A PROCESS FOR MANUFACTURING PLASTIC BRICKS
FIELD OF INVENTION
[0001] The embodiment herein generally relates to the field of manufacturing technology. More specifically, the invention provides a process for manufacturing a plastic brick for construction.
BACKGROUND AND PRIOR ART
[0002] India is experiencing rapid economic growth however as the economy grows so does India’s impact on the environment, both in terms of waste and greenhouse gases. Annual plastic consumption in India is predicted to rise from 12 million to 20 million tons by 2020 which poses a serious environmental threat as most of this plastic is either incinerated or discarded due to India's poor waste management infrastructure.
[0003] A major problem for India as the economy grows at an ever increasing rate, is income inequality and the lack of improvement in the quality of life in rural communities. Only 16 percent of rural households have access to basic sanitation facilities and, hence open defecation is prevalent in these rural communities, which leads to a lack of personal hygiene and contaminated water supplies. As a result over 7 million children die each year due to diarrhea and other water sanitation-related diseases. There is an urgent need to utilize the available human resource in addressing these challenges. Therefore plastic, which plays a major role in polluting these water bodies has to be recycled and used promptly to reduce the problems caused by poor waste management and sanitation structures.
[0004] Therefore, there is a need to develop a process for manufacturing plastic bricks and thereby resulting in effective waste management. Further, there is a

need to manufacture the plastic brick for construction purpose and thereby providing sufficient sanitation structures.
OBJECTS OF THE INVENTION
[0005] Some of the objects of the present disclosure are described herein below:
[0006] A main object of the present invention is to provide a process for
manufacturing plastic bricks.
[0007] Another object of the present invention is to provide plastic bricks that
can be used for construction purposes.
[0008] Still another object of the present invention is to provide plastic bricks
having high compressive strength, tensile strength and reduced water absorption
rate.
[0009] Yet object of the present invention is to provide a process that consumes
less time for manufacturing the plastic bricks.
[00010] Another object of the present invention is to provide a simple and cost
effective process for manufacturing the plastic bricks.
[00011] The other objects and advantages of the present invention will be
apparent from the following description when read in conjunction with the
accompanying drawings, which are incorporated for illustration of preferred
embodiments of the present invention and are not intended to limit the scope
thereof.
SUMMARY OF THE INVENTION
[00012] In view of the foregoing, an embodiment herein provides a process for manufacturing plastic bricks for construction. According to an embodiment, the process for manufacturing plastic bricks comprising the steps of combining a filler sand and shredded low density polyethylene (LDPE) at a predetermined ratio to

achieve a pre-determined total mass, mixing the filler sand and the LDPE continuously in a large metal pan using a trowel to obtain an even distribution mixture, heating the mixture to a pre-determined temperature for a period of time until a dark grey colour of the mixture is obtained, filling the mixture in a mould to full capacity, pressing the mixture in the mould using a hydraulic press provided with a pre-determined load, leaving the mixture under the hydraulic press for a period of time; and removing the load and thereby forming the plastic brick. According to an embodiment, the plastic brick is provided with an interlock design.
[00013] According to an embodiment, the predetermined ratio is 1:1 ratio to achieve a total mass of approximately 2kg-4kg. According to an embodiment, the pre-determined temperature is in a range of 140oC-180oC. According to an embodiment, the period of time required for heating the mixture until a dark grey colour is obtained is in a range of 15-20 minutes. According to an embodiment, the pre-determined load is in a range of 17kN-20kN. According to an embodiment, the period of time the mixture in the mould is left under the press is around 5 minutes. According to an embodiment, the filler sand is river sand. According to an embodiment, compressive strength of the plastic brick is 14.0 N/mm3. According to an embodiment, wherein average split-tensile of the plastic brick is 14.2 MPa. According to an embodiment, wherein water absorption rate of the plastic brick is 1.01%.
[00014] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and

numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[00015] The detailed description is set forth with reference to the accompanying
figures. In the figures, the left-most digit(s) of a reference number identifies the
figure in which the reference number first appears. The use of the same reference
numbers in different figures indicates similar or identical items.
[00016] Fig.1 illustrates a flow chart showing a process for manufacturing the
plastic brick, according to an embodiment herein;
[00017] Fig.2 illustrates a perspective view of the plastic brick, according to an
embodiment herein; and
[00018] Fig. 3 illustrates a plot of thermal conductivity against time as
determined by the thermal conduction tests of the two specimens; according to an
embodiment herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[00019] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice

the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[00020] As mentioned above, there is a need to manufacture the plastic brick for construction purpose and thereby providing sufficient sanitation facilities.The embodiments herein achieve this by providing a process for manufacturing plastic bricks and thereby resulting in effective waste management. Referring now to the drawings, and more particularly to FIGS. 1 through 2, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[00021] Fig.1 illustrates a flow chart 100 showing a process for manufacturing the plastic brick according to an embodiment herein. According to an embodiment, the process for manufacturing plastic bricks 200 comprising the steps of combining 101 a filler sand and shredded low density polyethylene (LDPE) at a predetermined ratio to achieve a pre-determined total mass, mixing 102 the filler sand and the LDPE continuously in a large metal pan using a trowel to obtain an even distribution mixture, heating 103 the mixture to a pre¬determined temperature for a period of time until a dark grey colour of the mixture is obtained, filling 104 the mixture in a mould to full capacity, pressing 105 the mixture in the mould using a hydraulic press provided with a pre¬determined load, leaving 106 the mixture under the hydraulic press for a period of time; and removing 107 the load and thereby forming the plastic brick 200. According to an embodiment, the plastic brick 200 has an interlock brick design. [00022] Due to the difference in density between the filler sand and LDPE, settlement of sand at the bottom of the pan can result in an uneven distribution of materials, hence constant mixing during heating is required. Manual stirring with

a trowel proves to distribute the mix more evenly than a rotary mixer and allows for large coagulations to be easily broke down. In order to avoid direct contact between the mix and the flame, the pan is heated from underneath using flame. [00023] According to an embodiment, the predetermined ratio is 1:1 ratio to achieve a total mass of approximately 2kg-4kg. According to an embodiment, the pre-determined temperature is in a range of 140oC-180oC. According to an embodiment, the period of time required for heating the mixture until a dark grey colour is obtained is in a range of 15-20 minutes. According to an embodiment, the pre-determined load is in a range of 17kN-20kN. According to an embodiment, the period of time the mixture in the mould is left under the press is around 5 minutes. According to an embodiment, the filler sand is river sand. According to an embodiment, compressive strength of the plastic brick 200 is 14.0 N/mm3. According to an embodiment, wherein average split-tensile of the plastic brick 200 is 14.2 MPa. According to an embodiment, wherein water absorption rate of the plastic brick 200 is 1.01%.
[00024] Fig.2 illustrates an exemplary model of a perspective view of the plastic brick, according to an embodiment herein. The plastic brick has a double cross interlocking brick design. The design has a depth and length of 15 cm X 30 cm respectively. Two circular holes of approximate diameter 30 mm go directly through the centre of each cross to allow for rebar’s to be fitted into a walled structure.
[00025] Test Methodology: The objective of testing is to compare the properties of two different potential filler materials, river sand and M-sand, in order to determine the most appropriate for the application. A total of 5 tests are to be conducted at this stage; compressive strength test, split-tensile strength test, water

absorption test, thermal conductivity test and thermal expansion test. In order to improve the validity of the results each test is repeated, hence a total of 20 specimens are required (10 containing river sand and 10 containing M-sand). A cylindrical specimen is used for testing strength and water absorption, whilst slab specimens are to be used for thermal testing. All specimens are pressed to 20 kN. [00026] (a) Compressive Strength Testing
[00027] Prior to testing of the cylindrical specimens the initial diameter (Di) and initial length (Li) is measured and recorded. Each specimen is positioned into the compressive machine, between two flat plates, such that the length falls parallel to direction of loading. Load is applied at a steady rate until failure is observed; failure is assumed once shear deformation is observed. At failure the maximum load (F) and final length of the specimen (Lf) is recorded. The compressive strength (stress) and strain are calculated using equations 1.1 and 1.2:
[00028] (b) Split-Tensile Testing
[00029] Prior to testing, the initial lengths (Li) of the cylindrical specimens are measured and recorded. Each specimen is positioned in the compressive machine between two parallel plates such that the length falls perpendicular to the loading direction. Load is applied at a steady rate until failure is observed; failure is assumed when splitting becomes visible along the centre of the circular faces. At failure the maximum load (F) and final length (Lf) of the specimens are recorded. [00030] The tensile strength (stress) can be calculated using equation 2:

[00031] (c)Water Absorption Testing
[00032] A brick specimen is immersed fully in clean water at a temperature close
to room temperature for a period of 24 hours. The initial mass (mi) and final mass
(mf) is recorded prior to submersion and after removal from the water
respectively. After removal any excess water is removed from the surfaces of the
specimens using a cloth and the specimens are then left to sit for 3 minutes before
the final mass is determined.
[00033] The percentage of water absorbed by the specimens is calculated using
equation 3:
A[%l=^^xl00 eg. 3
[00034] (d) Thermal Conductivity Testing:
[00035] The guarded hot plate method is followed to determine the rate at which heat is transferred through the specimens and thus predict the insulating characteristics of the material. The machine setup consists of two flat slab specimens placed above and below a hot plate and sandwiched by two cold plates to eliminate any distortion caused by edge losses in unidirectional heat flow. The specimen is composed of three adjacent slab specimens of average dimensions 15 cm x 29 cm x 2 cm. A wooden slab piece is used to replace the top specimen, hence the readings from this sensor are neglected. The specimens initial dimensions are measured and recorded; thickness (l) and cross sectional area (A).

[00036] The inner and outer hot plates are set to 45 V and 50 V respectively. The current (I), voltage (V) and temperature across the specimen are recorded at five minute intervals until the thermal conductivity (k) reaches a constant value. [00037] The thermal conductivity (k) is calculated using equations 4 and 5:
AT = TH-TC=T^+J^-T5 eq.4
k = eq. 5
2XAJT v
Where:
AT= Change in temperature (K)
TC= Temperature of cold plate (o C)
TH = Average temperature of hot plate (o C)
Tx= Temperature of thermocouple x (o C)
[00038] (e) Thermal Expansion Testing
[00039] The initial volume (Vi) of each specimen is calculated before being
placed in an oven set to a temperature of 60oC for a period of 24 hours to
determine the thermal expansion of the material. The temperature is selected
based upon the average climate across India throughout the year, which can reach
up to 50oC. After removal from the oven the final volume (Vf) is determined.
[00040] The volumetric thermal expansion coefficient is calculated using
equation 6:
Where:
aV= coefficient of volumetric thermal expansion (K-1)
AT= change in temperature (K)

[00041] RESULTS & ANALYSIS [00042] (a) Compressive strength
[00043] Table 1: Table of results of compressive test for both river sand and M-sand. Average compressive strength (stress) and strain values are calculated and are compared to the Indian Standards for burnt clay bricks.
Initial Final
Diamete Stress
Filler No. Area /m2 Length Length Force /N -2 Strain
r /m /N m
Sand /m /m
-5.59E-
1 9.70E-02 2.96E-02 1.43E-01 1.35E-01 3.70E+05 1.25E+07 02
RIVER 9.70E- 2.96E- 1.66E- 1.56E- 4.60E+ 1.56E+ -6.02E-
SAND 2 02 02 01 01 05 07 02
1.40E+ -5.81E-
Av. 07 02
-1.16E-
1 9.80E-02 3.02E-02 1.38E-01 1.22E-01 4.20E+05 1.39E+07 01
9.70E- 2.96E- 1.34E- 1.26E- 4.00E+ 1.35E+ -5.97E-
M-SAND
2 02 02 01 01 05 07 02
1.37E+ -8.78E-
Av. 07 02
[00044] As shown in Table 1, using river sand filler increases the average compressive strength by 2% when compared to a similar sample composed of LDPE and M-sand filler. The average compressive strengths of both compositions can be compared to Indian standards for common burnt clay bricks using Table 2. Calculated compressive stresses of 14.0 N/mm2 and 13.7 N/mm2 for the river sand and M-sand samples respectively places both specimens between the 12.5 and 15 class designation.
[00045] Table 2: Classification table of common burnt clay bricks according to average compressive strength outlined by Clause 4.1, IS1077.

Class ATORIJP Co*tpft»l>e Sir*r^lh
Delimitation mt Lin Chun
M/mtn' (kgTtm1)
35 .15 0 (350 J
W JfrO < 300)
25 2S0 (250 >
10 200 (200 J
17-5 17-5 ( IK )
15 150 (I5U)
tl'J 12 5 (125 J
10 100 (100)
7 5 7 5 ( 75 )
5 3 0 ( 50)
3 5 3 S ( 55 )
[00046] According to the traditional classification of brick, a first class brick has a compressive strength no less than 10.5 M N/m2. So according to compressive strength the bricks are first class bricks, from which the bricks can support and single storey sanitation unit. Furthermore, the results indicate that river sand filler reduces compressive strain by 49%, hence river sand filled LDPE bricks are preferable to avoid distortion in a structure. [00047] (b) Tensile strength
[00048] Table 3: Table of results of split tensile strength test for both river sand and m-sand specimens. Average tensile strength (stress) values are compared to the Indian Standards for burnt clay bricks.

[00049] There are currently no available documents outlining Indian standards for the split-tensile strength of clay bricks, hence the data is compared to results from similar split-tensile strength tests that are conducted on waste PET sand filled bottle bricks in Bangladesh. The test is conducted on cylindrical specimens of approximate diameter and length of 150 mm and 300 mm respectively. The specimens are composed of PET bottles that are filled with sand, the bottle bricks are held together by a Portland cement, sand and water mix at a ratio of 1:3:0.6 respectively. When tested to failure at a strain rate of approximately 1.4 to 2.1 N/mm2/min the maximum split-tensile strength reported for a sand filled 100 ml plastic bottle brick cylinder on the 28th day of curing is 1.7 MPa. Strengths of 0.55 MPa and 0.82 MPa are also recorded on days 3 and 7 of curing respectively. The strengths of the bricks are greater than conventional bricks and concrete cylinders.
[00050] Table 3 shows the average split-tensile stresses of the river sand and M-sand specimens to be 14.3 MPa and 12.0 MPa, over 7 times greater than the maximum value reported for the concrete PET sand filled plastic bottle bricks. [00051] (c) Water absorption
[00052] Table 4: Table of results of water absorption test for both river sand and M-sand.



[00053] Table 4 shows the average water absorption as a percentage of the initial specimen weight for both filler compositions. The M-sand specimen is approximately 18 % more absorbent than the river sand specimen. IS 1077 (1992) outlines that absorption for burnt clay bricks must be less than 20% by weight for class 12.5 and below. For higher classes of brick, absorption by weight must be less than 15%. It can therefore be concluded that even though the M-sand specimen is more absorbent than the river sand specimen, both comply to Indian standards and hence are viable for use in construction in terms of water absorption.
[00054] (d) Thermal Conductivity
[00055] Fig. 3 illustrates a plot of thermal conductivity against time as determined by the thermal conduction tests of the two specimens. The m-sand specimen is represented by the red trend line and the river sand is represented by the blue trend line. It is clear that the two specimens have very similar thermal conductivities. The river sand and m-sand specimens have thermal conductivities of 0.67 and 0.72 W m-1 K-1 respectively. Through comparison of the data, the waste plastic construction bricks are less insulating than conventional burnt clay bricks, however the river sand filled specimen exhibits the closest thermal conductivity to the burnt clay bricks, hence is preferable for use in construction. [00056] (e) Thermal expansion coefficient

[00059] From Table 6 it is shown that the volumetric thermal expansion coefficient is 4.23E-03 K-1 and 4.13E-03 K-1 for the river sand and m-sand specimens respectively. This means that the volumetric thermal expansion coefficient of the m-sand is 2.3 % less than river sand specimen. The interlocking plastic bricks are less insulating than conventional burnt clay bricks, though the river sand bricks yield the closest values for thermal conductivity. The thermal expansion coefficients of both filler combinations are ~1000 times greater than conventional clay bricks, which is undesirable for use in high temperature and changing climates such as India.
[00060] A main advantage of the present disclosure is that the plastic brick can be used for construction purposes.

[00061] Still another advantage of the present disclosure is that the plastic brick has high compressive strength, tensile strength and reduced water absorption rate. [00062] Yet advantage of the present disclosure is that the process consumes less time for manufacturing the plastic bricks.
[00063] Another advantage of the present disclosure is that the process for manufacturing the plastic brick is simple and cost effective.
[00064] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

We claim:
1. A process for manufacturing plastic bricks 200; wherein said process
comprising the steps of:
combining a filler sand and shredded low density polyethylene (LDPE) at a predetermined ratio to achieve a pre-determined total mass;
mixing the filler sand and the LDPE continuously in a large metal pan using a trowel to obtain an even distribution mixture;
heating the mixture to a pre-determined temperature for a period of time until a dark grey colour of the mixture is obtained; filling the mixture in a mould to full capacity;
pressing the mixture in the mould using a hydraulic press provided with a pre-determined load;
leaving the mixture under the hydraulic press for a period of time; and removing the load and thereby forming the plastic brick 200.
2. The process as claimed in claim 1, wherein said predetermined ratio is 1:1 ratio to achieve a total mass of approximately 2kg-4kg.
3. The process as claimed in claim 1, wherein said pre-determined temperature is in a range of 140oC-180oC.
4. The process as claimed in claim 1, wherein said period of time required for heating the mixture until a dark grey colour is obtained is in a range of 15-20 minutes.
5. The process as claimed in claim 1, wherein said pre-determined load is in a range of 17kN-20kN.
6. The process as claimed in claim 1, wherein said period of time the mixture in the mould is left under the press is around 5 minutes.

7. The process as claimed in claim 1, wherein said filler sand is river sand.
8. The process as claimed in claim 1, wherein compressive strength of the plastic brick 200 is 14.0 N/mm3.
9. The process as claimed in claim 1, wherein average split-tensile of the plastic brick 200 is 14.2 MPa.
10. The process as claimed in claim 1, wherein water absorption rate of the
plastic brick 200 is 1.01%.