CODEN (USA): IJCRGG, ISSN: 0974-4290, ISSN(Online):2455-9555 Vol.10 No.8, pp 13-20, 2017
12.34
Abstract : The construction activities in the last few decades have increased many folds in almost all the developing countries of the world. Sand is becoming a scarce commodity globally because of its growing demand day by day. It is the need of time to search such alternative materials that would partially or fully replace sand used in concretes without affecting its quality, strength and other characteristics. In order to reduce time and to improve the filling capacity of highly congested structural members by its own weight without any vibration self-compacting concrete (SCC) is adopted. The primary aim of this study is to explore the feasibility of SCC using foundry sand and hybrid fibres2,5.As the mix design was designed based on finding the optimum percentage of replacement of foundry sand and hybrid fibres based on literature review and development of a suitable mix for SCC using code requirements, that would satisfy the requirements of the plastic state. This offers a unique area of application of self-compacting concrete which can flow through every corner of extensively reinforced area without any vibration and more effective for seismic lo. This research consists of: (i) finding out the percentage of replacement of optimum percentage of foundry sand and hybrid fibres based on literature review; (ii) development of a suitable mix for SCC that would satisfy the requirements of the plastic state.
Cement-based materials are the most abundant of all man-made materials and are among the most important construction materials, and it is most likely that they will continue to have the same importance in the future. However, these construction and engineering materials must meet new and higher demands. When facing issues of productivity, economy, quality and environment, they have to compete with other construction materials such as plastic, steel and wood. One direction in this evolution is towards self-compacting concrete (SCC), a modified product that, without additional compaction energy, flows and consolidates under the influence of its own weight. The use of SCC offers a more industrialised production. Not only will it reduce the unhealthy tasks for workers, it can also reduce the technical costs of in situ cast concrete constructions, due to improved casting cycle, quality, durability, surface finish and reliability of concrete structures and eliminating some of the potential for human error 3,7 . However, SCC is a sensitive mix, strongly dependent on the composition and the characteristics of its constituents. It has to possess the incompatible properties of high flow ability together with high segregation resistance.
To determine the properties and strength of conventional self-compacting concrete without hybrid fibres. To determine the properties and strength of hybrid fibre reinforced self-compacting concrete. To compare the normal self-compacting concrete with hybrid fibre reinforced self-compacting concrete.
Foundry dust is a discarded material from metal industry. It is a mixture of high quality silica sand and some amount of ferrous and non-ferrous material. The physical and chemical properties of foundry dust depends mainly on the type of casting process and the industry sector from its originates.
Foundry sand is basically a fine material. It can be used in many of the same ways as natural or manufactured sand. This includes many civil engineering applications such as formation of embankments, filling low lying areas, hot mix asphalt (HMA) and for making Concrete. Foundry sand is also being used extensively agriculturally as topsoil in agricultural fields.
Glass fibre also called fibreglass. It is material made from extremely fine fibres of glass Fiberglass is a lightweight, extremely strong, and robust material8,9 . Although strength properties are somewhat lower than carbon fibre and it is less stiff, the material is typically far less brittle, and the raw materials are much less expensive. Its bulk strength and weight properties are also very favourable when compared to metals, and it can be easily formed using moulding processes.
Steel fibre is the most common fibre type in the building industry. Steel fibres acts as a bridge to retard their cracks propagation, and improve several characteristics and properties of the concrete. The addition of steel fibres does not change considerably the compressive strength and the modulus of elasticity of concrete but has noteworthy effects on the residual tensile strength and flexural strength
2.1 Cement
Cement is a fine, grey powder. It is mixed with water and materials such as sand, gravel, and crushed stone to make concrete. The cement and water form a paste that binds the other materials together as the concrete hardens. The ordinary cement contains two basic ingredients namely argillaceous and calcareous. In argillaceous materials clay predominates and in calcareous materials calcium carbonate predominates. The cement should be of uniform colour i.e. grey with a light greenish shade and free from any hard lumps. Generally Portland cement is used for SCC.
The sand used for the experimental programme was locally procured and conformed to Indian Standard Specifications IS: 383-1970. The sand will be first sieved through 4.75 mm sieve to remove any particles greater than 4.75 mm and then should be washed to remove the dust. The fine aggregates belonged to grading zone-II.
The maximum size of aggregate is generally limited to 20mm. Aggregate of size 10 mm is desirable for structures having congested reinforcement. The crushed stone is generally used as a coarse aggregate. The nature of work decides the maximum size of the coarse aggregate. Locally available coarse aggregate having the maximum size of 10 mm will be used in our work. The aggregates should be tested as per IS: 383-1970
Generally, water that is suitable for drinking is satisfactory for use in concrete. Water from lakes and streams that contain marine life also usually is suitable. Ordinary potable water of normally pH 7 is used for mixing and curing the concrete specimen.
Foundry sand consists of clean, uniformly sized, high quality silica sand that is bonded to form moulds of both ferrous and non-ferrous metal castings. The physical and chemical characteristics of foundry sand will depend in great part on the type of casting process and industry sector from which it originates. It can be reused several times in foundries but after a certain period it becomes a waste material referred as used pr spent foundry sand. It is basically a fine aggregate that can be used in many ways as natural and manufactured sands.
ViscoCrete 20 HEis a third generation super plasticizer for concrete and mortar. The product is suitable for tropical and hot climatic conditions.ViscoCrete-20 HEis especially suitable for the production of concrete mixes which require high early strength development, powerful water reduction and excellent flowability.
S-Glass or high strength grade glass was originally developed for high strength in scc. The tensile strength of glass fibers is determined by the structure connectivity of the silicate network, notably,by the absence of alkali oxides, which are not readily integrated into the structure. The structure of boron oxide, though being a part of the network, is weaker than that of silicon oxide, and therefore, boron oxide serves as a flux. Several high-strength glass fibers are known S-glass is preferred.
Crimped steel fiber are low carbon, cold drawn steel wire fibers designed to provide concrete with temperature and shrinkage crack control, enhanced flexural reinforcement, improved shear strength and increase the crack resistance of concrete. psi crimped steel fiber complies with astm c1116, standard specification for fiber reinforced concrete and shotcrete and astm a820, type i, standard specification for steel fibers for fiber reinforced concrete. these steel macro-fibers will also improve impact, shatter, fatigue and abrasion resistance while increasing toughness of concrete. Dosage rates will vary depending upon the reinforcing requirements and can range from 25 to 100 lbs/yd³ (15 to 60 kg/m³).
3.1 Cement 3.4foundry Sand Table: 3.1Properties of cement Table: 3.4 Properties of Foundry sand
S.No | Properties | Values |
---|---|---|
1. | Specific Gravity | 3.13 |
2. | Bulk Density | 1440 kg/m3 |
3. | Surface area | 225 m 2/kg |
4. | Initial setting time | 28 min |
5. | Final setting time | 600 min |
S.No | Properties | Values |
---|---|---|
1. | Specific Gravity | 2.4 |
2. | Bulk Density | 2590 kg/m3 |
3. | Moisture Content | 4 % |
3.3 Coarse Aggregate 3.4Fine Aggregate Table:3.3 Properties of coarse aggregate Table:3.2 Properties of fine aggregate
S.No | Properties | Values |
---|---|---|
1. | Specific Gravity | 2.7 |
2. | Bulk Density | 1660 kg/m3 |
3. | Size | 10 mm |
S.No | Properties | Values |
---|---|---|
1. | Specific Gravity | 2.60 |
2. | Bulk Density | 1660 kg/m3 |
Materials | Density (g/cm3) | Tensile Strength | Young modulus |
---|---|---|---|
(MPa) | (GPa) | ||
S-Glass | 2.48 | 4590 | 91 |
4.1 Fresh Properties
SCC containing different proportion of waste foundry sand and flyash was tested for Slump flow, V-funnel, U-Box, L-box. The results of fresh properties of all Self-compacting concretes with waste foundry sand and hybrid fibres are included in table below. As per EFNARC, slump flow of t30cm time ranging from 3 to 6seconds is considered adequate for a SCC,which is an indication of a good deformability. In terms of slump flow, all SCCs does not exhibited satisfactory slump flows in the range of 5 to 10 seconds except MIX 1.
Table 4.1Fresh concrete test calculation for M30
Combination | Slump Flow (Sec) | V-Funnel (Sec) | L-Box | U-Box (Cm) |
---|---|---|---|---|
MIX 1 | 5 | 14 | 0.80 | 30 |
MIX 2 | 7 | 15 | 0.77 | 32 |
MIX 3 | 9 | 13 | 0.73 | 33 |
MIX 4 | 10 | 11 | 0.70 | 35 |
As per EFNARC, V-funnel time ranging from 6 to 12 seconds is considered adequate for a SCC. The V-funnel flow times were in the range of 11-15 seconds. Test results of this investigation indicated that all SCC mixes does meet the requirements of allowable flow time except MIX-1. The L-box ratio H2/H1 for the mixes was above 0.8 which is as per EFNARC standards. The L-box ratio H2/H1 for the all mixes were 0.8 to 0.70. Test results of this investigation indicated that all SCC mixes does meet the requirements of allowable ratio H2/H1 except MIX-1. U-box difference in height of concrete in two compartments was in Properties of Self-Compacting Concrete Incorporating Waste Foundry Sand and hybrid fibres the range <30cm. U-box difference in height of concrete in two compartments of all mixes were 30cm to 35cm. All the fresh properties of concrete values were nearly equal to that of the values given by European guidelines.
4.2 Hardened Properties
4.2.1 Compressive Strength
Effect on compressive strength of M30 Grade concrete mixes MIX-1 (10%FS&1% HF), MIX-2 (10%FS &1.5% HF), MIX-3 (10%FS &2% HF), and MIX-4(10%FS &2.5% HF), at the age of 7, 28days are shown below
45 40 35 30 25
39.9 | ||||
---|---|---|---|---|
33.2 | 35.65 | 34.87 | ||
28.9 | ||||
23.25 | 24.6 | 25.85 | ||
15
10 5 0 mix 1 mix2 mix3 mix4
Fig 4.1 comparison of compressive strength test results
When the replacement of fine aggregate with 10% foundry sand , 1% hybrid fibre it gives good results in compressive strength with increase in 11% thancontrolscc. Whenthe replacement of fine aggregate with 10% foundry sand , 1.5% hybrid fibre it gives good results in compressive strength, of increase in 19.5%.When the replacement of fine aggregate with 10% foundry sand , 2% hybrid fibre it gives good results in compressive strength, with increase in 30% than normal scc.Whenthe replacement fine aggregate with 10% foundry sand, 2.5% hybrid fibre it gives good results in compressive strength, with increase in 11.6% than normal scc.
4.2.2 Split Tensile Strength
Effect on split tensile strength of M30 Grade concrete MIX-1 (10%FS &1% HF), MIX-2 (10%FS &1.5% HF), MIX-3 (10%FS &2% HF), and MIX-4(10%FS &2.5% HF), at the age of 7, 28days are shown below
5
4.5 4
3.5 3
4.175 | 4.425 | 4.13 | ||
4.025 | 3.76 | |||
3.37 | 3.47 | 3.55 | ||
2.5
28day
1.5 1
0.5
0 mix 1 mix2 mix3 mix4
Fig 4.2 comparison of split tensile strength test results
When the replacement of fine aggregate with 10% foundry sand , 1% hybrid fibre it gives good results in split tensile strength with increase in 10.7% than control scc. When the replacement of fine aggregate with 10% foundry sand , 1.5% hybrid fibre it gives good results in split tensile strength, of increase in 11.1% than control scc. When the replacement of fine aggregate with 10% foundry sand, 2% hybrid fibre it gives good results in split tensile strength, with increase in 17.7% than normal scc. When the replacement fine aggregate with 10% foundry sand, 2.5% hybrid fibre it gives good results in split tensile strength, with increase in 11% than normal scc.
4.2.3 Flexural Strength
Effect on Flexural strength of M30 Grade concrete mixes concrete MIX-1 (10%FS &1% HF), MIX-2 (10%FS &1.5% HF), MIX-3 (10%FS &2% HF), and MIX-4(10%FS &2.5% HF), at the age of 7, 28days are shown below
3
2.5 2
2.53 | 2.52 | 2.36 | ||
1.92 2.30 | 1.98 | 2.15 | 2.02 | |
1
0.5 0 mix 1 mix2 mix3 mix4
Fig.4.3 comparison of flexural strength test results
When the replacement of fine aggregate with 10% foundry sand , 1% hybrid fibre it gives good results in Flexural strength with increase in 10.7% than control scc. When the replacement of fine aggregate with 10% foundry sand, 1.5% hybrid fibre it gives good results in Flexural strength, of increase in 11.85% than control scc. When the replacement of fine aggregate with 10% foundry sand , 2% hybrid fibre it gives good results in Flexural strength, with increase in 11.8% than normal scc. When the replacement fine aggregate with 10% foundry sand, 2.5% hybrid fibre it gives good results in Flexural strength, with increase in 11% than normal scc.
5.0 Conclusions
5.1 Compressive Strength
5.2 Split Tensile Strength
5.3 Flexural strength
6.0 References
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