Claims:We Claim:
1. An apparatus for measurement of expansion of aggregate materials including slag under conditions specified by different standards in a single set-up comprising:
a. bath container for holding anyone or more of water, steam and any liquid under pressurized and high temperature conditions;
b. said container having an inlet for filling the bath container and an outlet for drainage of contents , level sensor for continuously sensing the level of contents in said bath container, heating element with temperature sensor and temperature controller operatively connected for maintaining desired temperature ;
c. atleast one dimension variable aggregate/slag chamber capable of containing variably the aggregate/slag based on the test requirement for its expansion study and measurement housed in said bath container;
d. displacement measurement device cooperatively connected to said aggregate/slag chamber enabling measurement of expansion of said aggregate/slag in said aggregate/slag chamber.
2. An apparatus as claimed in claim 1 wherein said bath container comprises:
a. a doubled walled stainless steel container having an insulator packing in between capable of holding preferably water or any liquid under pressurized and high temperature conditions
b. a drainage valve connected to its bottom
c. a water inlet tube to fill the bath container and
d. a solenoid based level sensor assembly.

3. An apparatus according to anyone of claims 1 or 2 wherein said bath container comprises:

a. said heating element fixed in immersed condition to raise the temperature of the water to the desired value or generate steam as and when required;
b. said temperature sensor preferably thermocouple capable of measuring liquid/steam temperatures continuously said thermocouple connected in a closed loop feedback to said temperature controller for controlling the power to the heating element to maintain a constant set temperature;

c. a stirrer immersed into the bath container and operatively connected to a motor for rotating for desired stirring to maintain the temperature uniformity in the bath container.

4. An apparatus according to anyone of claims 1 to 3 comprising control and display panel including temperature display screen, temperature adjusting knobs for setting the temperatures and the power on/off switch.

5. An apparatus according to anyone of claims 1 to 4, comprising two said aggregate/slag chamber preferably releasably disposed symmetrically within said bath container through closable openings on the top surface of said bath cylinder wherein each said aggregate/slag chamber comprising:
a. perforated top movable plate having a connecting rod and a perforated bottom plate fixed to the chamber;
b. the connecting rod connected to said displacement measurement device capable of measuring the displacement of the top plate for said aggregate/slag expansion measurement;
c. said displacement measurement device supported on the apparatus preferably involving a magnetic stand;
d. the top and bottom perforated disc comprising perforations preferably extending in a series of concentric circles about the centre hole each having a diameter of 4 to 6mm preferably about 5mm which allows the water/steam to freely pass through a slag sample.

6. An apparatus according to anyone of claims 1 to 5 which is capable of carry out testing in compliance with European, Japanese and Indian standards.

7. A method for measuring the expansion of aggregate material/slag samples involving the apparatus as claimed in anyone of claims 1 to 6 comprising the steps where:
a. introducing aggregate material/slag samples filled as per select measurement standard based specified height into the aggregate/slag chamber;
b. filling the bath container with water or steam;
c. placing the filled aggregate/slag chamber into the bath container either immersed in water or steam environment;
d. cooperatively connecting the displacement measurement device to the connecting rod of the top movable plate and recording the first reading of the gauge ;
e. curing the filled aggregate/slag chamber by keeping immersed in water or exposed to steam to a specified duration as per the desired testing standard; and
f. measuring the expansion though said displacement measurement device.

8. A method for measuring the expansion of aggregate material/slag samples as claimed in claim 7 comprising the steps:
a. grading the representative aggregate/slag samples in to the sizes as specified in the standard
b. filling the graded aggregate/slag samples to standard specified height into the aggregate/slag chamber with a scoop and rammed in three equal layers one upon another using a tamping rod;
c. filing the bath container with water or steam;
d. Placing the aggregate/slag containing aggregate/slag chambers into the bath container either immersed in water or steam environment;
e. fixing dial gauge as said displacement measurement device is fixed to the connecting rod of the top movable plate involving a pivot and the first reading of the gauge is recorded;
f. the aggregate/slag chambers is cured by keeping immersed in water or exposed to steam to a specified duration as per the followed testing standard; and
g. measuring the expansion though said displacement measurement device.

9. A method for measuring the expansion of aggregate material/slag samples according to anyone of claims 7 or 8 , wherein readings of the dial gauge are recorded at regular intervals and at the end of the curing period.

10. A method for measuring the expansion of aggregate material/slag samples according to anyone of claims 7 to 9 wherein the percent expansion at each day is measured by dividing the difference between the daily dial gauge reading and the base reading or the final expansion is measured by dividing the difference between final dial gauge reading and the base reading by the initial specimen height and multiplying by 100.

Dated this the 20th day of August, 2015
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

, Description:FIELD OF THE INVENTION
The present invention relates to an apparatus for measurement of expansion of aggregate materials including slag under conditions specified by different standards in a single set-up and a method for such measurement using the apparatus. More particularly, the present invention is directed to an apparatus for measurement of expansion of slag samples, both long term and accelerated swelling, to be used as aggregates in civil construction. Apparatus comprises one isothermal heating bath, capable of storing and heating water up to desired range, equipped with automatic temperature controller with display screen, automatic water level controller, and one stirrer to maintain the uniformity of the temperature inside the water bath. Apparatus consists of slag chamber with perforated top and bottom for complete immersion of slag wherein said single apparatus is capable of carry out testing in compliance with European, Japanese and Indian standards. The top perforated plate is connected through a piston to a displacement measurement device. As the sample expands during the course of experiment, the amount of linear movement of the top plate or the piston is detected by displacement measurement device. This apparatus and the test method specify the procedure to calculate the potential expansion of aggregates like steel slag due to hydration reactions. This method can also be used to evaluate the effectiveness of weathering processes for reducing the expansive potential of such aggregates materials.

BACKGROUND OF INVENTION
It is well known that the iron and steel making processes generate huge amount of slags. The disposal of these slags is a major concern for the steel industry. With increasing capacity of steel production, significant efforts and investments have been made into research over the years to develop the slag processing technologies which enable re-use of slag either directly or through development of slag-based products. Due to rapid urbanization and growing environmental concerns over sand mining and rock crushing, the construction industry is also facing a big challenge to meet the increasing demand of natural coarse and fine aggregates. Owing to the fact that the chemistry and physical properties of iron and steel process slags match the properties of natural aggregates, it is found that one of the major application areas where large quantities of slag can be utilized is in road and civil constructions as replacement of natural aggregates. However, slags must be processed to match the requirements for use as aggregates. In spite of possessing good mechanical properties, direct use of slags as aggregates has not been successful due to its expansion characteristics especially steel slag which shows volumetric instability in the presence of water. Various expansive reactions are the primary reasons for steel slag expansion. The primary reason for volumetric expansion and structural instability of steel slags is the presence of free magnesium oxide (MgO - [CaO + H2O ? Ca(OH)2]) and lime (CaO - [MgO + H2O ? Mg(OH)2]) in its mineralogy which forms low density hydroxides in the presence of water. The swelling nature of steel slag is detrimental to almost all civil engineering applications. Hence, the main challenge to the researchers has been to develop a treatment process to decrease the volume instability caused by the expansive components of steel slag by changing its chemical and/or mineralogical properties and its accurate measurement. In addition to the ageing process, to effectively utilize steel slag in both bound and unbound applications, it is important to assess its swelling/expansion potential or the effectiveness of the ageing treatment. For this purpose, several swelling test methods have been developed and used to assess the expansion potential of steel slag. These testing methods can be classified into two main groups: a) long-term swelling tests and b) accelerated swelling tests. In the long-term swelling tests, steel slag samples are typically immersed in water, and swelling is monitored at room temperature for a long period of time (a minimum of 3-6 months). In accelerated swelling tests, compacted steel slag samples are exposed to hot water or steam in order to accelerate the swelling rate, and swelling is monitored for a shorter period of time (typically ranging from 2 to 14 days). Some of the popular tests being followed in the industry are Long-term Swelling Tests (ASTM D1883), Water-Bath Swelling Test (ASTM D4792), Autoclave Expansion Test (ASTM C151-05), European Steam Test (EN 1744-1), IS-2720, JIS A 5015 etc. Each of these swelling test methods provide a different maximum expansion value for the same steel slag varying from 1.5 % to 15 %. Hence, the limiting values of expansion for a specific application depends also on the type of swelling test performed. Each test requires a different set-up but fundamentally, the process is to expose a particular graded quantity of slag to hot or cold water or steam for a particular time and the change in the volume to be quantified as expansive measurement. It is important to choose the correct test method that best simulates the conditions of the intended application or as required by customer. Due to non-availability of a single general set-up or apparatus to measure expansion of slags following different standards, slag companies utilize multiple set-ups and apparatus. In the present invention a single general set-up or apparatus has been designed, which is capable to measure the slag expansion (both long term and accelerated swelling) under conditions specified by different standards.

OBJECTS OF THE INVENTION

The basic object of the present invention is directed to provide an apparatus for measurement of expansion of aggregate materials including slag under conditions specified by different standards in a single set-up and method of such measurement.

A further object of the present invention is directed to provide a test apparatus for measurement of expansion of slag samples wherein a single general set-up or apparatus is used to measure expansion of slags following different standards in compliance with European, Japanese and Indian standards, so as to facilitate slag companies avoid requirement of multiple set-ups and apparatus.

A still further object of the present invention is directed to provide a test apparatus for measurement of expansion of slag samples wherein both long term swelling test and the accelerated swelling test of slag samples can be performed by the same set-up/apparatus.

A still further object of the present invention is directed to provide a test apparatus for measurement of expansion of slag samples wherein the process of testing using the apparatus is directed to expose a particular graded quantity of slag to hot or cold water or steam for a particular time and the change in the volume to be quantified as expansive measurement.

A still further object of the present invention is directed to provide a test apparatus for measurement of expansion of slag samples wherein the apparatus and method simulates the conditions of the intended application of slag sample or as required by customer to carry out tests under conditions specified by different standards.

A still further object of the present invention is directed to provide a test apparatus for measurement of expansion of slag samples which is more universal in measuring the slag expansion.

SUMMARY OF THE INVENTION

The basic aspect of the present invention is directed to provide an apparatus for measurement of expansion of aggregate materials including slag under conditions specified by different standards in a single set-up comprising:
a. bath container for holding anyone or more of water, steam and any liquid under pressurized and high temperature conditions;
b. said container having an inlet for filling the bath container and an outlet for drainage of contents , level sensor for continuously sensing the level of contents in said bath container, heating element with temperature sensor and temperature controller operatively connected for maintaining desired temperature ;
c. atleast one dimension variable aggregate/slag chamber capable of containing variably the aggregate/slag based on the test requirement for its expansion study and measurement housed in said bath container;
d. displacement measurement device cooperatively connected to said aggregate/slag chamber enabling measurement of expansion of said aggregate/slag in said aggregate/slag chamber.

A further aspect of the present invention is directed to said apparatus wherein said bath container comprises:
a. a doubled walled stainless steel container having an insulator packing in between capable of holding preferably water or any liquid under pressurized and high temperature conditions
b. a drainage valve connected to its bottom
c. a water inlet tube to fill the bath container and
d. a solenoid based level sensor assembly.

A still further aspect of the present invention is directed to said apparatus wherein said bath container comprises:

a. said heating element fixed in immersed condition to raise the temperature of the water to the desired value or generate steam as and when required;
b. said temperature sensor preferably thermocouple capable of measuring liquid/steam temperatures continuously said thermocouple connected in a closed loop feedback to said temperature controller for controlling the power to the heating element to maintain a constant set temperature;

c. a stirrer immersed into the bath container and operatively connected to a motor for rotating for desired stirring to maintain the temperature uniformity in the bath container.

Another aspect of the present invention is directed to said apparatus comprising control and display panel including temperature display screen, temperature adjusting knobs for setting the temperatures and the power on/off switch.

Yet another aspect of the present invention is directed to said apparatus comprising two said aggregate/slag chamber preferably releasably disposed symmetrically within said bath container through closable openings on the top surface of said bath cylinder wherein each said aggregate/slag chamber comprising:
a. perforated top movable plate having a connecting rod and a perforated bottom plate fixed to the chamber;
b. the connecting rod connected to said displacement measurement device capable of measuring the displacement of the top plate for said aggregate/slag expansion measurement;
c. said displacement measurement device supported on the apparatus preferably involving a magnetic stand;
d. the top and bottom perforated disc comprising perforations preferably extending in a series of concentric circles about the centre hole each having a diameter of 4 to 6mm preferably about 5mm which allows the water/steam to freely pass through a slag sample.

Importantly, said apparatus is capable of carry out testing in compliance with European, Japanese and Indian standards.

A further aspect of the present invention is directed to a method for measuring the expansion of aggregate material/slag samples involving the apparatus as described above comprising the steps where:
a. introducing aggregate material/slag samples filled as per select measurement standard based specified height into the aggregate/slag chamber;
b. filling the bath container with water or steam;
c. placing the filled aggregate/slag chamber into the bath container either immersed in water or steam environment;
d. cooperatively connecting the displacement measurement device to the connecting rod of the top movable plate and recording the first reading of the gauge ;
e. curing the filled aggregate/slag chamber by keeping immersed in water or exposed to steam to a specified duration as per the desired testing standard; and
f. measuring the expansion though said displacement measurement device.

A still further aspect of the present invention is directed to a method for measuring the expansion of aggregate material/slag samples comprising the steps of:
a. grading the representative aggregate/slag samples in to the sizes as specified in the standard
b. filling the graded aggregate/slag samples to standard specified height into the aggregate/slag chamber with a scoop and rammed in three equal layers one upon another using a tamping rod;
c. filing the bath container with water or steam;
d. Placing the aggregate/slag containing aggregate/slag chambers into the bath container either immersed in water or steam environment;
e. fixing dial gauge as said displacement measurement device is fixed to the connecting rod of the top movable plate involving a pivot and the first reading of the gauge is recorded;
f. the aggregate/slag chambers is cured by keeping immersed in water or exposed to steam to a specified duration as per the followed testing standard; and
g. measuring the expansion though said displacement measurement device.

According to another aspect of the present invention is directed to said method for measuring the expansion of aggregate material/slag samples wherein readings of the dial gauge are recorded at regular intervals and at the end of the curing period.

A further aspect of the present invention is directed to said method for measuring the expansion of aggregate material/slag samples wherein the percent expansion at each day is measured by dividing the difference between the daily dial gauge reading and the base reading or the final expansion is measured by dividing the difference between final dial gauge reading and the base reading by the initial specimen height and multiplying by 100.

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 drawings, wherein like numerals are used to refer to the same or similar elements:

BRIEF DESCRIPTION OF THE ACCOMPNAYING DRAWINGS

Figure 1: is a simplified schematic diagram of complete assembly of the test apparatus according to the present invention for determination of potential volume expansion of graded compacted slag aggregates when put in contact with heated or cooled water.

Figure 2: is a simplified schematic top view of the test apparatus.

Figure 3: is the cross-sectional view of the cylinder and piston assembly of the test apparatus, containing the slag dipped in the water and fixed to the displacement measurement device.

Figure 4: is the cross-sectional view of the cylinder with perforated bottom.

Figure 5: is the view of the perforated top/bottom plate used in the slag containing cylinder.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

This invention is directed to provide a test apparatus for measurement of expansion behavior specially but not exclusively of slags and a method of such testing and measurement. The slags expand when exposed to moisture due to presence of free CaO and MgO. Slags when intended to be used as construction aggregates must meet some physical property requirements specially the expansion which is required to be consistently below a given standard threshold. The measurement of the expansion is carried out using different standard procedures and set-up or apparatus which simulates the conditions of the intended application or as required by customer. In the present invention the set-up or apparatus has been designed, which is capable to measure the slag expansion (both long term and accelerated swelling) under conditions specified by different standards in a single set-up.

With reference to Figure 1, a simplified schematic view of complete assembly of the test apparatus according to the present invention for determination of potential volume expansion of graded compacted slag aggregates is shown which is having a bath container in the form of a double walled stainless steel chamber 19 having an insulator packing 20 in between capable of holding preferably water or any liquid 24 under pressurized and high temperature conditions. The apparatus 19 sits on bottom stands 23 and has a drainage valve 22 to drain off the water after the experiments.

Referring further to Figure 1, the apparatus is fixed with a solenoid based level sensor assembly and water inlet tube 21. This helps in maintaining a constant water level in the apparatus during the long experimental durations. In Figure 1, the heating element 25 is used to raise the temperature of the water to the desired value. Temperature sensor 12 is preferably positioned at the lower part of the apparatus in the wall opposite to the wall where the heating element 25 is fixed and provides a closed loop feedback to temperature controller and display 14 on the control and display panel 15 attached to the apparatus 19. Temperature sensor 12 is preferably a thermocouple 11, can be any type of temperature sensing device that can measure liquid temperatures continuously. The combination of heating element 25 and the temperature sensor 12 helps in maintaining constant temperatures in the apparatus during the experiments for long periods. Control of the water level and/or water temperature in this manner permits the addition of smaller amounts of water to the heating chambers continuously. This enables to maintain constant temperature profile. The apparatus is also fixed with a small stirrer 17 immersed into the bath and rotated using the motor 18 fixed vertically downwards.

With reference to Figure 1, a control and display panel 15 is attached to the apparatus and have temperature display screen 14, temperature adjusting knobs 13 and 16 for increasing and decreasing the temperatures respectively. It also has power on/off switch 26. The power switch 26 regulates the power to level sensors 21, heating element 25 and display screens 14.

Next in reference to Figure 2 that shows a simplified schematic top view of the test apparatus, the bath container i.e. the stainless steel chamber 19 has the two stainless steel slag containing cylinders/chambers 1 placed symmetrically through the openings on the top surface of the steel chamber 19.

Now referring to Figure 3 that shows the cross-sectional view of the cylinder and piston assembly of the test apparatus wherein the stainless steel slag containing chamber 1, having the perforated top plate 2 having a connecting rod 4 and a perforated bottom plate 3 fixed to the chamber 1. The connecting rod 4 is connected to the displacement measurement device 7 through a piston 5, connector 9 and the pivot 6. The displacement measurement device 7 is supported on the apparatus using a magnetic stand 8. When the volume of content/slag 10 in the chamber changes due to physical changes that occur during testing, the change is transmitted through the connecting rod 4 and is conveyed to the measurement device or gauge 7. The displacement measurement device 7 is capable of the measuring the displacement of the top plate 2 during the experiment with a wide range.

With continued reference to Figure 3, the top plate 2 rests on the contents of the chamber, which is slag 10, in use, and is free to move up and/or down in vertical direction. Typically, in use, a filter paper(not shown) is placed between the contents of the chamber 10 and the perforated plates to avoid the dispersion of the contents 10 in to the main apparatus 19.

Next with reference to Figure 4 that shows the cross-sectional view of the cylinder with perforated bottom, perforated bottom plate 3 is seen to be fixed to the chamber 1.

Referring to Figure 5, the perforated disc 3 comprises perforations extending in a series of concentric circles 1b, 1c, 1d and 1e about the centre 1a each having a diameter of 4 to 6mm preferably 5mm. This allows the water to freely pass through a slag sample, thereby minimizing the build-up of pressure within the slag chamber 1.

It would be thus apparent from the above description of a preferred embodiment of the test apparatus according to the present invention that the apparatus for expansion testing of slag samples, e.g. steel slag samples, comprises a bath container in the form of a double walled stainless steel chamber having an insulator packing in between which acts as the container capable of holding water/steam or any liquid under pressurized and high temperature conditions. The apparatus sits on four bottom stands and has a drainage valve connected to its bottom.

The main steel chamber/bath container has the provision to place two stainless slag containing cylinders/chambers symmetrically through the openings on the top surface of the primary steel chamber. The dimensions of the slag chamber being used of experiment varies based on the standard test to be carried out (i.e. diameter 210 mm in EN-1744, diameter 152.4 mm in ASTM – D4792, diameter 150 mm in IS-2720, diameter 150 mm in JIS-5015 etc). These chambers, have the perforated top plate having a connecting rod and a perforated bottom plate fixed to the chamber. The connecting rod is linked to the displacement measurement device through a piston rod. The displacement measurement device or the gauge supported on the apparatus using a magnetic stand. When the volume of content/slag in the chamber increases during testing, the change is transmitted through the connecting rod is conveyed to the measurement device or gauge. The displacement measurement device is capable of the measuring the displacement of the top plate during the experiment with a wide range. The top plate rests on the contents of the chamber, which is slag, in use, and is free to move up and/or down in vertical direction. Typically, in use, a filter paper is placed between the contents of the chamber and the perforated plates to avoid the dispersion of the contents into the main apparatus. The top and bottom perforated disc comprises perforations extending in a series of concentric circles about the centre hole each having a diameter of 5mm. This allows the water/steam to freely pass through a slag sample, thereby minimizing the pressure build-up.

The apparatus is fixed with a water inlet tube and solenoid based level sensor assembly. This helps in maintaining a constant water level in the apparatus during the long experimental durations. A heating element is fixed in immersed condition to raise the temperature of the water to the desired value or generate steam as and when required. Temperature sensor or thermocouple capable of measuring liquid/steam temperatures continuously is positioned at the lower part of the apparatus in the wall opposite to the side where the heating element is fixed. The thermocouple is connected in a closed loop feedback to temperature controller which controls the power to the heating element to maintain a constant set temperature. The temperature of the container is continuously displayed on the control and display panel attached to the apparatus. The control and display panel have temperature display screen, temperature adjusting knobs for setting the temperatures and power on/off switches which regulates the power to level sensors, heating element and display screens. The apparatus is also fixed with a small stirrer immersed into the bath and rotated using the motor fixed vertically downwards to maintain constant temperature throughout the container.

The objective of the invented apparatus is to hold a standard specified quantity of graded compacted slag aggregates in a standard specified size of chamber under the standard specified conditions (cold or heated water or steam) for a specified duration and measure the expansion. Preferred embodiments of the apparatus will carry out testing in compliance with European, Japanese and Indian standards.

In the experimental procedure, the representative slag sample are collected from the site and crushed (if required). The slags is then graded in to the sizes as specified in the standard (IS, JIS or EN etc) to be followed for the measurement of the expansion of the slag. To prepare the specimen the standard specified slag chamber is taken and a filter paper is spread over it. Graded slag samples are filled into the experimental chamber with a scoop and rammed in three equal layers one upon another using a tamping rod. The sample is filled to standard specified height (i.e. 125 mm in EN-1744, 116.43 mm in ASTM – D4792, 125 mm in IS-2720, 125 mm in JIS-5015 etc). A filter paper is placed over the rammed sample before placing the top perforated plated with connecting rod over it. The parent steel chamber is filled with water or steam as per the standard. The slag containing chambers are placed into the parent chamber either immersed in water or steam environment. A dial gauge or displacement measurement device is fixed to the connecting rod of the top plate using a pivot and the first reading of the gauge is recorded. The slag containing chamber is cured by keeping immersed in water or exposed to steam to a specified duration as per the followed testing standard (i.e. 120oC for 168 hrs in EN-1744, 70oC for 7 days in ASTM – D4792, 27oC for 96 hrs in IS-2720, 80oC for 6 hrs/day for 10 days in JIS-5015 etc). The readings of the dial gauge are recorded at regular intervals and at the end of the curing period. The slag is then discarded. The percent expansion at each day or the total expansion is measured by dividing the difference between the daily dial gauge reading and the base reading or final dial gauge reading and the base reading by the initial specimen height and multiplying by 100. The test is repeated for two or three specimens as specified by the standard followed.

The test apparatus according to the present invention is capable of measuring the expansion of two samples of slag simultaneously. However, if required/preferred for the apparatus to comprise more of testing units, as per the requirement of relevant standards, more chambers can be included in the same set-up. It has been found that the apparatus is capable of conducting tests suitable to many required standards and regulations for the use of slag as aggregates in civil constructions. The machine may be suitable for the testing of slag samples to ensure the standards required for alternative applications also. The apparatus according to the invention as described above may be suitable for testing the expansion of other solid materials also.