WO2014091442A2

WO2014091442A2 - Solid bricks for construction purpose using bottom ash as main ingredient

Info

Publication number: WO2014091442A2
Application number: PCT/IB2013/060851
Authority: WO
Inventors: Dattkumar Irashetteppa BHASAGI; Uttam Shankar PAWASKAR; Parag Achyut RAILKAR
Original assignee: Tata Power Company Limited
Priority date: 2012-12-12
Filing date: 2013-12-12
Publication date: 2014-06-19
Also published as: WO2014091442A3

Abstract

A process of producing compressed block or bricks for use in building and construction is described herein. The process includes comprises the steps of providing bottom ash about 75% by weight, fly ash and cement, mixing the bottom ash, fly ash and cement to produce a mortar, moulding the mortar in a desired shape, and curing the moulded mortar. The usage of waste material produced by coal combustion to produce solid bricks to be used primarily for construction purposes. The bricks are produced by compressing bottom ash as the primary constituent with fly ash and cement to produce solid bricks having sufficient structural strength for use in building and construction. This present subject matter helps in reducing the problem of disposal of bottom ash that has very little use and causes environmental problem. The solid bricks prepared by the present method are an economical alternative in building construction which in turn help in reducing mining of natural soil used in conventional clay bricks.

Description

SOLID BRICKS FOR CONSTRUCTION PURPOSE USING BOTTOM ASH AS MAIN INGREDIENT

Technical Field

The subject matter relates to utilizing waste material produced by coal -fired boilers of Thermal Power Station to produce useful products. Specifically, the present subject matter provides solid bricks produced by a process utilizing predominantly bottom ash, along with a small amount of fly ash and cement.

Description of the Related Art

Currently a large number of coal-fired power plants are known in the art which are used primarily for generation of electricity. These power plants while producing electricity also annually produce thousands of tons of fly ash and bottom ash, which is the residual waste product produced by burning coal. Bottom ash is produced by the burning of powdered coal which is obtained in clinker form. This ash waste usually falls through a hopper of steam boiler and transported to settling ponds through closed pipe lines for subsequent re-handling and disposal. The sizes of the bottom ash particles vary greatly and some fines passing through a 100 to 200 mesh sieves.

While disposal of fly ash is not a major problem as fly ash has several established usage in industrial applications, the disposal of bottom ash has a number of problems as there are no significant alternatives for use of bottom ash other than landfills. As the bottom ash also contain heavy metal elements and potentially harmful chemical elements, they pose further disposal problem and also require fairly expensive material handling procedures and equipment. Further, disposal of bottom ash can complicate matters as solubilization of contaminants can contaminate underground water aquifers, which are frequently employed as a source of water supply for many people.

On the other hand, major cities need large scale inexpensive housing to provide shelter to its ever growing population. One of the main raw materials for construction of houses and other construction activities is clay bricks. Bricks use soil and soil erosion is a major environmental problem. As can be seen from above if on one hand, there is a challenge of disposal of residual waste products, such as bottom ash, fly ash etc, on the other hand, cheaper residential projects are also a need of the hour wherein soil erosion adds to the crisis.

It has been known in the art to produce bricks from waste material like bottom ash. However, the amount of bottom ash used in such bricks is about 40% to 45% by weight with other ingredient such as fly ash, gypsum, calcium carbonate and lime.

However, even such conventional methods are not sufficient to meet the aforesaid challenges as the ratio of production of the residual waste products is much more than what has been utilized in such method.

Thus, there is a desperate need to prevail over the aforesaid challenge in an environment friendly manner so that the above and other drawbacks are overcome.

SUMMARY

The present subject matter is based on the realization that if normal bricks are replaced by bricks made up of waste material, it will make the bricks cheaper and which in turn will lead to make housing and other construction projects cost effective. Further, this will help to substantially reduce the enormous problem of soil erosion and disposal of bottom ash in particular.

The present subject matter provides a solution to reduce the disposal problem of several thousand tons of bottom ash produced by coal fired plants. Further, the present subject matter provides a means of providing relatively inexpensive brick for construction thus reducing soil erosion and reducing construction costs. As the bottom ash is gainfully utilized, substantial reduction in bottom ash transport cost is also achieved.

The present subject matter is able to utilize the bottom ash to about 75% by weight and other ingredients such as fly ash and cement, thereby vastly improving the consumption of bottom ash in manufacture of bricks and reducing an equivalent amount for disposal.

The present subject matter produces solid bricks by compressing a mixture of bottom ash, fly ash and cement in specific quantities. The bricks prepared by such present process have properties of high compressive strength, low porosity and low thermal conductivity which are suitable for construction of homes, boundary walls and structural support.

The bricks are made by mixing the Bottom Ash, Fly Ash and Cement with machine mixer with water cement ration 0.5 to 0.6, placing the machine mixed Bottom Ash mortar in the moulds, pressing the mortar by manual operated machine (giving 3 to 4 time impact with 50 to 60 KG impact load) and removing the voids by vibrating the moulds. (Frequency 3000 to 3500 VPM (vibration per minute), and keeping the moulded bricks for 7 days curing at atmospheric temperature of 30 degree centigrade.

As can be seen from above, the present subject matter provides a simple and useful process for disposal of significant quantities of Bottom ash and for relieving pressure on scarce landfill resources while also providing a relatively inexpensive material suitable for use in many construction applications, including housing. As the bottom ash usage is significantly increased, the advantages of the present process are two-fold i.e. to use the waste material productively which is otherwise very difficult to dispose, and to reduce the quantity and thus cost of disposal.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings, in which:

FIG. 1 is a Process Flow Diagram explaining the process for making Bottom Ash

Bricks

FIG. 2 is a schematic representation of a mixer used for mixing the ingredients.

FIG. 3 is a schematic representation of the manually operated press machine for pressing moulds into bricks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present subject matter utilizes the Bottom Ash as the main constituent to prepare the solid bricks. Fig 1 shows a Process Flow Diagram for the manufacture of solid bricks. According to the first step 100 of the present process, a mixture of cement, bottom ash, and fly ash is prepared in the ratio of 1 :8:2 by weight respectively and is collected, which is the input to the mixer as shown in Fig 2.

In the second step 200 as depicted in the Process Flow Diagram, the mixer mixes the input to produce a mortar for subsequent operation. The mortar is made in the Drum 6 connected with wheel winch arrangement 1 for rotating the mixer drum 6, as shown in Fig 2, with a speed of about 20-22 revolutions per minute. In one embodiment of the present subject matter, the capacity of the Drum 6 is about 100 liters. Water is added to the dry mixture prepared as above in the Drum 6, with a water cement ratio of about 0.5 to 0.6. The rotation of the Drum 6 is achieved by a Power electric motor 3 having the capacity of 2HP which is connected to wheel winch arrangement 1. The mortar is then removed by lifting the handle 2 from the drum 6. It has a support stand 4 which rests on ground. Front guide wheel 5 and front guide support 7 facilitate movement of mixer. In an embodiment of the present subject matter, pigments can be added to the input to produce mortars having different colors.

In the third step 300 as depicted in the Process Flow Diagram, solid bricks are prepared from the mortar which is produced by the Machine Mixer using a manually operated press machine as shown in Fig 3.

As can be seen from Fig 3, the wet mortar is placed in a plurality of Moulding brackets 10 which are placed on supporting plates 17. The number of Moulding brackets 10 can be reduced or increased as per the number of bricks to be Moulded at a time as would be obvious to a person skilled in the art.

In different embodiments of the present subject matter, the moulding brackets 10 can have different geometric shapes or customized shape to produce bricks with different geometric shapes or customized shapes. With a Handle 8 used for the manual press, the Impact load of around 50-60 kg is given for 4-5 times for pressing the mixture. With the help ofimpression plates 9, the Frog (a grove which is very useful while constructing the wall to make proper bonding in masonry work) is embossed on the top of the Brick. Then with the aid of a vibrator platform 11 with support 12 and 13, which is connected to a Vibrator motor 14, the pressed mixture is vibrated for the around 30-35 seconds to prevent the voids, if any. The MS box 15 (MS = Mild Steel) is brought down by using a Handle 16 in order to remove the moulded solid bricks. Then the Moulded Bricks are lifted and kept in open atmosphere for initial setting with the help of supporting Plates 17.

In the fourth step 400, the bricks are cured for about 7 days to make the bricks usable. Curing is a process of maintenance of a satisfactory moisture content and temperature in concrete for a period of time following placing and finishing of the product, so that the desired properties may develop. Curing has a strong influence on the properties of hardened bricks, proper curing will increase durability, strength, water tightness, abrasion resistance, volume stability, and resistance to freezing and thawing. There are many methods of curing like Ponding and immersion, Fogging and sprinkling and wet coverings etc. The method of curing used in the present subject matter comprises Wet covering method by using cotton mats and rugs to achieve the desired strength.

The final step 500 of the process includes removing the bricks and use for construction activities.

The process according to the present subject matter provides solid bricks that are useful for construction activities. These solid bricks are manufactured by compressing it under the pressure ranging from about 15 to 16 MPA (Mega pascal) i.e. N/mm2. In one preferred embodiment, the mixture is made out of 73 to 75% of Bottom Ash, 16 to 18% of Fly Ash & around 7-8% of Cement with water cement ratio of 0.5 to 0.6. The resultant bricks are cured for 7 days to achieve good compressive strength. The term "Compressive strength" means strength of over above 15 - 16 MPA after 7 day curing. In general the bricks produced have thermal conductivity and porosities similar to that of solid bricks which will be energy efficient building construction material.

According to one aspect of the present subject matter, two bricks can be moulded at a time. The moulding machine as shown in Fig 3 has the capacity of moulding the bricks of around 350 Brick per day. As can be understood by a person skilled in the art, the number of production of bricks can be increased by using different type and capacity machines.

The tables below show comparison of the conventional process and the present process in terms of the proportion of Bottom Ash Brick with the Compressive strength.

Table 1

(MPA = Mega Pascal)

Table 2

As can be seen from Table 1, the bottom ash consumption is increased from 42.5% to 73.91%. The strength of bricks produced by the present process after 7 days of curing is around 15 to 16 MPA for the proportion of 1 :8:2 (cement: bottom ash: fly ash), which is more than the double of the strength achieved by conventional process, as can be seen from Table 2. Following table shows the strength of the Bottom Ash Bricks after 7 days of curing.

Although the present subject matter has been described with reference to specific embodiments, the description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present subject matter as defined.

Claims

We claim:

1. A process of producing compressed block, such as a brick, for use in building and construction, said process comprises the steps of:

providing bottom ash about 75% by weight, fly ash and cement; mixing the bottom ash, fly ash and cement to produce a mortar; moulding the mortar in a desired shape; and

curing the moulded mortar.

2. The process of making compressed block as claimed in claim 1, wherein in the mixture of cement, bottom ash, and fly ash the ratio is about 1 :8:2 by weight respectively.

3. The process of making compressed block as claimed in claim 1, wherein the mixture of bottom ash, fly ash and cement is inputted to a mixer drum.

4. The process of making compressed block as claimed in claim 2, wherein the drum is rotated at a speed of about 20-22 revolutions per minute.

5. The process of making compressed block as claimed in claim 1, wherein moulding the mortar comprising the steps of:

pressing the mortar with an impact load; and

vibrating the pressed mortar.

6. The process of making compressed block as claimed in claim 5, wherein the impact load of around 50-60 kg is given for about 4-5 times.

7. The process of making compressed block as claimed in claim 1, wherein the moulded mortar is cured for seven days.

8. The process of making compressed block as claimed in claim 1, wherein the shape of the compressed block can be of any regular geometric shape or customized shape of different colors.

9. The process of making compressed block as claimed in claim 1, wherein the mortar is moulded by a manually operated press machine.

10. The process of making compressed block as claimed in claim 9, wherein the manually operated press machine comprises:

at least one moulded bracket 10 receiving the mortar, the moulded bracket 10 being placed on at least one supporting plate 17;

impression plates 9 for embossing a frog on the top of the mortar; and

a vibrator platform 11 for vibrating the mortar for around 30-35 seconds.