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(this was a research paper assignment in a graduate course on Material Durability)

DETERMINATION OF CAPILLARITY AND PORE SIZE INTERRELATIONSHIP AND THEIR EFFECT ON DURABILITY OF POROUS MATERIAL

ABSTRACT

The function of this paper is to provide both a library research and a laboratory testing program that will help explain the determination of capillarity and pore size interrelationships and their effect on durability of porous materials.    Most porosity measurements provide results that are dependant on the test method employed. Porosity can be measured using specific gravity methods, absorption tests, microscopy, mercury porosimetry, or through capillarity determinations.  Most authorities agree that the durability of a material is directly related to the type of porosity within the material. The actual mode of failure of a "frost sensitive" material is still much debated, however, Dunn and Hudec (1972) appears to have the most plausible hypothesis. A laboratory investigation was carried out to attempt to develop a "quick and easy" test procedure that will provide information about pore size and pore size distribution within an aggregate. The test method utilizing apparent specific gravity determinations proved unsuccessful since a material segregation occurred during the crushing process. The test method utilizing time dependant absorption provided informative data concerning the relative porosity of the aggregate samples.  An untried test method has been developed which may provide quantitative data for total effective porosity, capillarity, and pore size distribution.

INTRODUCTION

The purpose of this paper is to present a discussion of the various aspects of porosity and capillarity as it pertains to the durability of porous materials. In addition, n laboratory testing program was set up to determine a "quick and easy" way of evaluating porosity and capillarity.

It has long been known that the weathering process of construction materials involves water in one form or another. The problem of predicting the durability of a product is, in part, due to the lack of complete understanding toward the mechanism of the weathering process.

The durability of environmentally exposed building products such as stone, brick, and concrete, is dependant on the material's behavior when exposed to differing moisture conditions. Lewis et al (1953) states that the most controlling physical property of a building material, with respect to durability, is its porosity, pore-size distribution, and capillarity; capillarity is dependant, in part, on pore-size distribution.

QUANTIFYING POROSITY

The porosity of a material can be expressed in various forms. The definition of total porosity can be expressed either as a ratio of the void volume to the bulk volume of the material, or as a ratio of the void volume to the solid volume. The first ratio is generally referred to as porosity; the latter ratio is referred to as voids ratio.

Measurement of the true total porosity is difficult. Most testing procedures which claim to evaluate total porosity, in fact only measure the effective porosity for various condition.  The most frequently used method for determining the total porosity of aggregates involve the determination of specific gravity using pycnometry. The value of porosity obtained will depend on the pycnometic fluid used in the testing. Some voids, even in comminuted samples, have entrances that are too small for water, carbon tetrachloride, nitrogen, helium, or other pycnometric fluids to enter into the larger pores. Thus most porosity determinations are actually effective porosities under standardized testing conditions.

The effective porosity of a material is a ratio measure of the volume of all voids permeable to the pycnometric fluid, compared to the value of the solid plus those voids impermeable to the pycnometric fluid. Here too, the. value of effective porosity will vary with pycnometric fluid type and environmental conditions such as temperature and pressure.

 Litvan (1984) has shown that very high and very low total or effective porosity of building materials generally have good service records. The problem lies with material of intermediate status. In addition, the introduction of porosity into a building material such as concrete, increases the durability of the material substantially. This apparent inconsistency requires an examination of the type of porosity observed in porous construction materials.

Type of Porosity

Verbeck & Landgren (1960), Litvan (1984), Neville (1981) and others have indicated that the amount of porosity is not critical for the evaluation of durability; although porosity distribution is paramount. A concentration of small diameter pores will give material a higher internal surface area than will a concentration of larger diameter pores. In addition, water will perform differently within different sized pores.

MECHANISMS OF DETERIORATION OF "FROST SUSCEPTIBLE" MATERIALS

Currently, the mechanics of destructive properties of water within pores of differing sizes are not universally accepted.

Verbeck and Landgren (1960) associates durability of concrete and concrete aggregate with the time required to attain a critical degree of saturation. This is a function of capillarity of both the cement paste and the concrete aggregate; which, in turn, is a function of the pore size distribution and type of pore-interconnection.

ACI Committee 201 (1977) presents Powers' early assessment of "frost damage" in cement pastes. Powers attributed frost damage in cement pastes to hydraulic pressures within the pore system. This pore pressure is generated by the size of pores and their interconnections i.e. pore distribution. When ice forms, according to Powers, the volume increases due to the formation of the ice crystals causes hydraulic pressures within the surrounding water. If permeability of the paste or aggregate is high then the hydraulic pressure is quickly dissipated through the movement of water away from the centre of ice formation. However, if pore-size distribution and capillarity are such that the over-all permeability is low then sufficient hydraulic pressures may be generated which will fail the paste and/or aggregate.

Additional work by Powers and Helmuth revealed that water actually flowed toward the point of freezing; this is in direct contrast with the above outlined mechanism in the hydraulic pressure theory. Power's revised hypothesis associates the failure mechanism with ice accretion. During the initial steps of ice formation, the normally weak concentration of alkalies within the pore water increases in concentration around the ice crystal. The action of osmosis attracts water from capillary pores toward the site of freezing. Ice accretes and the dilation pressure of the ice acting on the pore walls cause disruption of the paste and/or aggregate.

Litvan (1984) states that "frost action" also occurs with organic liquids that contract on freezing; this is in contrast with the hydraulic pressure theory. Feldman and Beaudoin (1978) show that expansion of porous glass occurs when wetted with methanol, carbon tetrachloride, and water; this is in contrast with Powers' revised osmotic hypothesis.

Dunn and Hudec (1972) agree with Verbeck and Landgren (1960) that pore size and pore size distribution play a major role in "frost sensitive" porous material. However, Dunn and Hudec (1972) hypothesize a different mechanism of failure. It was shown that many "frost sensitive" carbonate rocks had little or no ice formation within them when the rock pieces were saturated and cooled from ambient temperature to temperatures of -200C and -400 C. These failed rocks are not considered "frost sensitive" but are considered "sorption sensitive", even though the resulting destruction is indistinguishable in character. Sorption sensitive rocks may deteriorate when in contact with water by warming and cooling, by wetting and drying, or even by humidity changes alone.

Dunn and Hudec (1972) state that the mechanism of sorption effects a reduction of surface tension of the adsorbent. The amount of surface tension held within the solid is dependant on the amount of internal surface area within a porous material. When surface tension of the solid is reduced through the adsorption of water, elastic expansion proportional with the stress reduction will occur. Hudec (1986 per. comm.) stated that the behavior of an aggregate piece on immersion is dependant on the dominant pore size. If the dominant pore size is in a capillary-size range, the solid will be affected by the tension in the capillary, leading to aggregate contraction. When the capillary tension is gone, i.e. when the pores are filled, the rock will "relax" to approximately the original dimension. If the pore size is large, then immersion in a fluid will not make a difference on volume stability. If the dominant pore size is very fine, as in micropores, only adsorbed water will form. The adsorbed water has a lower vapour pressure than the vapour pressure required to fill capillaries. If low vapour pressure water (adsorbed water) is in contact with water of a high vapour water (bulk water) there will be a tendency of high vapour pressure water to travel to the lower vapour pressure site. This will result in positive pressure on the walls of the micropores, thereby tending to expand the rock. The rock will continue to expand until the vapour pressures are equalized or until the allowable elastic deformation of the rock resists the expansive force or until the rock piece fails.

Dunn and Hudec (1972) state that the unfrozen water within their test specimens, at -200C and -400 C, is largely in the form of adsorbed water.

The observed "frost susceptibility" of concrete due to the coarse aggregate component can result from failure either due to ice formation or due to the sorption characteristics of the aggregate piece.

The application of de-icing salts on concrete roadways support Dunn and Hudec's hypothesis of sorption sensitivity. Deicers reduce the freezing point of water, thereby reducing the number of potential freeze-thaw cycles, and yet scaling and pop-outs on salt applied concretes are more severe than non-salted concretes.

Litvan (1972) proposed a variation of Dunn and Hudec's (1972) hypothesis as applied to cement paste where micropores are present in conjunction with capillary and larger pores. Litvan states that bulk ice has a lower vapour pressure then the adsorbed water. The vapour pressure difference will cause a migration of water to locations where it is able to freeze such as in the larger pores. This process leads to partial desiccation of the paste and accumulation of ice in crevices (ACI C201). Failure occurs when the redistributed moisture has to travel long paths, or freezing time is rapid, or there is too much water. If failure occurs, Litvan believes that the water is in a semi-amorphous solid state, not in the form of ice crystals.

Litvan (1984) re-affirms his conclusion from 1972 that supercooled adsorbed water cannot extert a hydraulic pressure on micropore walls. Litvan states that ice will form in large pores "drawing" water from the micropores to the ice, due to the vapour pressure differences. This may be true for cement paste with a sufficient number and distributions of large pores to accomodate the ice formation. However, with respect to aggregate containing a majority of the pore size in the range of capillary or micropore size, Dunn and Hudec's (1974) hypothesis for the mechanism of "frost action" remains plausible since ice cannot form in these pores.

 

MEASUREMENT OF POROSITY AND CAPILLARITY

Although the actual mechanism for failure of a porous system has not been universally accepted, most authorities agree that pore size and pore size distribution within the porous material will reveal the potential durability of a product under different weathering conditions.

If "frost susceptible" material undergoes sufficient summertime drying such that critical saturation cannot be achieved in the wet and/or cold seasons, then aggregates will not behave deleteriously even if the aggregate is deemed "frost sensitive" on wetting and drying, freezing and thawing, or warming and cooling. Thus, not only is the porosity important but the transmissibility of water or the capillarity of the porous system is critical to the durability of a porous material.

Since the pore system of a material, if known, will provide valuable data concerning the durability of a material, tests to determine various porosity features must be accurate, even if test precision is unattainable.

Specific gravity of a solid, when compared to the bulk specific gravity will provide a measure of porosity. To calculate total porosity, the measured sample must be ground sufficiently fine so as to expose all entrapped voids. As mentioned previously, true specific gravity of a solid is determined pycnometrically. Feldman (1984) utilized methanol and helium as pycnometric fluids to evaluate porosity of blended cements. A different value of total porosity may be measured, depending on the molecular size of the pycnometric fluid. Feldman did not use water since chemical and structural instability of portland cement systems are jeopardized when subject to low relative humidities within the pores. Sereda et al (1980) states that when dried hydrated portland cement paste is exposed to water vapour, the water molecules enter the pores and adsorb onto the solid that surrounds the pores. Some water molecules penetrate into the layered calcium silicate structure within the solid. The solid particles swell because of interlayer penetration coupled with the physical interaction of water on the surface of the solid. This is called Bangham swelling and is due to a decrease in surface tension forces that compress the solid.

More commonly, effective porosity is measured rather than total porosity. Absorption tests measure effective porosity under various saturation, temperature, and pressure conditions. The type of absorption tests available have variable absorbates (i.e. water, methanol, carbon tetrachloride or other organic solvents); variable temperature (i.e. 200 C, 1000C boiling); and variable pressures (i.e. ambient pressures, vacuum saturations). Microscopy can also be used to determine the total or effective porosity, however this is a long and tedious process which is dependant on the resolution of the microscope.

Feldman (1983) used three methods for the determination of porosity in hydrated blended cement pastes. The first sample was D-dried and subsequently saturated with methanol. The samples were then damp dried and the mass was determined in air and again submerged in methanol. The second method of porosity determination involved D-dried specimens subject to helium comparison pycnometry. The third method Feldman used is mercury porosimetry. The volume of mercury intruded at the maximum pressure was considered to be the total porosity.

The above tests are used for determining various types of total porosity, however, the pore size distribution of a material will govern the material's potential durability under differing environmental conditions.

The microscope will differentiate between pore size up to the instrument's resolution limit. This method can therefore provide an effective pore size as well as given an approximation of pore size distribution.

Another method which provide a measure of pore size is based on capillarity of the specimen. Machen et al (1960) developed a rapid test to determine the average pore size of a material based on capillarity. A relatively small piece of porous material, i.e. less than 10 mm, is lowered to a liquid surface, usually water. The time is measured from the instant the liquid wets the lower surface until the liquid reaches the top of the specimen. The effective pore radius can then be calculated based on the rate of capillary rise.

Shaw et al (1963), while investigating pore size and pore size distribution of inorganic calalysts and catalytic support systems, have concluded that nitrogen adsorption and desorption techniques provided reliable data for pore systems with an average diameter of 5 nm or less. Shaw et al (1963) demonstrates that porosimetry by high-pressure mercury injection offers a test that is quick, simple, and reliable. The mercury injection method is capable of pore measurements varying between 100 um to 1.7 nm when mercury pressures are varied between 170 KPa to 210 MPa respectively.

The earlier mercury instruments measured a minimum pore size of 10 nm since a maximum mercury pressure of only 70 MPa was available, hence all pores with entrances less than 10 nm went unmeasured. With the development of stronger mercury apparatus, the minimum detectable pore size was reduced to 1.7 nm, however, certain problems subsequently arose.

Beaudoin (1979) and Feldman (1983 and 1984) revealed that the density of the solid portion of a porous material as measured by helium pycnometry is less when compared with that measured by mercury intrusion. The mercury seems to reach pore structures that the methanol cannot reach. As mentioned previously, the lower pore size limit by mercury intrusion is approximately 2 nm. The molecular diameter of methanol is 0.42 nm, much less than the minimum size limit of the mercury.  Beaudoin (1979) and Feldman (1983 and 1984) both conclude that the mercury must be capable of breaking through some pore structures with entrances of less than 0.42 nm in diameter.  Microstructural damage first occurs between 70 MPa and 100 MPa of pressure.  Feldman (1984) further concludes that mercury intrusion curves may not represent the true pore size distribution of the investigated material. To determine whether or not microstrucural damage has occurred, Feldman (1984) suggests that the mercury injected sample be distilled free of mercury and retested. The distillation process at 1050C will take between 24 hours and 360 hours to return the sample to near its original mass.

Beaudoin (1979) suggests that porosity measurements of some hydrated cementitious systems by high pressure mercury intrusion may have microstructural limitations. These limitations may include:

1) complete filling of pore space with mercury may not actually occur even though it is conventionally assumed;

2) structural damage of the relatively weak walls of discrete pores and subsequent entry of mercury into these pores;

3) exclusion or entry of mercury from or into trapped space between aggregations of layered silicates;

4) exclusion of mercury from pores or pore entrances which are too small for mercury to penetrate at a maximum intrusion pressure of 410 MPa; 5) blocked pore space due to the presence of an interfering phase i.e. crystalized salt; and

6) changes in contact angle between mercury and the solid surface.

Lewis et al (1953) outlines the use of the Poiseuille equation to calculate the average size of pores in a sample. Lewis also states that for extremely small pores the variation in accessibility to various sized molecules can be measured. For pores in a larger size range, the variation in absorption of liquids of different penetrating abilities will give a rough estimate of pore size. Capillarity of rocks have been studied almost exclusively in conjunction with reservoir rocks in the petroleum industry. Capillarity and the interrelationships with pore size and pore size distribution of porous construction materials is the key to understanding durability of these materials Verbeck and Landgren (1960), Dunn and Hudec (1972) and others. 

The capillary diaphram apparatus is the most direct method to measure the capillary pressure in small core samples. A column of water is suspended beneath a porous diaphram upon which a fully saturated core is in contact. the suspended water provides a suction at the base of the sample. The degree of saturation of the sample is measured at various suction values which allows calculation of capillarity.

The earliest measurements of capillary pressure <Hassler et al (1944)> were made by allowing a column of sand saturated with liquid to come to equilibrium by gravity drainage and subsequently determining the saturation of samples taken from locations throughout the column. This method cannot be applied to rocks since the height of the rock sample would be too high for all practical purposes. In order to decrease the height of rock required, the force of gravity must be increased. Hassler et al (1944) developed a centrifuge that will simulate accelerations several thousand times that of gravity. The degree of saturation of a sample at various g-forces can be calculated from the amount of water extracted during the spinning process.

LABORATORY INVESTIGATION

The function of the laboratory testing program was to attempt a "quick and easy" method of evaluating the capillarity and pore size interrelationships for two distinctive concrete coarse aggregate samples.

The scope of this work was to determine the amount and size distribution of the water impermeable voids within the aggregate pieces. In addition, separate subsamples of the respective concrete stones were subject to a time dependant absorption test in order to ascertain the capillary characteristics of the materials.

Sample "G" was obtained from a natural pit-run quarry outside the London, Ontario Area and contains a variety of igneous, metamorphic and sedimentary particles (Enclosure 1). Sample "L" was obtained from a ready mix concrete supplier and is composed of a grey muddy to shaley crushed limestone.

Pore Size Distribution

The pore size distribution portion of the testing program involved the crushing and separation of various size fractions. Each of the size fractions were tested for apparent specific gravity. The apparent specific gravity of each size fraction would reveal progressively smaller and smaller impermeable voids. Exposure of the impermeable voids would lead to an increase in apparent specific gravity with decreased grain size.

The total amount of "exposed" porosity could be determined from a comparison of the apparent specific gravity of the large aggregate to the apparent specific gravity of the smallest size fraction, as shown in the following:

where:

PT = 1 - GL/GS

PT = total percentage porosity of the impermeable voids; GL = apparent specific gravity of largest size material; GS = apparent specific gravity of smallest size material.

To determine the proportions of voids exposed between successive aggregate grain sizes, the respective apparent specific gravities must be compared, as shown in the following.

P i_1      = 1 - Gi/Gi-1

where:

P i-1 is the amount of porosity exposed between successive grain size fractions.

Gi    is the apparent specific gravity of the coarser size f raction.

G i-1 is the apparent specific gravity of the next size fraction smaller than Gi.

 

The data concerning total porosity of impermeable voids and the proportion of impermeable voids released between size fractions will now be known and the impermeable pore size distribution can be assessed.

Discussion of Test

The gradational apparent specific gravity determination will not reveal an actual pore size distribution but will provide a relative distribution of voids exposed between size fractions. The actual average pore diameter exposed will be a much smaller fraction of the nominal aggregate size.

Test Procedure and Results

The samples were obtained in the size range of 19.0 mm to 9.5 mm. To obtain the size fractions required a size reduction process was necessary. The samples were reduced to the desired size fraction by crushing in a Proctor test mould. A 100 g sample was placed in the mould and struck 50 times with a Standard Proctor hammer. After the fifty blows, the sample was passed through a set of sieves and the remaining large over-sized material was again processed with the Proctor device.

To pass the entire 100 g sample into the network of sieve, three returns to the Proctor device was required. This crushing procedure was repeated in 100 g increments until the required amount of material from each size fraction was obtained.

After sample preparation, the mass in air and mass submerged in water of the samples were determined. Prior to the determination of the submerged mass, the samples were vacuumed saturated at -95 KPa in water at 400C for a period of twenty minutes.

The following table presents the apparent specific gravity determination of the various size fractions for the pit-run gravel (G) and the crushed

limestone (L).

 

Apparent  Specific Gravity

 

Size Range

Sample 'G'

Sample 'L'

19.0 mm to

12.5 mm

2.711

2.736

12.5 mm to

9.5 mm

2.708

2.777

9.5 mm to

4.75 mm

2.709

2.778

4.75 mm to

2.36 mm

2.692

2.770

2.36 mm to

1.19 mm

2.677

2.747

1.19 mm to

600 um

2.661

2.725

600 um to

300 um

2.673

2.704

300 um to

150 um

2.645

2.729

150 um to

75 um

2.685

2.725

75 um to

53 um

2.620

2.761

53 um to

0

2.531

2.596

Discussion of Results

The general trend of the apparent specific gravities for the size fractions tested is opposite to that expected. A possible explanation of the results is that during the crushing process, a segregation of materials occurred. One method of beneficiating a rock quarry would be to pass the material through a crushing program; the crusher tends to eliminate the deleterious materials through the production of fines. This appears to be the case for this test procedure.

Capillarity

The capillarity of the two subject crushed stone samples was qualitatively assessed through a time dependant absorption program. The degree and rate of saturation of the samples were determined. The capillarity data can be used to relatively rank the effective pore size and the pore size distribution of the rock sample.

 

Test Procedure and Results

Ten sub-samples were taken from each aggregate type. The sizing of the samples was controlled such that all material passed the 19 mm sieve and was retained on the 9.5 mm sieve prior to the start of the test. The aggregate was oven dried at 1050C for a period of four hours and allowed to cool in an enclosed container.

The samples were isolated and flooded for a predetermined time period. At the designated time limit, the samples were drained then surface dried. The mass of the saturated surface dried material was recorded. The samples were then re-flooded and allowed to soak for a total of 24 hours. After the 24 hour total soaking time had elapsed, the samples were again surface dried and masses were recorded. The samples were then oven dried at 1050C for a period of 24 hours. The dry mass of the samples was recorded.

The following table presents the time dependant absorption value, the 24 hours absorption value and the time dependant degree of saturation for each of the samples tested:

Time = t

% Absorption

at t

% Absorption

24 hrs

Degree of

Saturation at t

Sample 'G'

 

 

 

5 min

0.70

1.10

63.2

10 min

1.11

1.51

73.9

20 min

0.92

1.24

74.4

40 min

0.90

1.07

84.6

1 hr

1.24

1.37

90.7

1.5 hr

1.14

1.19

95.9

2.0 hr

1.01

1.04

96.9

8.5 hr

1.21

1.24

97.3

12.5 hr

1.04

1.05

98.5

24 hr

1.31

1.31

100.0

 

Time = t

Absorption at t

% Absorption

24 hrs

Degree of

Saturation at t

Sample 'L'

 

 

 

5 min

0.70

1.38

50.7

10 min

0.78

1.35

58.0

20 min

0.91

1.35

67.7

40 min

1.19

1.48

80.6

1 hr

1.25

1.46

86.1

1.5 hr

1.31

1.43

91.7

2.0 hr

1.30

1.38

94.3

8.5 hr

1.41

N/A

N/A

12.5 hr

2.52

2.52

N/A

24 hr

1.47

1.47

100.0

5.2.2 Discussion of Results

This test was successful in attempting to determine the relative effective pore size and capillarity of the two aggregate samples. Sample 'G' attained a higher degree of saturation for a given time period, however the rate of saturation for Sample 'L' was much greater and the degree of saturation approximately equalized after a period of two hours.

Interpretation of these results is subjective and should be verified by more conventional means. The 24 hour absorption tests indicate that the limestone aggregate has a higher total effective porosity than the pit run gravel. The initial saturation at t = 5 min indicate that the effective pore diameter is smaller in the pit run gravel than the limestone aggregate.

The rate of water uptake in both Samples 'G' and 'L' indicate that the porosity has a well sorted distribution, with a concentration of fine pores in Sample 'G' and a concentration of a larger capillary pores in Sample 'L'.

CONCLUSION

The laboratory program has revealed that the method of apparent specific gravity determination for the evaluation of inaccessible void content and distribution is not valid.

The capillarity tests utilizing time dependant degree of saturation reveals some useful information concerning the relative pore size and pore size distribution. This test should be carried out a step further to determine repeatability and correlation with conventional testing techniques.

RECOMMENDATIONS

During the performance of the apparent specific gravity tests and the time dependant absorption tests, evolution of minute bubbles were observed. Machin, Parsons, and Montgomery (1960) developed some rapid test methods for the determination of the approximate average pore radius, total pore value, and surface area contained in porous materials. Based on an extension of these test methods, the following test procedure may produce informative data concerning the porosity of porous materials.

bullet

1)Oven dry a suitable quantity of the subject material.

bullet

2)Determine the 5 minute absorption and degree of saturation of the aggregate.

bullet

3)Determine the 24 hour absorption of the aggregate.

bullet

4)Place dry sample in a pycnometer of suitable capacity and construction (Enclosure 2)

bullet

5)Quickly introduce de-aired distilled water. Start stop watch.

bullet

6)Gently agitate and vibrate periodically during the initial five minutes.

bullet

7)After a five minute period add de-aired distilled water to fill the tube to the pycnometer's calibration mark.

bullet

8)At pre-determined time intervals, measure the water level in the pycnometer. Prior to water level measurement, gently agitate the material in the pycnometer to release trapped air below an aggregate piece.

bullet

9)After bubble evolution has stopped, transfer the pycnometer apparatus into a vacuum cell.

bullet

10)Place a second pycnometer in the vacuum cell filled only with de-aired distilled water.

bullet

11)Evacuate the vacuum cell. Record vacuum pressure and water level of both pycnometers after gentle agitation (vibrate the cell). These values should also be recorded on a predetermined periodic basis.

bullet

12)Stop the tests after bubble evolution has ceased. Record the water level in both pycnometers at atmospheric pressure.

From the data obtained in the above outlined procedure, a quantitative analysis of total porosity, degree of saturation, rate of saturation, and pore size distribution can be calculated.

REFERENCES

1.       ACI Committee 201 (1977) "Guide to Durable Concrete" ACI Journal, Title No. 74-53 pp 573-609

2.       Beaudoin, J.J. (1979) "Porosity Measurements of Some Hydrated Cementitious Systems by High Pressure Mercury Intrusion - Microstructural Limitations". Cement and Concrete Research, vol. 9 No. 6 pp 771-781. National Research Council of Canada DBR 868

3.       Dunn J.R.; Hudec, P.P. (1972) "Frost and Sorption Effects in Argillaceous Rocks". Frost Action in Soils; Highway Research Record No. 393, Highway Research Board pp 65-78

4.        Feldman, R.F. (1984) "Pore Structure Damage in Blended Cements by Mercury    Intrusion". Jour. Amer. Cer. Soc., Vol. 67 No. 1

5.     Feldman, R.F. (1983) "Significance of Porosity Measurements on Blended Cement Performance". Proc of CANMET/ACI First International Conference on the Use of Fly Ash, Silica Fume, Slag and other Mineral By-Products in Concrete. Vol. 1, SP-79 pp 415-433. National Research Council of Canada DBR 1207.

6      Feldman, R.F.; Beaudoin, J.J. (1978) "Some Factors Affecting Durability of Sulphur-Impregnated Porous Bodies". Cement and Concrete Research Vol. 8 No. 3 pp 273-282. National Research Council of Canada DBR 780

7.     Hassler, G.L.; Brunner, E. (1945) "Measurement of Capillary Pressures in Small Core Samples". Transactions, Am. Inst. Mining Metallurgical Engrs., Vol. 160 pp 114-223

8.     Hudec, P.P., personal communications

 9.     Lambe, T.W. (1951) "Soil Testing for Engineers". John Wiley & Sons

10. Lewis, D.W.; Dolch, W.L.; and Woods, K.B. (1953) "Porosity Determinations and the Significance of Pore Characteristics of Aggregates." Proceedings, ASTM Vol. 53 pp 949-958

11.   Litvan, G.G. (1984) "Frost Action in Porous Systems". Seminaire: Durabilite des Beton et des Pierres Seminaire Organise avec la Collaboration de 1'UNESCO par le College International des Sciences de la Construction. pp 95-108. National Research Council of Canada DBR 1176

12.   Machin, W.D.; Parsons, B.I.; and Montgomery, D.S. (1960) "Rapid Test Methods for Determination of the Approximate Average Pore Radius, Total Pore Volume, and Surface Area Contained in Porous Materials".

Department of Mines and Technical Surveys, Ottawa, Technical Bulletin No. 16

13. Sereda, P.J.; Feldman, R.F.; Ramachandran, V.S. (1980) "Porosity and Pore Size Distribution in Ordinary Portland Cement Paste". 7th Int. Congress on the Chemistry of Cement, Vol. 1, Paris pp VI-1/10-VI-1/21. National

Research Council of Canada DBR 977

14. Shaw, G.T.; Parsons, B.I.; and Montgomery, D.S. (1963) "Porosity by Mercury Injection". Department of Mines and Technical Surveys, Ottawa, Technical Bulletin No. 45

15. Verbeck, G.; Landgren, R. (1960) "Influence of Physical Characteristics of Aggregates on Frost Resistance of Concrete". Proceedings, ASTM Vol. 60, pp 1063-1079

horizontal rule

PETROGRAPHIC ANALYSIS OF SAMPLE "G"

 

LITHOLOGIC DESCRIPTION

MTC Type

Weight

Percent

 

 

g

of total

CARBONATES - hard,grey,white,tan

1

394.0

65.7

CARBONATES - sandy,hard,grey,lt.brown

2

35.6

5.9

CARBONATES - sandy,medium hard,lt.brown

21

4.6

0.8

SANDSTONE - hard,brown

3

27.0

4.5

GNEISS-SCHIST - hard

4

18.4

3.1

QUARTZITE - coarse & fine grained,white

5

2.6

-0.4

ARGILLITE - hard,green

6

6.4

1.1

GRANITE-DIORITE-GABBRO - 40%/30%/30I

8

21.4

3.6

CARBONATES - sandy,soft,pitted,lt.brn,grey

41

11.6

1.9

CHERT-CHERTY CARBONATES - white,tan

26

35.6

5.9

ENCRUSTATION - calcium carbonate

52

1.8

0.3

SANDSTONE - brittle,brown

30

10.3

1.7

CHERT-CHERTY CARBONATES - white,tan,leache

45

8.2

1.4

SANDSTONE - friable,brown

46

13.2

2.2

CEMENTATIONS - calcium carbonate

53

0.4

0.1

SHALE - clayey,very soft,brown,red

61

8.8

1.5

Reference

Standard:

MTC Form PH-CC-343

83-6

 

 

 

 

 

 

Percent Good -----------

85.9

 

 

 

Percent Fair...........

9.9

Percent Crushed..

0

 

Percent Poor..........

3.6

 

 

 

 

 

Percent Flat

 

 

Percent Deleterious....

1.5

and Elongate.....

10

 

               

PETROGRAPHIC NUMBER

Hot Mix, Surface Treatment,and Concrete......... 151

horizontal rule

P.P. Hudec, PhD, Professor Emeritus, University of Windsor

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Copyright by Peter P. Hudec.   May be excerpted for educational use.  For all other  uses contact the author.
[P.P. Hudec Email].
Last updated: 07/14/07.