RICHMOND, CALIFORNIA, 94804

ATE MICROVISCOMETER (Shell Development Co. Design)

ASPHALT VISCOSITY joy defermining ASPHALT DURABILITY

DESCRIPTION The SLIDING PLATE MICROVISCOMETER combines the simplicity of the classical concept of viscosity-shearing a sample between hvwo parallel flat plates-with the sensitivity and accuracy of an electronic circuit for measuring movement. It is a precise and versatile instrument for determining viscosity in absolute units and is suitable for penetration- grade asphalts, liquid asphalts and other viscous mbterials. This MICRO- VISCOMETER has a range of one thousand to one hundred billion poise. At freezing temperatures this permits measuring the viscosity of all products from Grade 1 liquid asphalts to 40/50 penetration paving asphalts. At 77°F the range is from Grade 3 liquid asphalts to zere penetration paving asphalts. Since the shear rate may be accurately determined, it is equally applicable to materials having Newtonian or non-Newtonian flow properties.

The MICROVISCOMETER is designed for operation in constcmt-tem- perature water baths normally used for testing asphaltic materials. By using it in baths of different temperature, the viscosity-temperature char- acteristics of asphalt may be determined directly. The MICROVISCOMETER consists of hvo polished glass plates be- tween which is placed Q thin layer of the sample. This thin layer is made by pressing a warmed drop of the sample between the plates. The film thickness used in the MICROVISCOMETER normally is in the range from about 10 microns to 200 microns. Homogeneity of the film is determined by observing the uniformity of color in transmitted light. Thickness of the film is determined by weighing on cm analytical balance or by use of Model 1147 FILM FORMER. By means of quickly operated spring clamps, one of the glass plates is clamped to the MICROVISCOMETER Model 1113 frame and the other to the loading device. It is not necessary for the operator to put his hands in the water of the constant-temperature bath to do this. The sample will reach the test temperature within twwo minutes after being placed in the bath. The pulling force is applied through a simple balance beam pivoted on agate bearings and polished steel knife edges. This design permits extreme sensitivity while allowing a range in leads from 0.1 gram to 10 kilograms. An electronic circuit is used to follow the movement of the glass plate by controlling a simple servo motor. This drives an insulated micrometer and causes it to maintain a high resistance contact with a flag attached to the movable glass plate assembly. The effect of contact pressure in the following mechanism is unmeasurable ever the range of viscosities covered. Movement of the glass plate may be measured directly by reading the micrometer as a function of time, thus making the instrument complete by itself. For greater convenience, however, it has also been designed to per- mit recording the displacement of the glass plate on a millivolt recorder. This allows the operator to do other work while the test is in progress and provides a permrment graphical record of the test. Although any potentiometer type millivolt recorder with proper range may be used, the instrument generally has been used with a Varian Model G-10 Graphic Recorder modified by Hallikainen. With the recorder, 0.5 mm displacement of the glass plates is magnified to a 5-inch movement in the chart. Normally a movement of 0.1 mm is all that is needed for one viscosity determination. Measurements at four different shear rates can therefore be made in one chart width. If the movement is greater than this, the recording pen automatically moves to the other edge of the chart and continues its trace. Complete viscosity measurements of an 85/100 penetration asphalt may be made at four different shear rates at 77°F in less than fifteen minutes.

VISCOSITY-TEMPERATURE CHARACTERISTICS OF ASPHALT The SLIDING PLATE MICROVISCOMETER may be used in a constant-temperature bath at whatever temperature it is desired to measure viscosity. Since the viscosity in absolute units may be readily determined at two or more temperatures, it is an ideal instrument for measuring the viscosity-temperature characteristics of asphalt. The same ideniical sample may be run at different tempemtures. ASPHALT DURABILITY A method of measuring asphalt dumbility was described in the prize-winning paper "Microfilm Durability Test for Asphalt" by Griffin, Miles and Penther of Shell Development Company, PROCEEDINGS OF THE ASSOCIA- TION OF ASPHALT PAVING TECHNOLOGISTS, 24, p. 31, 1955.

microns thickness. The SLIDING PLATE MICROVISCOMETER is the instrument designed to measure viscosity in that test. The only additional equipment needed in making the microfilm durability test is a set of aging plates (available separately1 and an oven capable of maintaining a tempemtura of 225°F and equipped with a rotating shelf. CURING RATE OF CUTBACKS The curing rate of all types of cutbacks and slow-curing road oils may be determined by exposing a thin film of materia'l at a selected temperature and measuring increase in viscosity with time. MEASURING THE VISCOSITY OF ASPHALT IN A PAVEMENT Since only a very small quantity of asphalt Is needed for a viscosity measurement, it is possible to simplify the method of asphalt recovery from a pavement. After dissolving a small section of pavement in benzene, a por- tion of the extract is centrifuged, a gloss plate is dipped in the extract, and the solvent is evapomted in an ineti atmosphere in the dark at room tempemture. The asphalt is then scraped off the glass plate and placed on the viscosity plates for the usual viscosity measurement. -,

VISCOSITY OF RESINS, PLASTICS EL OTHER VISCOUS MATERIALS The instrument may be used for measuring the viscosity of resins, plastics and other viscous materials which will adhere to the glass sample plates. Uniformity of thickness of thick films which are not tmnspurent may be checked by use of a dial comparator or by use of Model 1147 FILM FORMER.

SPECIFICATIONS

SLIDING PLATE MICROVISCOMETER The MICROVISCOMETER is a precision instrument designed both for routine operation and research use. All metol ports which go in the water are nickel-plated or made of stainless steel. The complete electronic circuit and servo motor is housed in the box at the top of the stand and is fused for safety. Overall height of the instrument is 21 inches. The micrometer on the instrument is graduated in millimeters and reads directly in microns. A mngo adjust- ment is provided on the face plate of the MICROVISCOMETER so that each division on the recording chart will cor- respond exactty to a 5 micron movement of the glass plate. This facilitates calculation of viscosity by meonr of Q nomogmph which is included with complete operating instructions. The MICROVISCOMETER is supplied with one pair of viscosity plates, a set of weights from 1 to loo0 grams; for 115 volt, 60 cycle AC. For 220 volt an external transformer is supplied. Can be used at 50 cycle without modification. SLIDING PLATE MICROVISCOMEKR ACCESSORIES -- VISCOSITY PLATES-lU-403 AGING PLATES-lU-404 The viscosity plates ore mode The aging plates for use in mak- of polish ed flat Pyrex glass, 20 ing the microfilm dumbility test for mwi by 30 mm in sire and 0.240. asphalt ore made of polished flat inch thick with squared edges. Pyrex glass, 40 mm by 40 mm in They ore supplied in matched size and 0.240-inch thick with pairs. squared edges. They ore supplied WATER BATH-MODEL 1141 in matched pairs.

This both has been specifically designed for the MICROVISCOMETER. It con- sists of two gloss jars, one within the other. The inner iar has a capacity of 2% gallons. The top of the bath is mode of Bakelite with a cut-out large enough to permit insertion of the MICROVISCOMETER in the bath. The MICROVISCOMETER rests on a stainless steel plate. Suspended from the Bakelite top is on electrical heating unit and a cooling coil. A motor-driven stirrer equipped with on impeller is mounted on the Bokelite top. The bath is designed os standard equipment for opemtion at 115 volts 60 cycles AC; modification can be mode for other power supplies at extm charge.

TEMPERATURE CONTROL FOR WATER BATH

We recommend for tempemture control of the vmter bath either a Hallikainen-Shell THERMOTROL Temperature Controller or o Hollikainen- Shell RESISTOTROL Temperature Controller. The selection of either one would depend upon the degree of accuracy desired. The THERMOTROL incorporates proportional and reset control features, thereby providing for much closer bath temper&we control than might be obtained by the RESISTOTROL Temperature Controller. The RESISTOTROL incorporates "on- off" coiltrol only.

The THERMOTROL is capable of controlling the water bath to &.Ol'C. and the RESISTOTROL to &.1X. With either of these controllen, a Halli- kainen Model 1060 Resistonce Themometer would be used os the pri- mary element in the water both.

For derails on the THERMOTROL or RESISTOTROL, ask for the bra. chums describing and illustmting each of these instruments.

VARIAN o-10 RECORDER

Vorian Model G-10 Graphic Recorder is an all-purpose portable labom- tory millivolt recorder. For use with the MICROVISCOMETER it is furnished with one roll of chart paper. For convenience, the standard Varian recorder is modified by Hallikainen Instruments.

Standard instrument is for operation at 115 volt, 60 cycle; can be sup- plied for other voltages and frequencies at extra charge.

FILM FORMER-MODEL 1147

The FILM FORMER has been developed to eliminate the need for weighing samples to assure uniform thickness. The FllM FORMER consists of a base with (I flat ground surface onto which is placed an adjustable weight with a ground surface. The viscosity plates are placed behveen these ground surfaces. In op- emtion. one of the viscosity plates is placed on the base and a thickness gauge corresponding to the thickness of the sample desired is placed upon it. Over the thickness gauge is placed the second glass plate. The weight is then set upon the base so that its ground face is in contact with the upper glass plate. With the ground face of the weight in contact with the gloss plate, the legs of the weight must rest on the base, and if they do not, then the adjustment of the weight is made to permit the legs to touch the base. The weight, upper gloss plate, and thickness gauge are then nmoved. The sample is applied to the lower glass plate. The upper glass plate is placed on the sample and the weight is replaced on the base. As the weight descends, it forces excess som- ple from between the plates so that when the weight has dropped into place, the proper amount is left between the glass plates. The adiustobility of the legs on the weight make it possible to apply thicknesses of samples over Q wide mnge. The FILM FORMER is manufactured of stainless steel.

SLIDE RULR-MODEL 1149

To eliminate the need for referring to nomogmphs and the need for calculation of mathematical equations, Model 1149 SLIDE RULE has been developed with the co- operation of Shell Development Company. The SLIDE RULE is of the usual type except for the scales which me provided for special use with the MICROVISCOMETER. Data obtained in a test involving the slope or angle of a curve on the chart of the recorder, the film thickness, and the amount of weights used are applied to the proper scales on the slide rule and the answer in viscosity (poise) is readily obtained.

SPECIAL HEAVY WEIGHTS-1 TO 10 KG.

The set of weights supplied with the MICROVISCOMETER as standard equipment range from a minimum individual weight of 1 gram to a maximum individual weight of SD0 gmms with the entire set totolllng 1100 gmms. For measuring as- phalts with viscosities mnging considembly higher than those which the standard set will accommodate, we have designed special weights as illustrated at the left. These are 1ODD. 2DDD, and 5DDO gram weights with the maximum t&d to be applied to the instrument restricted to 10,000 grams. These special heavy weights with their weight hanger ore available at on extm charge.