregate, Manufactured Sand, Polystyrene Aggregate (PSA), Expanded Clays, Shale's and Slates.
iii. Crushed Aggregate: Aggregates derived from the processing of materials previously used in a product and/or in construction, some of the examples are Recycled Concrete Aggregate (RCA), Recycled Concrete and Masonry (RCM), Reclaimed Aggregate (RA) Reclaimed Asphalt Pavement (RAP), Reclaimed Asphalt Aggregate(RAA) Glass Cullet, Scrap tiers, Used Foundry Sand etc
2.4 SOURCES OF CRUSHED AGGREGATES
Traditionally, Portland concrete aggregate from the demolition construction are used for landfill. But now days, Portland concrete aggregate can be used as a new material for construction use. Crushed aggregates are mainly produced from the crushing of Portland concrete structure and buildings. The main, reason for choosing the structural building as the source for aggregate is because a huge amount of crushed demolition Portland cement concrete can be produced.
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ABSRACT - [ Total Page(s): 1 ]ABSTRACTIn the face of a possible scarcity of natural aggregates in the future in line with sustainable construction, this research investigates the feasibility of the use of recycled coarse aggregates as an alternative to natural coarse aggregates in structural concrete. The recycled coarse aggregate used in the research was processed from waste concrete. The percentage of recycled coarse aggregates by weight of all in aggregates in the test mixes were 0%, 5% 10% 20% and 30 % respectively. Th ... Continue reading---
LIST OF TABLES - [ Total Page(s): 1 ]LIST OF TABLESTable 3.1: Proposed Mixes Proportions by weight Table 4.1a: Aggregate Impact and Crushing Value Test Table 4.1b: Aggregate Impact and Crushing Value Test Table 4.2b: Below shows the particle size distribution of fine aggregate used. Table 4.2c: Below shows the particle size distribution of coarse aggregate used Table 4:3 Compressive Strength for Natural Aggregate Table 4.4: Compressive Strength for Recycled Aggregate at 5% replacement Table 4.5: Compressive Strength for Rec ... Continue reading---
LIST OF PLATES - [ Total Page(s): 1 ]PLATESPlate 1: Pictorial Illustration of workability of concrete Plate 2: Determination of density of concrete Plate 3: Testing of compressive strength of concrete ... Continue reading---
LIST OF FIGURES - [ Total Page(s): 1 ]LIST OF FIGURESFigure 4.1: Particle size distribution of fine aggregate Figure 4.2: Particle size distribution of crushed concrete Figure 4.3: Particle size distribution of Coarse Aggregate Figure 4.4: Compressive Strength for Natural Aggregate Figure 4.5: Compressive Strength for Recycled Aggregate at 5% Replacement Figure 4.6: Compressive Strength for Recycled Aggregate at 10% Replacement Figure 4.7: Compressive Strength for Recycled Aggregate at 20% Replacement Figure 4.8: Com ... Continue reading---
TABLE OF CONTENTS - [ Total Page(s): 1 ]TABLE OF CONTENTSTITLED PAGECERTIFICATION DEDICATION ACKNOWLEDGMENT ABSTRACT TABLE OF CONTENT LIST OF TABLE LIST OF FIGURE CHAPTER ONE: INTRODUCTION 1.0 Background of the study 1.1 Problem Statement 1.2 Aim and Objectives 1.3 Justification of the study 1.4 Scope of the study CHAPTER TWO: LITERATURE REVIEW2.0 Literature Review 2.1 Crushed Aggregate Concrete 2.2 Size Distribution 2.3 Classification of Aggregate 2.4 Source ... Continue reading---
CHAPTER ONE - [ Total Page(s): 2 ]CHAPTER ONE INTROUDUCTION1.0 Background to the studyConstruction and Demolition Waste (C&D) is produced during new construction, refurbishment or renovation of buildings. Demolition waste includes materials from complete building removal as well as partial removals when aspects of the buildings are retained. Construction and Demolition waste includes bricks, concrete, masonry, soil, rocks, lumber, paving materials glass, plastics, aluminum, steel, drywall (gypsum), plywood (formwor ... Continue reading---
CHAPTER THREE - [ Total Page(s): 4 ]CHAPTER THREE METHODOLOGY3.0 Research Methodology Investigation to determine moisture content, density test, Aggregate Crushed Value, Aggregate Impact Value, Slump test, Water absorption, Sieve Analysis and Compressive strength test was carried out. The total of sixty (60) concrete cubes of different mixes proportions were prepared with varying percentage. From each mixture 3 cubical specimens of 150mm x 150mm x 150mm were prepared and strength were ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 8 ]The compressive strength result shown that zero percent (0%) of crushed concrete has the highest strength value when compared to other percentages.4.4 Water Absorption RateThe water absorption coefficient test approach employed in this research is based on outlined in EN ISO 15148: -2002 It is significant that the specimens have the same initial moisture content. In this project, 150mm3 concrete cubes cured for 7, 14, 21, and 28 days, followed by drying at 105ËšC in the oven for a further ... Continue reading---
CHAPTER FIVE - [ Total Page(s): 1 ]CHAPTER FIVE5.0 CONCLUSION i. The research has demonstrated that the recycled aggregate (RCA) processed from waste concrete has poor mechanical and physical properties as compared to natural aggregate (NA). The existing mortar content of the RCA was the main cause for poor quality since it lowered its strength and increased its water absorption. ii. The test shows that crushed concrete cannot conveniently be used in the production of new concrete for construction.5.1 R ... Continue reading---
REFRENCES - [ Total Page(s): 1 ] REFERENCES Ajdukiewiez, A. and Kliszczewicz, A., (2002) Influence of recycled aggregates on mechanical properties of HS/HPC. Cement and Concrete Composites 24, pp 269-279.Chetna M Vyas, Darshana R Bhatt, (2013) Destructive Strength Properties of Recycled Coarse Aggregate, ISSN: 2278-3075, Volume2, Issue.Fumoto, T. and Yamada, M., (2006) Durability of Concrete with Recycled Fine Aggregate., American Concrete Institute, SP234, Durability of concrete, Seventh IntConf, Montr ... Continue reading---
