Claims:We Claim:

1. Paver blocks comprising:
compacted EOF slag or any other slag from primary steel making processes such as BOF, EAF,60 to 85%by wt selected from size range as Fine aggregate (0-4 mm) and coarse aggregate(4-10mm);
Slag cement 15 to 35% by wt;
Admixture namely polycarboxylic ether: 0.2-2 liters/100 kg of cementitious material,
having high compressive strength in the range of 35 MPa to 60MPa.

2. Paver blocks as claimed in claim 1 wherein said ratio of EOF slag of size range as Fine aggregate (0-4 mm) : coarse aggregate(4-10mm); slag cement is in the range of 15 to 50: 15 to 35: 15 to 25 preferably 50:30:15 respectively.

3. Paver blocks as claimed in anyone of claims 1 or 2 comprising of an initial smooth surface layer made of combination of fine aggregate (0 to 2mm) blast furnace slag and flue dust (0.08-2mm)as coloring agent and also in raw mix.

4. Paver blocks as claimed in anyone of claims 1 to 3 comprising:
Water Absorption %: 0.7 to 1.6.
Flexural strength:3.5 to 8.5 MPa
Split tensile strength: 3.5to 7.5MPa
Abrasion resistance index: 1 to 3.

5. Paver blocks as claimed in anyone of claims 1 to 4 comprising energy optimizing furnace(EOF) slag coarse aggregate, EOF slag fine aggregate, Gravel coarse aggregate and slag cement in a ratio of 20 to 40 : 20 to 30 : 20 to 40 : 15 to 30preferably about 30:20:35:15 by weight, with or without an initial layer made of mixer of fine aggregate blast furnace slag and flue dust which act as coloring agent which gives a smooth face having compressive strength of at least 55MPa.
6.Paver blocks as claimed in anyone of claims 1 to 5comprising energy optimizing furnace(EOF) slag coarse aggregate, EOF slag fine aggregate, Flue dust ,Gravel coarse aggregate and slag cement in a ratio of 20 to 40 : 15 to 30 : 10 to 20 :15 to 40: 15 to 30 preferably about 28:19:19:19:15 by weight, with or without an initial layer made of mixer of fine aggregate blast furnace slag and flue dust which act as colouring agent which gives a smooth face having compressive strength of at least 30 MPa.

7. Paver blocks as claimed in anyone of claims 1 to 6 wherein said EOF slag having the composition range comprising by wt%: Si02: 20-35; CaO: 35-50; MgO : 5-10; MnO : 2-10; Al203 : 2-8; FeO: 25-40.

8. Paver blocks as claimed in anyone of claims 1 to 7 wherein said flue dust which act as coloring agent and in raw mix is obtained from Blast furnace gas cleaning plant(GCP) having the composition range comprising by wt%:Si02: 6-10; CaO : 3-8; MgO : 2-5; MnO: 0-4; Al203 : 5-10; Fe203: 50-52.

9. A process for the manufacture of Paver blocks as claimed in anyone of claims 1 to 8 comprising: i) Crushing of EOF slag in to two size range such as Fine aggregate (0-4 mm) and coarse aggregate(4-10mm) and removing Iron particles therefrom ; ii) Mixing of said coarse aggregate and fine aggregate and slag cement in a ratio of 15 to 35 : 15 to 50: 15 to 25by weight; iii) adding water & admixture polycarboxylic etherto cement; iv) thoroughly mixing and v) molding the blocks under instantaneous pressure of at least 1000 pounds per square inch over its entire surface and by vibration compaction for a period of 1-3 minutes for good compacting and obtaining therefrom said paver blocks.

10. A process as claimed in claim 9 comprising providing an initial layer obtained of fine aggregate blast furnace slag and flue dust as coloring agent to give a smooth face of around 3mm which is separately fed into the mold preferably involving a separate color feeder.

11. A process as claimed in anyone of claims 9 or 10 comprising: i) Crushing of EOF slag in to two size range such as Fine aggregate (0-4 mm) and coarse aggregate(4-10mm). ii)Iron particles are removed by magnetic separator. iii) Mixing of material coarse aggregate and fine aggregate which is obtained from step(ii) and slag cement in a ratio of 50:30:15 by weight. iv)water to cement ratio is 3.5and admixture polycarboxylic ether400 ml v) Mixture obtained from iii) and iv) is thoroughly mixed by mechanical mixer by 5-10 minutes and sent to the feeding hopper through conveyor.vi) From feeding hopper it is sent to mold vii) The initial layer is made of mixer of fine aggregate blast furnace slag and flue dust which act as coloring agent which gives a smooth face of around 3mm were separately feed to the mold by color feeder ix)The material obtained from step vi) and vii) is subjected to instantaneous pressure of at least 1000 pounds per square inch over its entire surface and by vibration compaction for a period of 1-3 minutes for good compacting. ix)The product obtained from step viii) is kept in closed chamber for a period of 24 hours followed by curing under ambient temperature for a period of 21 days such as to obtain said paver blocks having compressive strength in the range 50-55 Mpa.(Heavy traffic application)
12.A process as claimed in anyone of claims 9 or 10 comprising wherein the mix design was made involving EOF slag coarse aggregate, EOF slag fine aggregate, Gravel coarse aggregate (6 to 8mm) and slag cement in a ratio of 30:20:35:15 such as to obtain said paver blocks having higher compressive strength in the range 55- 60 MPa. (over heavy traffic application).
13.A process as claimed in anyone of claims 9 to 11 wherein the EOF slag used has the following composition range by (wt%); Si02: 20-35; CaO : 35-50; MgO : 5-10; MnO : 2-10; Al2O3 : 2-8; FeO: 25-40.
14.A process as claimed in anyone of claims 9 to 12 wherein flue dust is used in significant quantity and also as a coloring agent and obtained from Blast furnace gas cleaning plant(GCP) having the following composition range (wt%); Si02: 6-10; CaO : 3-8; MgO : 2-5; MnO : 0-4; Al203 : 5-10; Fe203: 50-52.

Dated this the 7th day of June, 2019
Anjan Sen
Of Anjan Sen & Associates
(Applicant’s Agent)
IN/PA-199
, Description:FIELD OF THE INVENTION
The present invention relates to providing paver blocks comprising Energy optimizing furnace (EOF) slag, Blast furnace slag, Flue dust, Gravel and slag cement and a process for producing the same. More particularly, the invention relates to the usage of maximum percentage of EOF slag and mix design of the paver block. Another mix is prepared with significant addition of Flue dust to manufacture paver blocks with lower compressive strengths. The products developed are considered to be eco-friendly, techno-economically attractive and takes care of the waste generated in the process of steel making and iron making process.

BACKGROUND OF THE INVENTION
Energy optimizing furnace (EOF) is a primary steel making furnace. The basic principle consists of working with combined submerged and atmosphere oxygen blown in an initial charge containing hot metal, preheated solid scrap and fluxes for slag formation. The slag generated in the above process is known as EOF slag. The generation of EOF slag is in huge quantities and is expected to further rise in the near future. The use of EOF slag in combination with other waste materials not only reduces environmental pollution but also produces value added product such as paving blocks useful for various applications.

The slag generated in EOF is rich in iron oxide and lime content and it cannot be used for productive application in cement manufacture or any other civil applications. However, blends of EOF slag up to a certain quantity in coarse and fine aggregate along with cement could be manufactured for pavement concrete blocks.

In iron and steel industry, flue dust is the major excreta produced by blast furnace operations. This flue dust is enriched with valuable iron oxide. The immediate re-use of flue dust will strongly impact the performance of blast furnace, as it is chemically compounded with alkali metals, zinc and chloride. The volatiles form a closed circuit in the blast furnace. Thus the accumulation of flue dust is high in iron and steel industry. The use of significant quantity of Flue dust in combination with other waste materials for the manufacture of paver blocks is another way where the flue dust material accumulating as a plant waste would become a value added product when used in Paver block concrete.

The prior known process for making paver block is by using natural resources only such as river sand, stone aggregate and ordinary Portland cement. The process to produce paving blocks consists of mixing of ordinary Portland cement, sand and stone aggregates with water in a mechanical mixer, casting in a mould, vibrating the mold on a vibration table to give dense packing, curing at ambient temperature for 1 day in 95% humidity and curing in water for 21 days.

PRIOR ART
1. Reference is made to US 7927037 which recites a paver material that has water permeability of on average about 1 inch per hour and compressive strength of an average of about 8000 psi. According to this invention, the paver is manufactured by compression of a mixture consisting of blast furnace slag, sand, gravel and Portland cement. The mixture is compacted into desired shape, size and color is added as required. This invention also provides an environmentally friendly building materials where, rain water and moisture can permeate and pass through the paver material and reach to subterranean water tables. However, the drawback of this prior art is it uses only blast furnace slag, sand and Portland cement. Blast furnace slag due to its silicate nature it is useful for cement plant. But the low value steel slag was not explained. By using sand, the natural resources get depleted and the usage of OPC cement also harmful, because the production of 1 ton of Portland cement produces 1 ton CO2 and requires 4400 MJ energy and thus adversely affects the environment.

2. Reference is made to US 5211895, wherein a process for manufacturing paving blocks from a blend of Portland cement, coal slag aggregate, water, and an acrylic additive is disclosed. The process consists of preparation of mixture, pouring the blend into a non-porous, high-gloss PVC mold followed by vibration casting. Iron oxide colorant was mixed with Portland cement to produce colored pavement blocks. This colorant was mixed with blend at the time of mixing prior to molding. The aggregates used herein are multi-sized, sub-angular (non-round) black, shiny, hard coal slag. According to this invention multi-sizing filling of the voids by angular shapes aggregate enhanced the strength of the paving blocks compressive strength of an average of about 6000 psi. However, the drawback of this prior art is it uses Portland cement as binder. Production of 1 ton of Portland cement produces 1 ton CO2 and requires 4400 MJ energy and thus adversely affects the environment. Use of High gloss PVC mold is costly and it never tells the productivity.

3. Indian Patent IN237111, wherein a process for manufacturing building bricks is disclosed. According to the invention, bricks are produced from a mixture of granulated blast furnace slag, lime and sand mixture and an alkaline activator was added to the mixture which reacted with granulated blast furnace slag and formed a cementitious binder. The mixture was then filled into mould and compacted by pressing or by vibro-casting. However, the drawback of this prior art is that it uses naturally occurring resources such as sand and thus causes depletion of natural resources.

4. BUILDING MATERIALS; Volume: 38; Special Issues: 25th Anniversary Session for ACI 228 -Building on the Past for the Future of NDT of Concrete; Pages:865-871 DOI: 10.1016/j.conbuildmat.2012.09.013;" wherein a process for the production of paving blocks through geopolymerization of red mud, a waste material of aluminum industry and fly ash is disclosed. Geopolymerization was carried out at ambient temperature. The usage of red mud into fly ash geopolymer increased the reactivity. According to this process, the developed paver blocks were environment friendly and had no toxic effect on leaching. This product also satisfied IS 15658 specifications for paving block. However, the drawback of this prior art is that it uses red mud as major ingredient. Since red mud is an extremely fine particle, its handling requires specialized process and is thus not user friendly.

5. Reference is made to US 4098865, which discloses a process by which paving blocks are produced from concrete slurry. The concrete slurry is produced by inter-mixing of the ordinary Portland cement, sand and aggregate with water. The strength development in paving block is due to setting and hardening of the concrete slurry. However, the drawback of this prior art is that it uses naturally occurring resources such as sand and thus causes depletion of natural resources.

6. Reference is made to US 6939077, wherein a process to develop paving blocks using crushed stone, pebbles and blast furnace slag is disclosed. However, the drawback of this prior art is that it uses natural occurring resources such as stone and pebbles thus causing depletion of natural resources

7. Reference is made to EP2970008A1 A process for preparing a composite construction material, comprising the steps of: mixing a particulate composition and a liquid composition to form a slurry mixture, wherein the particulate composition comprises: a ground calcium silicate having a median particle size in the range from about 1 µm to about 100 µm, and a plurality of filler particles comprising fine particles, and wherein the liquid composition comprises: water, and a dispersant; discharging the slurry mixture in a mold; compacting the slurry mixture within the mold and curing the slurry mixture at a temperature in the range from about 20°C to about 150°C for about 1 hour to about 80 hours under an atmosphere of water and CO2 having a pressure in the range from ambient atmospheric pressure to about 60 psi above ambient and having a CO2concentration ranging from about 10% to about 90% to produce a composite construction material in the form of a paving stone or a construction block. However, the drawback of this prior art is it did not explain, what will happen when we use steel slag as raw material and also it requires additional facilities for curing at a temperature in the range from about 20°C to about 150°C.

8. Reference is made to K. Shrimathi, published in International Journal of ChemTech Research, 2017 Vol.10 No.11, pp 194-200, wherein a process for the production of concrete using steel slag, river sand, gravel and Portland cement. In this process the effect of partial replacement of EOF steel slag is studied by keeping the water cement ratio, cement content, method of curing and compaction are constant. The fresh concrete property is studied by Slump Flow test as per IS 1199:1959 and hardened concrete is tested for Compressive Strength, Flexural Strength and Modulus of Elasticity as per IS: 516-1959. The concrete cubes of size 150 × 150 × 150 mm, cylinders of size 150x300mm and prism of size 100× 100× 500mm with 0% and 100% of slag as replacement for natural coarse aggregate were cast. After 24 hours, the specimens were de-moulded and subjected to water curing. After 28 days the specimens were tested as per IS: 516-1959. And conclude that the flexural strength of steel slag aggregate concrete is steadily increasing with increase in cube and cylinder compressive strength. The modulus of elasticity of steel slag aggregate concrete is highly distinct at lower cube compressive strengths and cylinder compressive strength than that of natural aggregate concrete. However, the drawback of this prior art is they used river sand thus causing depletion of natural resources. And it uses Portland cement as binder. Production of 1 ton of Portland cement produces 1 ton CO2 and requires 4400 MJ energy and thus adversely affects the environment. It did not talk about the paver block and higher compressive strength grade like M50, M55.

9. Reference is made to Dr.R.Malathy, Proceedings of the National Conference on Innovations in Concrete and Construction (ICON – 2015) Sona College of Technology, Salem, T.N. wherein a process for the production of concrete using steel slag, gravel and Portland cement. The paver block prepared by replacing fine aggregate by steel slag, coarse aggregate by gravel and the block is molded under a pressure of 1500 MPa. Curing is done after 24 hours after casting. All the tests results are obtained after 28 days of curing. The grade they achieved is M30. However, the drawback of this prior art is, coarse aggregate is completely replaced by gravel which is a natural resource thus causing depletion of natural resources.It only shows the grade of M30 not shows further higher grade.It did not explain the mass production of this grade and also the field trial.

10. Reference is made to AhmedAbdelbary, published in landscape Architecture and Regional Planning2016; 1(1): 18-24 doi: 10.11648/j.larp.20160101.13wherein a process for the production of paver block using steel slag, river sand and Portland cement. This study aims at evaluating the the abrasion resistance by using steel slag in the production of interlock blocks. And concludes that Introducing slag aggregate resulted in in higher abrasion resistance values (up to 119%) compared to dolomite used for the control group. However, the drawback of this prior art is they used river sand thus causing depletion of natural resources. And it uses Portland cement as binder. Production of 1 ton of Portland cement produces 1 ton CO2 and requires 4400 MJ energy and thus adversely affects the environment. It did not tell about the mass production and the field trial.

Thus, in short it may be summarized that the prior art processes have the following limitations:
a) The production cost of paving blocks is relatively high when it uses costly raw materials such as Portland cement, sand and asphalt.
b) The production of paving blocks causes depletion of natural resources when it uses naturally occurring material such as clay, quartz, quartzite, sand.
c)The CO2 generation is relatively high when it uses Portland cement as production of 1 ton of Portland cement generates 1 ton of carbon dioxide.
d)The production of paver block having smooth surface layer by using river sand causes depletion of natural resources.
e) The production of paver block for light traffic area (compressive strength 40-45Mpa) limits the production of paver block for heavy traffic area (compressive strength 50Mpa) and heavy traffic area (compressive strength 55Mpa).
The present invention is thus directed to provide paver block which would be produced by utilizing steel plant wastes, instead of consuming naturally occurring material, and slag cement as binder with reduced CO2 generation yet able to ensure higher compressive strength suitable for heavy-traffic application.
OBJECTS OF THE INVENTION

The basic object of the present invention is thus directed to provide paving blocks produced from abundantly available waste materials such as EOF slag and flue dust for heavy traffic application having compressive strength 55 MPa or more, and an alternative method of production of the same, which eliminates the drawback of known process.

A further object of the present invention is to provide a method for production of paving blocks using EOF slag as main raw material and slag cement act as a binder.

A still further object of the present invention is to provide a method for production of paving blocks involving a mix design of EOF slag fine aggregate, EOF slag coarse aggregate and cement in a ratio of 50:30:15 for heavy-traffic application.

Another object of the present invention is to provide a method for production of paving blocks involving a mix design of EOF slag fine aggregate, EOF slag coarse aggregate, Gravel and cement in a ratio of 30:20:35:15 for over heavy-traffic application.

Yet another object of the present invention is to provide a process of producing paver blocks, which improves the techno economic properties of the product.

A further object of the present invention is to provide a process of producing paver blocks, wherein flue dust is used as coloring agent and produced red colored paver blocks.

Yet another object of the present invention is to use significant quantity of flue dust by replacing EOF fine aggregate for manufacture paver blocks with lower compressive strengths grade such as M20-M35.

A still further object of the present invention is to provide a process of producing paver blocks wherein the products generated are of high compressive strength.

Yet another object of the present invention is to provide a process of producing paver blocks, which uses blast furnace slag as top layer for better surface finish.

A still further object of the present invention is to provide a process of producing paver blocks, in which CO2 generation is significantly reduced as Slag cement is added in the composition.

Yet another object of the present invention is that the entire EOF fine aggregate in the mix can be replaced with blast furnace iron slag.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to provide Paver blocks comprising:
compacted EOF slag or any other slag from primary steel making processes such as BOF, EAF, 60 to 85 % by wt selected from size range as Fine aggregate (0-4 mm) and coarse aggregate(4-10mm);
Slag cement15 to 35 % by wt;
Admixture namely polycarboxylic ether: 0.2-2 liters/100 kg of cementitious material,
having high compressive strength in the range of 35 MPa to 60 MPa.

A further aspect of the present invention is directed to said Paver blocks wherein said ratio of EOF slag of size range as Fine aggregate (0-4 mm): coarse aggregate(4-10mm); slag cement is in the range of 15 to 50: 15 to 35: 15 to 25 preferably 50:30:15 respectively.

A still further aspect of the present invention is directed to said Paver blocks comprising of an initial smooth surface layer made of combination of fine aggregate (0 to 2 mm) blast furnace slag and flue dust (0.8-2 mm) as colouring agent.

A still further aspect of the present invention is directed to said Paver blocks comprising:
Water Absorption %: 0.7 to 1.6.
Flexural strength:3.5 to .8.5MPa..
Split tensile strength: 3.5to 7.5MPa
Abrasion resistance index: 1 to 3.

A further aspect of the present invention is directed to said Paver blocks comprising energy optimizing furnace(EOF) slag coarse aggregate, EOF slag fine aggregate, Gravel coarse aggregate and slag cement in a ratio of 20 to 40 : 20to 30 : 20 to 40 : 15 to 30 preferably about 30:20:35:15 by weight, with or without an initial layer made of mixer of fine aggregate blast furnace slag and flue dust which act as coloring agent which gives a smooth face having compressive strength of at least 55MPa.
A further aspect of the present invention is directed to said Paver blocks comprising energy optimizing furnace(EOF) slag coarse aggregate, EOF slag fine aggregate, Flue dust ,Gravel coarse aggregate and slag cement in a ratio of 20 to 40 : 15 to 30 : 10 to 20 :15 to 40: 15 to 30 preferably about 28:19:19:19:15 by weight, with or without an initial layer made of mixer of fine aggregate blast furnace slag and flue dust which act as colouring agent which gives a smooth face having compressive strength of at least 30MPa.

Another aspect of the present invention is directed to said Paver blocks wherein said EOF slag having the composition range comprising by wt%: Si02: 20-35; CaO: 35-50; MgO: 5-10; MnO: 2-10; Al203: 2-8; FeO: 25-40.

Yet another aspect of the present invention is directed to said Paver blocks wherein said flue dust in small quantity act as colouring agent and in raw mix is obtained from Blast Furnace Gas cleaning plant(GCP) having the composition range comprising by wt%- SiO2 :6-10; CaO:3-8; MgO:2-5; MnO:0-4; Al2O3:5-10; Fe2O3 :50-52.

Still another aspect of the present invention is directed to said Paver blocks wherein iron slag from Blast furnace that has potential to entirely replace fine aggregate in the mix, said iron slag having the composition range comprising by wt%- SiO2 :30-40; CaO:30-40; MgO:8-12; MnO:0.5-2; Al2O3:15-25; FeO :0.5-1.5.

A further aspect of the present invention is directed to a process for the manufacture of Paver blocks comprising: i) Crushing of EOF slag in to two size range such as Fine aggregate (0-4 mm) and coarse aggregate(4-10mm) and removing Iron particles therefrom . ii) Mixing of said coarse aggregate and fine aggregate and slag cement in a ratio of 15 to 35 : 15 to 50: 15 to 25 by weight. iii) adding water to cement & admixture polycarboxylic ether: 0.2-2 liters/100 kg of cementitious materialiv) thoroughly mixing and v) molding the blocks under instantaneous pressure of at least 1000 pounds per square inch over its entire surface and by vibration compaction for a period of 1-3 minutes for good compacting and obtaining therefrom said paver blocks.

A still further aspect of the present invention is directed to said process comprising providing an initial layer obtained of fine aggregate blast furnace slag and flue dust as coloring agent to give a smooth face of around 3mm which is separately fed into the mold preferably involving a separate color feeder.

A still further aspect of the present invention is directed to said process comprising: i) Crushing of EOF slag in to two size range such as Fine aggregate (0-4 mm) and coarse aggregate(4-10mm). ii)Iron particles are removed by magnetic separator. iii) Mixing of material coarse aggregate and fine aggregate which is obtained from step(ii) and slag cement in a ratio of 50:30:15 by weight. iv)water to cement ratio is 3.5and admixture polycarboxylic ether400 ml v) Mixture obtained from iii) and iv) is thoroughly mixed by mechanical mixer by 5-10 minutes and sent to the feeding hopper through conveyor.vi) From feeding hopper it is sent to mold vii) The initial layer is made of mixer of fine aggregate blast furnace slag and flue dust which act as coloring agent which gives a smooth face of around 3mm were separately feed to the mold by color feeder ix)The material obtained from step vi) and vii) is subjected to instantaneous pressure of at least 1000 pounds per square inch over its entire surface and by vibration compaction for a period of 1-3 minutes for good compacting. ix)The product obtained from step viii) is kept in closed chamber for a period of 24 hours followed by curing under ambient temperature for a period of 21 days such as to obtain said paver blocks having compressive strength in the range 50-55 MPa.(Heavy traffic application)
Another aspect of the present invention is directed to said process comprising wherein the mix design was made involving EOF slag coarse aggregate, EOF slag fine aggregate, Gravel coarse aggregate (6 to 8mm) and slag cement in a ratio of 30:20:35:15 such as to obtain said paver blocks having higher compressive strength in the range 55-60 MPa. (over heavy traffic application).
Yet another aspect of the present invention is directed to said process wherein the EOF slag used has the following composition range by (wt%) SiO2:20-35; CaO:35-50; MgO:5-10; MnO: 2-10; Al2O3 : 2-8; FeO:25-40.
A further aspect of the present invention is directed to said process wherein flue dust is used as coloring agent and obtained from Blast furnace gas cleaning plant(GCP) having the following composition range (wt%); Si02: 6-10; CaO : 3-8; MgO : 2-5; MnO : 0-4; Al203 : 5-10; Fe203: 50-52.

The above and other objects and advantages of the present invention are described hereunder in greater details with reference to the following accompanying non limiting illustrative drawing and examples.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1: illustrates a detailed Flowchart of the process steps involved in the production of paving blocks using EOF slag, BF slag, Flue dust and slag cement involving selective mix design to ensure higher compressive strength.
Fig.2: shows stages of Mass production of Paver Blocks.
Fig.3: shows Red Paver Block obtained from Flue Dust-Top.
Fig.4: shows Paver Block in light traffic application.
Fig.5: shows Paver Block in over heavy traffic application.

DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO ACCOMPANYING FIGURE

The present invention relates to provide paver blocks comprising Energy optimizing furnace (EOF) slag, Blast furnace slag, Flue dust, Gravel and slag cement having higher compressive strength suitable for heavy traffic application and a process for producing the same.
EOF slag is generated in the process of primary steel making. The generation of EOF slag is huge and is expected to further rise. Till now, there is no commercial process for utilization of EOF slag. The present invention provides a process which can utilize EOF slag for the preparation of paving blocks thus, having the potential for commercialization. The products developed by this process are eco friendly, techno-economically attractive and will take care of waste generated in steel making processes.
The flue dust is generated in the process of iron making. This has low value due to presence of alkali and leads to landfill.
So the present invention provides a process for the preparation of paving blocks using EOF slag as main raw material and flue dust as coloring agent, wherein the method comprises the following steps:
i) Crushing of EOF slag in to two size range such as Fine aggregate (0-4 mm) and coarse aggregate(4-10mm).
ii)Iron particles are removed by magnetic separator.
iii) Mixing of material coarse aggregate and fine aggregate which is obtained from step(ii) and slag cement in a ratio of 50:30:15 by weight.
iv)Water to cement ratio is 3.5 and admixture polycarboxylic ether400ml.
v) Mixture obtained from iii) and iv) is thoroughly mixed by mechanical mixer by 5-10 minutes and sent to the feeding hopper through conveyor.
vi) From feeding hopper it is sent to mold.
vii)The initial layer is made of mixer of fine aggregate blast furnace slag and flue dust, which act as coloring agent which gives a smooth face of around 3mm were separately feed to the mold by color feeder.
ix)The material obtained from step vi) and vii) is subjected to instantaneous pressure of at least 1000 pounds per square inch over its entire surface and by vibration compaction for a period of 1-3 minutes for good compacting.
x)The product obtained from step viii) is kept in closed chamber for a period of 24 hours followed by curing in water for a period of 21 days.
EXAMPLES:
The following examples are provided by way of illustration of the process according to present invention and therefore should not be construed to limit the scope of the present invention.

EXAMPLE 1:
250 kilograms of EOF slag coarse aggregate and 175 kilograms of EOF slag fine aggregate were taken for the preparation of paving block. These two raw materials are mixed with slag cement of 75 kg in a mechanical mixer in a ratio of 50:35:15. During the mixing water is added in mixer according to water to cement ratio of 3.5and admixture polycarboxylic ether400 ml. This process continuous for 7 minutes. Then the mixture was transferred to the material hopper through conveyor and then to material feeder. The material was sent to the mould by opening of the material feeder. Before the mixture was casted 20 kilogram of blast furnace slag and 10 kilogram of cement was added on the top of the mixture for smooth surface. Finally, the mixture was casted in mould using vibration and compaction with a pressure of 1000psi.The samples were kept in an ambient temperature without sunlight for a period of one day. At last the samples were cured for 21 days. Physical testing such as setting time, compressive strength, flexural strength, water absorption, abrasion resistance and hardness was carried out as per standard test methods.
The properties of the paving blocks obtained based on Test Report of Sample Aare furnished in table 1(a-f) and summarised as follows:
Compressive strength:54Mpa
Water Absorption :0.92
Flexural strength:6.40 MPa
Split tensile strength:5.37 MPa
Abrasion resistance index:1.4
Thaw durability: very Slight scaling
Table 1a:

Table 1b:

Table 1c:

Table 1d:

Table 1e:

Table 1f:

EXAMPLE 2:
EOF slag coarse aggregate: Gravel coarse aggregate: EOF slag fine aggregate: Cement &Water to cement ratio is provided to prepare a mix.
In a typical mechanical mix of the above ingredients in a ratio of 30:20:35:15 and water to cement ratio of 3.5 is made. The typical mix by weight contains 150 kilograms of EOF slag coarse aggregate, 100 kilograms of gravel coarse aggregate and 175 kilograms of EOF slag fine aggregate were taken for the preparation of red colored paving block. These raw materials are mixed with slag cement of 75 kg. This process continuous for 7 minutes. Then the mixture was transferred to the material hopper through conveyor and then to material feeder. The material was sent to the mould by opening of the material feeder. Before the mixture was casted 18 kilogram of blast furnace slag, 2 kilogram of flue dust and 10 kilogram of cement was added on the top of the mixture for smooth surface. Finally, the mixture was casted in mould using vibration and compaction with a pressure of 1000psi.The samples were kept in an ambient temperature without sunlight for a period of one day. At last the samples were cured for 21 days. Physical testing such as setting time, compressive strength, flexural strength, water absorption, abrasion resistance and hardness was carried out as per standard test methods. The properties of the paving blocks obtained based on Test report of sample B are furnished in table 2a-f and are summarised below:
Compressive strength:62 MPa
Water Absorption:1.4
Flexural strength: 4.9 MPa
Split tensile strength:4.9 MPa
Abrasion resistance index:1.8
Thaw durability: very slight scaling

Table 2a:

Table 2b:

Table 2c:

Table 2d:
Table 2e:

Table 2f:

It is thus possible by way of the present invention to provide Paver Blocks made of steel plant waste materials and a method and mix proportion for making interlocking pavers having high compressive strength of an average of 55MPa to 60MPa with the usage of low value materials such as Energy optimized Furnace (EOF)slag, Iron slag and flue dust from blast furnace. For binder, slag cement was used which have less CO2emission when compared to the OPC cement during the manufacturing process. This mixture of EOF slag, Flue dust and slag cement is shaped in to desired shape by vibration and compression of the hydraulic paver block machine. The obtained paver block shows good compressive strength and abrasion resistance suitable for paving application in heavy traffic area.