FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
TITLE OF THE INVENTION
"MULTI-LAYER COMPOSITE PAVEMENT BLOCK AND PROCESS OF
MANUFACTURING THEREOF"
APPLICANT
TATA MOTORS LIMITED of Bombay House,
24 Homi Mody Street, Hutatma chowk,
Mumbai 400 001, Maharashtra, India;
An Indian Company
INVENTORS
MR. Joshi Vivek V and Mr. Karthik Kundulwar of Tata Motors Limited
of Bombay House, 24 Homi Mody Street, Hutatma chowk, Mumbai 400 001,
PREAMBLE OF THE DESCRIPTION
The following specification particularly describes the invention and the manner
in which it is to be performed

FIELD OF INVENTION
The present invention relates to a pavement block manufactured from a mixed sludge obtained from an industrial waste and more particularly, relates to a production of a pavement block by reutilization of ETP sludge of an automobile industry.
BACKGROUND OF INVENTION
In automobile industries lot of waste materials are generated during the production of the vehicles. The waste materials includes scrap, effluent, effluent treated sludge, paint sludge, chemical sludge, biodegradable waste etc. which are generated during various manufacturing process of the vehicles. The Effluent treatment Plant (ETP) sludge generated during the manufacturing process is one of the hazardous waste and it has to be disposed with reference State Pollution Control Board (SPCB) guide lines. As per SPCB guide lines ETP sludge need to be disposed at authorized disposal site where it is incinerated or land filled. During incineration it is burnt to ashes at high temperature (1200 °C) with help of either fuel or electricity in addition to equivalent fuel or electricity consumption it also generates huge amount of carbon dioxide (CO2). In case of disposal by land filling method huge amount of land contaminated permanently. Also, ETP disposal involves high cost. Hazardous waste disposal at authorized site is Rs 26 per Kg of ETP Sludge. The disposal of the ETP sludge is perennial problem for the automobile industries.
As per existing practice, sludge obtained from textile industries, ash from power plants, sewage sludge, garbage incinerated ash and ashes obtained by burning the sludge are being used for making construction or building materials such as bricks, tiles etc. But as far as ETP sludge of automobile industry is concerned, it has never been utilized for making building materials. Thus, the inventors utilize the ETP sludge of the automobile industry to manufacture the pavement blocks or pavement tiles. The ETP sludge characteristics obtained from the automobile are different from the sewage sludge, garbage sludge and other industrial sludge. The chemical analysis of the ETP sludge of the

automobile industry by component authority reveal that the ETP sludge does not contain any heavy metals and oil or grease traces; thus the ETP sludge may be reutilize for making pavement block.
The prior arts which disclose the use of sludge to manufacture building material are underscored below:
US 5,175,134 (Dl) disclose a method of production of ceramic tile from sludge slag. The other materials used alongwith sludge slag are agalmatolite, clay, silica sand and alkaline element. The sludge slag obtained from the sewage is burned and the resultant ash is used for manufacturing ceramic tiles. Another US patent no. 4874153 (D2) provides a method of producing ceramic products (such as floor tiles, paving tiles, tiles for interior or exterior, porcelain, stoneware or chinaware) by using sludge obtained from sewage treatment or the ashes obtained by burning the sludge. The aforesaid prior art Dl and D2 does not uses sludge obtained from automobile industry or dried from of ETP sludge obtained from the automobile industry.
In order to address the aforesaid drawbacks, the inventors provide a method of reutilization of ETP sludge of the automobile industry to produce a pavement block. The reutilization of ETP sludge as a raw material in manufacturing pavement block protect the ' environment from air pollution, land contamination and eliminate the cost loss in disposal of the ETP sludge. The huge amount of CO2 generated during incineration of ETP sludge or contamination of huge land due to land filling of the ETP sludge can be eliminated by utilizing the ETP sludge in manufacturing the pavement block. The disposal of the ETP sludge at authorized site is Rs 26 per Kg. On the other hand single pavement block of 4.5 Kg weight (which contains 1 Kg of ETP sludge) cost is Rs 7 per block. Thus, in 1 kg of disposal cost three pavements tiles are manufactured. Hence, the inventors utilize the abundant available ETP sludge of the automobile industries in a gainful and eco friendly manner to construct a two layer molded pavement block. The ETP sludge is used as a part of raw material for manufacturing double layer pavement block. The manufactured pavement blocks or pavement tiles are of sufficient strength for making footpath, parking

lots, driveways, surfacing and resurfacing of roads, sidewalks and any other walkways, street, taxiways, and tarmacs, and the like. The process of manufacturing the pavement tiles by using ETP sludge is very economical and cost-effective
OBJECTS OF THE INVENTION
The main object of the present invention is to provide a multi-layer pavement block by utilizing the ETP sludge of the automobile industry.
Another object of the present invention is to provide a method of producing two-layer molded composite pavement block by using the ETP sludge as one of the raw material for manufacturing the pavement block.
Another object of the present invention is to reutilize the ETP sludge of the automobile industry in gainful manner.
Another object of the present invention is to reutilize the ETP sludge of the automobile industry in eco friendly manner to protect the air pollution and land contamination.
Another object of the present invention is to eliminate the cost loss in the disposal of the ETP sludge at any authorized disposal site.
Yet another object of the present invention is to provide a pavement block which is economical, cost-effective and having sufficient strength to use for parking lots, driveways, surfacing and resurfacing of roads, sidewalks and any other walkways, street taxiways, residential roads, toll plazas, pedestrian crossings and tarmacs, and the like.
Yet another object of the present invention is to provide a single layer pavement block of suitable strength for making footpath, courtyard, street, garden paths, place of worship, zoos and the like.

SUMMARY OF THE INVENTION
The present invention relates to a multiple-layer composite paving block of sufficient strength for application at moderate load areas. The multiple-layer composite paving block comprises of a first layer obtained from a composite material comprising cement, Effluent Treatment Plant (ETP) sludge, sand, and bonding agents proportionate to the combine weight of said cement and said ETP sludge; and a second layer obtained from a composite material comprising cement, Effluent Treatment Plant (ETP) sludge, aggregate, and sand, wherein said first layer and said second layer contact each other in intimate association to form single unit of said pavement block, and wherein the compressive strength of said first layer is maintained higher than the compressive strength of said second layer of the pavement block. The bonding agents used.in the present invention are lime and calcium chloride.
According to one aspect of the present invention, said first layer cement is present in proportions of about 33% to about 41% by weight of said pavement block, the Effluent Treatment Plant (ETP) sludge is present in proportions of about 18% to about 35% by weight of said pavement block, the sand is present in proportions of about 33% to about 41% by weight of said pavement block, and the bonding agent is present in proportions about 1% to about 2% proportionate to the combine weight of said cement and said ETP sludge.
According to another aspect of the present invention, said second layer cement is present in proportions of about 20% to about 25% by weight of said pavement block, the Effluent Treatment Plant (ETP) sludge in is present in proportions of about 20% to about 25% by weight of said pavement block, the aggregate is present in proportions of about 20% to about 25% by weight of said pavement block, and the sand is present in proportions 30% to about 35% by weight of said pavement block.
According to another aspect of the present invention, said first layer constitutes about 5% to about 15% of the total volume of said pavement block.

According to another aspect of the present invention, said second layer constitutes about 85% to about 95% of the total volume of said pavement block.
According to another aspect of the present invention, said first layer form the uppermost layer of the pavement block.
According to another aspect of the present invention, said second layer form the lower layer of the pavement block.
Preferably, the compressive strength of said pavement block lies in the range of 18N/sq mm to 30N/sq mm.
Preferably, the compressive strength of said lower layer of the pavement block lies in the range of 6N/sq mm to 9N/sq mm.
Preferably, said pavement block is manufactured in the form of rectangular shape or "I" shape.
According to yet another aspect of the present invention, the present invention provides a process of making pavement block, said process comprising the steps of:
- drying of an Effluent Treatment (ETP) sludge completely and then crushing it to powder form;
- mixing of cement, sand, aggregate and said powdered ETP sludge in a predetermined proportion and thereafter adding water as per requirement;
- casting said mixture of cement, sand, crushed stones and the powdered ETP sludge in a die;
- pressing the die to reduce the volume of said mixture with the help of hydraulic press;
- removing the pavement block from the die and placing it on a horizontal surface for hardness;

- curing the pavement block in water for predefined period; and
- removing the pavement block from water and keeping it for drying for predefined time period.
Preferably, said mixture of cement, sand, aggregate and the powdered ETP sludge is pressed to about 20% by volume in the die.
Preferably said aggregate comprises of crushed stones, crushed bricks, crushed concrete, crushed clay tile, slate, limestone, and gravel. The size of said aggregates is approximately 10mm.
According further aspect of the present invention, said pavement block can be manufactured in the form of a single layer pavement block having constituents cement, sand, crushed stones and dried sludge.
According still further aspect of the present invention, said the breaking strength of the single layer pavement blocks lies in the range of lON/sq mm to 12N/Sq mm which is suitable for light load areas.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, explain the invention. In the drawings.
Figure 1 shows a double layer rectangular composite pavement block; and
Figure 2 shows a double layer composite pavement block in the form of "I" shape interlocking structure;

DETAILED DESCRIPTION OF THE INVENTION
An abundant amount of Effluent Treatment Plant (ETP) sludge released from the automobile industry. The ETP sludge is hazardous in nature and being always disposed at an authorized disposal sites. The disposal of ETP sludge is done by incineration or land filing. The incineration of ETP sludge releases huge amount of carbon dioxide in the atmosphere which causes air pollution. In case of disposal by land filling method huge amount of land get contaminated permanently. Also, ETP sludge disposal involves high cost. The disposal of the ETP sludge at authorized site is approximately Rs 26 per Kg. Thus, the disposal of the ETP sludge is constant problem for the automobile industries.
The ETP sludge is semi-solid in nature and it contains moisture and solid waste materials of automobile industry. The proportion of moisture is approximately about 25 % to about 30% by weight and solid scrap is approximately about 70% to about 75% by weight. The contents of ETP sludge are mainly organic matter, calcium, magnesium, chloride, phosphate sludge, paint sludge, chemical sludge, residue spent resins, waste and residue, and negligible traces of iron, oil and greases. The chemical analysis report of the ETP sludge by the competent authority proves that there is no heavy metal content and very negligible terraces of oil or grease are present. Thus the ETP sludge can be reutilize for making building block or constructive unit. In the present invention, the inventors utilize the freely available ETP sludge to manufacture a multi-layer composite pavement block or pavement tiles. The eco-friendly reutilization of the ETP sludge reduces the emission of huge amount of carbon dioxide during incineration of ETP sludge, prevent land contamination and eliminate the cost loss in disposal of the ETP sludge.
The raw materials used in the manufacturing of the multi- layer pavement block are cement, ETP sludge, aggregate materials, course sand, lime and calcium chloride. The aggregate materials include crushed stones, crushed bricks, crushed concrete, crushed clay tile, slate, limestone, quartz, granite, silica and gravel, but not limited to the same. Any other natural aggregate can also be used which serve the same purpose.

Figure 1 shows a double layer composite rectangular pavement block (100) manufactured by using the aforesaid raw materials. The double layer composite paving block comprising an upper layer (100a) obtained from a composite material which comprises of cement, Effluent Treatment Plant (ETP) sludge, sand, and bonding agents proportionate to the combine weight of said cement and said ETP sludge; and a lower layer (100b) obtained from a composite material comprises of cement. Effluent Treatment Plant (ETP) sludge, aggregate, and sand. The upper layer (100a) and the lower layer (100b) contact each other in intimate association to form single unit of the pavement block. The compressive strength of the upper layer (100a) is maintained higher than the compressive strength of the lower layer (100b) of the pavement block. The bonding agent used in the present invention is lime and calcium chloride. The upper layer (100a) of the pavement block comprises of cement in a proportions of about 33% to about 41% by weight of the pavement block, Effluent Treatment Plant (ETP) sludge in a proportions of about 18% to about 35% by weight of the pavement block, sand in a proportions of about 33% to about 41% by weight of the pavement block, and lime and calcium chloride in a proportion of about 1% to about 2% proportionate to the combine weight of said cement and said ETP sludge. The lower layer (100b) of the pavement block comprises of cement in a proportion of about 20% to about 25% by weight of the pavement block, Effluent Treatment Plant (ETP) sludge in a proportion of about 20 % to about 25% by weight of the pavement block, aggregate in a proportion of about 20% to about 25% by weight of the pavement block, and sand in a proportion of about 30 % to about 35% by weight of the pavement block. The upper layer (100a) and lower layer (100b) molded together to form a composite double layer pavement tiles or pavement block (100) as shown in figure 1. The strength of the upper layer (100a) of the pavement block is more than the lower layer (100b) of the pavement block to increase the abrasive strength of the pavement block. The upper layer (100a) comprises of about 5% to about 15% of the total volume of the pavement block (100) and the lower layer (100b) comprises from about 85% to about 95% of the total volume of the pavement block. The strength of the lower layer (100b) of the pavement block (100) lies in the range of 6 N/Sq mm to 9 N/Sq mm. The breaking strength or compressive strength of the pavement block (100) with upper layer and lower layer lies in the range of 18 N/Sq mm to 30 N/Sq mm. Generally the breaking strength of the pavement

tiles or pavement blocks available in the market lies in the range of 7.5 N/Sq mm to 30 N/Sq mm, which is acceptable for the non traffic application. Thus, the double layer pavement tiles can be used non-traffic applications and moderate load areas such as foot path, street, sidewalks, parking lots, driveways, residential roads, toll plazas, pedestrian crossings, taxi ranks, car parks, shopping centre and malls, golf courses and country clubs, zoos, office parks, service stations, indoor areas, places of worship, pool surroundings, patios, freight yards, air port yards; industrial yards, and courtyard, but not limited to the same.
The various experiments were conducted by taking the different proportion of the raw material to manufacture the pavement block of acceptable strength. The results of the various trail or tests conducted for manufacturing a double layer pavement block of 4.5Kg are provided below in Table-1. The invention will be better appreciated with reference to the following tests results, which are illustrative only and not intended to limit the present invention to a particular embodiment.

Composition by wt. %
Mix.Desg Cement ETP-Studge N.Agg. Course sand Lime CaCl2
A.(T) 33:33 33.33 — 33.33 2 1
(B) 22 22 22 34 — —
B- (T) 37.5 25 — 37.5 2 1
(B) 22 22 22 34 — —
C.(T) 41 18 — 41 2 1
(B) 22 22 22 34 — —
D.(T) 37.5 25 — 37.5 .2 1
(B) "22 22 22 34 — —
E-(T) .37.5 25 37.5 2 —
(B) 22 22 22 34 -- —
*l ime ;and CaCL2 added according to the weight of cement + sludge; Top layer; B: Bottom layer
Table-1

Above example-1 shows the proportion of the raw materials for five different combinations (A, B. C, D and E) of upper layer composition and lower layer composition for making a double layer composite pavement tiles of 4.5Kg weight. The combination "D" exhibited the highest compressive strength of 31.8 MPa (shown in shown in table-2). The upper or top layer (T) in combination "D" comprises of cement in proportion of 37.5 % by weight, ETP sludge in proportion of 25% by weight, course sand in proportion of 37.5% by weight, and lime and calcium chloride added in proportion of 2% and 1% respectively according to the combined weight of cement and ETP sludge. The lower layer or bottom layer (B) in combination "D" comprises of cement in proportion of 22 % by weight, ETP sludge in proportion of 22% by weight, aggregates in proportion of 22% by weight, and course sand in proportion of 37.5% by weight. The combination "E" was conducted without calcium chloride and it was found that the overall compressive strength of the double layer pavement block is reduced. Thus, the calcium chloride and lime are used for enhancing the strength of the double layer pavement tiles. The compressive strength details of combination "D" and "E" are shown below in Table-2.

Mis. Design. Compressive Strength (MPa) Water absorption TO
15 days 28 days
D 23.4 3I.8 5,2
E — 26.5 S.O
Table-2
Figure 2 shows a double layer composite pavement block (200) manufacture in the form of "T" shape. There pavement block can be manufactured of various other shapes such as W-shape, S-shapes, X-shape, hexagons, pentagons, octagons, parallelograms, and quite other shapes that defy definition. The different proportion of the raw material taken for manufacturing of the double layer "1" shape pavement block of 4.5K.g weight is provided below in the table-3. The compressive strength of the double layer "I" shape pavement block recorded to be in the range of 12N/Sq mm to 16N/Sq mm after 15 days and 25N/Sq mm to 27.5N/Sq mm after 28 days.

Composition By weight % (For Brick).
M ix. Desg Wt Cement ETP sludge Aggit Sand Lime Cacl2 . Total
Top L (400 gm) % 37.5 25 0 37.5 2 1 (03

gm 150 100 0 150 8 4 •412
Adjusted gm 140 100 0 150 8 4 402
For 10 Bricks gm 1400 1000 0 1500 80 40 4020

Bottom L (4100 gm) % 22 22 22 34 0 0 100

gm 902 - 902 902 1394 0 0 4100
Adjusted gm 900 900 900 1400 0 0 4100
For 10 Bricks gm 9000 9000 9000 14000. 0 0 41000
Table-3
Referring to another embodiment of the invention, a single layer pavement block of suitable strength can be prepared form the composite material comprising cement, sand, crushed stone and ETP dried sludge. The proportion of different raw materials taken for making the single layer pavement block is shown in table-4. The single layer pavement block will be better illustrated with reference to the following composition of the raw materials, which are illustrative only and not intended to limit the present invention to a particular proportion only.

Normal Bricks Cement Sand Crushed Stones ETP Sludge Strength
(Wt. 4.5 Kg) 700 gm 1300 gm 2500 gm NIL 14-16N/Sqmm
Pavement block Cement Sand Crushed
Stones ETP Dried Sludge Strength
(Wt.4.5 Kg) 700 gm (15%) 800 gm (18%) 2000 gm
(44%) 1000 gm
(23%) 10-12N/Sqmm
Table-4

Above table - 4 show the comparison of the raw materials used for manufacturing normal brick of 4.5 Kg weight and the single layer pavement block of 4.5 Kg weight. The ETP sludge is not used in the manufacturing of the normal brick and the compressive strength of the normal brick is approximately 14 N/Sq mm to 16 N/Sq mm. The single layer pavement block manufacture by using ETP dried sludge having compressive strength 10 N/Sq mm to 12 N/Sq mm which is sufficient for light load areas such as footpath, courtyard, street, garden paths, place of worship, zoos and the like, but not limited to the same.
The process of the manufacturing the pavement blocks or pavement tiles by using ETP sludge as one of the ingredient is described herein.
Drying: The Effluent Treatment sludge obtained from the automobile industry was first dried completely and then it was crushed to make a powder form.
Mixing: The cement, sand, crushed stone of approximately 10mm size, and dried ETP sludge were mixed thoroughly in the concrete mixer. After mixing a suitable amount of water was added to the mixer and then again the mixture was blended in the concrete mixture for few minutes.
Pressing: The prepared mixture from the concrete mixture was forced downward into the block mold. The block mold was pressed to reduce the volume of the mixture by 20 percent with the help of a hydraulic press.
Drying: The pavement block was removed from the mold and kept it without disturbance on the fiat surface for approximately 12 hours to 15 hours for hardness.
Curing: The entire lot of pavement blocks was cured in water tank for approximately 14 days.

Drying: The pavement block was removed from the water tank and kept it for drying for approximately 7 to 8 days. The compressive strength of the pavement block was measured and then it will be transported to the desired locations.
The foregoing description is specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof

WE CLAIM
1. A multiple-layer composite paving block of sufficient strength for application at
moderate load areas comprising:
- a first layer obtained from a composite material comprising cement. Effluent Treatment Plant (ETP) sludge, sand, and bonding agents proportionate to the combine weight of said cement and said ETP sludge; and
- a second layer obtained from a composite material comprising cement, Effluent Treatment Plant (ETP) sludge, aggregate, and sand;
wherein said first layer and said second layer contact each other in intimate association to form single unit of said pavement block, and wherein the compressive strength of said first layer is maintained higher than the compressive strength of said second layer of the pavement block.
2. The multiple-layer composite pavement block as claimed in claim 1, wherein in said first layer cement is present in proportions of about 33% to about 41% by weight of said pavement block, the Effluent Treatment Plant (ETP) sludge is present in proportions of about 18% to about 35% by weight of said pavement block, the sand is present in proportions of about 33% to about 41% by weight of said pavement block, and the bonding agent is present in proportions about 1% to about 2% proportionate to the combine weight of said cement and said ETP sludge.
3. The multiple-layer composite pavement block as claimed in any of the above claims 1 and 2, wherein in said second layer cement is present in proportions of about 20% to about 25% by weight of said pavement block, the Effluent Treatment Plant (ETP) sludge in is present in proportions of about 20% to about 25% by weight of said pavement block, the aggregate is present in proportions of about

20% to about 25% by weight of said pavement block, and the sand is present in proportions 30% to about 35% by weight of said pavement block.
4. The multiple-layer composite pavement block as claimed in any of the above claims, wherein said first layer constitutes about 5% to about 15% of the total volume of said pavement block.
5. The multiple-layer composite pavement block as claimed in any of the above claims, wherein said second layer constitutes about 85% to about 95% of the total volume of said pavement block.
6. The multiple-layer composite pavement block as claimed in any of the above claims, wherein said first layer form the uppermost layer of the pavement block.
7. The multiple-layer composite pavement block as claimed in any of the above claims, wherein said second layer form the lower layer of the pavement block.
8. The multiple-layer composite pavement block as claimed in any of the above claims, wherein said bonding agents are lime and calcium chloride.
9. The multiple-layer composite pavement block as claimed in any of the above claims, wherein the compressive strength of said pavement block lies in the range of 18N/sq mm to 30N/sq mm.
10. The multiple-layer composite pavement block as claimed in any of the above claims, wherein said lower layers' compressive strength lies in the range of 6N/sq mm to 9N/sq mm.

11. The multiple-layer composite pavement block as claimed in any of the above claims, wherein said pavement block is manufactured in the form of rectangular shape.
12. The multiple-layer composite pavement block as claimed in any of the above claims, wherein said pavement block is manufactured in the form of interlocking "I' shape.
13. A process of making pavement block comprising the steps of:

- drying of an Effluent Treatment (ETP) sludge completely and then crushing it to powder form;
- mixing of cement, sand, aggregate and said powdered ETP sludge in a predetermined proportion and thereafter adding water as per requirement;
- casting said mixture of cement, sand, crushed stones and the powdered ETP sludge in a die;
- pressing the die to reduce the volume of said mixture with the help of hydraulic press;
- removing the pavement block from the die and placing it on a horizontal surface for hardness;
- curing the pavement block in water for predefined period; and
- removing the pavement block from water and keeping it for drying for predefined time period;

14. The process of making pavement block as claimed in claiml3, wherein said mixture of cement, sand, aggregate and the powdered ETP sludge is pressed to about 20% by volume in the die.
15. The pavement block as claimed in any of the preceding claims, wherein said aggregate comprises of crushed stones, crushed bricks, crushed concrete, crushed clay tile, slate, limestone, and gravel.

16. The pavement block as claimed in any of the preceding claims, wherein said aggregates are of size 10mm approximately.
17. The pavement block as claimed in any of the preceding claims, wherein said pavement block is capable of being manufactured in the form of a single layer pavement block having constituents cement, sand, crushed stones and dried sludge.
18. The pavement block as claimed in claim 17, wherein the breaking strength of said single layer pavement blocks lies in the range of lON/sq mm to 12N/Sq mm.