1. Amjad Hamd Khalil Albayati Assist Professor. Civil Engineering.
Laboratory Investigation in the Hydrated Lime Effect on Asphalt Concrete Mixture
Amjad Hamd Khalil Albayati
Assist Professor. Civil Engineering.
University of Baghdad
Ahmad Mahir Mohammed Alani
M.Sc. Student. Transportation Engineering
The First National Conference for Engineering Sciences
FNCES '12
Alnahrain University
Baghdad, Iraq
7-8 November, 2012

2. Outline Definition Objectives Materials Characterization
Application of Introducing Hydrated lime Into Mixture
Specimen Preparation
Methodology
Results
Conclusions

3. Definition
Hydrated lime : Ca (OH)2 is a Dry Powder mainly Composed of Calcium Hydroxide Ca(OH)2. It is obtained by Hydrating Quicklime using Specific Equipment Called Hydrators Quicklime is manufactured by Burning Limestone of Very High Purity at temperatures around 900°C in Dedicated Kilns
According to National Lime Association Hydrated lime rate multiple benefits for pavements:
Hydrated lime reduces stripping.
It acts as a mineral filler, stiffening the asphalt binder and HMA.
It improves resistance to fracture growth (i.e., it improves fracture toughness) at low temperatures.
It favorably alters oxidation kinetics and interacts with products of oxidation to reduce their deleterious effects.
It alters the plastic properties of clay fines to improve moisture stability and durability
These improvement has led to increase in life and decrease in life cycle cost.

4. OBJECTIVE
Evaluate the effectiveness of using Hydrated lime as a (partial substitute ) by weight of filler (lime stone powder) with five consecutive percentage namely (1.0 , 1.5 , 2.0 , 2.5 , 3.0) % by weight of aggregate using aggregate treatment methods .
Evaluate the influence of the method of addition of hydrated lime on the mechanical properties of the resulting HMA mixtures. By comparing the wet and dry methods of lime application methods .

5. Materials Characterization
Asphalt
The asphalt in this study is produced in Dura refinery was 40/50 its widely used and acceptable in Iraq.
Aggregates
Nibi crushed aggregate was used it tends with maximum size up to mm and 25.0mm respectively for each layer (Wearing and Binder)
Penetration
(ASTM-D5)
Softening point
(ASTM-D36)
Specific gravity
(ASTM-D70)
Flash point
(ASTM-D92)
Ductility
(ASTM-D113)
45mm
49 C0
1.04
290 C0
150cm
Bulk Specific gravity
(ASTMC127 and C128)
Apparent Specific gravity
Percent water absorption
%wear
(Los Angles Abrasion)
(ASTM-C131)
Coarse aggregate
2.607 (gm./cm3)
2.637 (gm/cm3)
0.435
10.89
Fine aggregate
(gm/cm3)
(gm./cm3)
1.40

6. Specific gravity (gm./cm3) Specific surface (m2/Kg)
Mineral Filler
Calcium carbonate CaCo3 and hydrated lime (calcium hydroxide ), were used and collected from local Vendor , hydrated lime were used a partial substitute of filler with five percentage by weight of aggregate (1 , 1.5, 2 , 2.5 , 3) %.
Material property
Hydrated lime
Limestone
Specific gravity (gm./cm3)
2.33
2.71
Specific surface (m2/Kg)
195 80
-100 Mesh (150 μm)
-200 Mesh (75 μm)
%100
%95
%75
Chemical composition
Hydrated lime
limestone
% Ca(OH)2 92
% CaO
56.1
% Mgo
0.3
% SiO2
01.38
% R2O3
0.6
% Al2O3
0.72
% CaCo3
2.3
% Fe2O3
0.12
% Al2O3+ % Fe2O3
0.5
% MgO
0.13
0.9
% SO3
0.21
%Insoluble in acid
1.0
% L. O. I.
40.65
% loss of ignition
24.2 PH
12.2

7. Application of Introducing Hydrated lime Into Mixture
Two method were used : Dry method follow the normal procedure for preparing the general mix with while for wet method it involves spreading lime powder onto the aggregate that has been wet by water to approximately 2 to 3% over its saturated surface dry (SSD)
The process were not “marinating” This is based on conclusions by(McCann and Sebaaly 2003). In fact, A 48 hour marination time was used to allow for any pozzolanic reaction that might occur between the aggregates and lime
that part of hydrated lime which is not adhered to aggregate will remain through the mixture and will improve the whole mixture and asphalt properties

9. Specimen Preparation
Specimen prepared for this study , have the diameter of 100mm and height of 63 mm for Marshal and Indirect Tensile test were compacted with 75 blows per each face , while for Indirect Tensile test the blows will less in order to produce HMA with targeted Air voids between 6-8% to accelerate the potential damage of moisture in specimen.
Superpave Gyratory Compactor were used to fabricate HMA specimens with 50 gyration of sample mm diameter and mm height to quantify the effect of hydrated lime on rutting potential under the repeated load .
Marshall test device used to evaluate the stability and flow properties if asphalt concrete and indirect tensile test with loading strips. The Pneumatic Repeated Load System(PRLS) Was manufactured under the auspices of the Civil Engineering Department of University of Baghdad by (Albayati 2006). Used haversine repeated loading to achieve the rutting behavior of cylindrical specimens.

10. 22 HMA Mixture Wearing Binder Control
(1.0 ,1.5 ,2.0 , 2.5 ,3.0) Dry lime replacement
(1.0 ,1.5 ,2.0 , 2.5 ,3.0) Wet lime replacement
Binder
Control
(1.0 ,1.5 ,2.0 , 2.5 ,3.0) Dry lime replacement
(1.0 ,1.5 ,2.0 , 2.5 ,3.0) Wet lime replacement

11. Methodology Marshall mix design method ASTM- D6927-2010b
Indirect Tensile Test (TSR %) ASTM-D D )
Permanent Deformation : in PRLS, Controlled stress test applied to 10,000 (rectangular haversine wave ) repeated load pulses, with a load period of 0.1 second and 0.9 second respectively, to the specimens to make maximum damage to the specimens. With the stress levels of 20 psi at temperatures 20C,40 and 60C

15. Result – Marshall Mix Design
Marshal properties will improved using hydrated lime the improvement were significant using dry method and less effect from wet method.
optimum asphalt content were increase due to the increase in hydrated lime percentage attributed to the higher specific area of 190 m2/Kg of hydrated lime as
Mixes made with hydrated lime showed a trend of decrease in unit weight as filler content decrease for both dry and wet especially in wet method. This may be explained by the fact that the specific gravity for HL 2.331gm/cm3 is less than for filler (limestone ) 2.71 gm./cm3 and swelling for hydrated lime up by the effect of mixing heating

16. Mixes with 2%, 2.5% , 3% possess higher increase in air voids the increment where very significant in wet method for binder coarse and this is probably due to the fact that hydrated lime had better coverage on aggregate particles and this gave higher absorption.
Using dry method HL replacement of 2 % possess higher stability of 14.47KN for wearing and 2.5 % exhibits KN for binder coarse show a Gains in stability by18.2% and 10.6% respectively
while for the wet method the effect were insignificant in spite of increasing the stability for both layer form table mixture with 2 % for wearing and binder respectively were show gains by 4.5% and 14.8% respectively

17. Hydrated lime mixes for marshal stability show a trend of proportionate of increase up to maximum value and then started to decrease as the % of HL increase .
after a certain level of replacement ,mixes become stiffer and require a greater compaction effort
marshal design method mixes with 2% replacement show better results by giving high stability and minimum flow and air voids for both dry and wet.

19. Marshal stability (KN) at 60C0 for 24 h Min. Flow (mm)
Wearing
Type of adding
Marshal stability (KN) at 60C0 for 24 h
Min. Flow (mm)
Control
------
2.5
1.0 rep
Dry 2
1.5 rep
2.0 rep
2.1
2.5 rep
1.9
3.0 rep
1.75
Wet 12
2.25
11.844
2.75
11.51
10.224
Binder
Type of adding
Marshal stability (KN) at 60C0 for 24 h
Min Flow (mm).
Control
------
10.57
2.25
1.0 rep
Dry
10.32
2.75
1.5 rep
10.79
2.5
2.0 rep
11.5
2.5 rep
11.83
3.0 rep
11.06
1.75
Wet
11.26 3
11.21
12.42
11.4
10.63

20. Indirect Tensile Strength
hydrated lime increase the indirect tensile strength of conditioned specimens of lime treated mixes.
for wearing , using dry hydrated lime method there is an increase in TSR of lime treated mixture by 1.6%, 3.3%, 12.8%, 12.2%, 8.4%, when 1%, 1.5%, 2%, 2.5% and 3%, hydrated lime is added to replace the lime stone dust ,
while the gains in TSR using the wet method for adding hydrated lime seems to be very effective and significant in improving the bonding between aggregate and film thickness , it can be see that the TSR increase by 4%, 5.4%, 12.6%, 17.9%, 9.2% respectively from 1 to 3% replacement.
similar the same behavior are presented in binder coarse , were mixes exhibit higher TSR for both treatment dry and wet .

21. Mixture
Method of adding
Dry (2h at 25C0)
PSi
Wet(24h at 60 C0 + 2h at 25 C0) PSi
TSR %
Gains %
Control
1.0 rep
Dry
1.6%
1.5 rep
165.2
3.3%
2.0 rep
12.8%
2.5 rep
12.2%
3.0 rep
8.4 %
Wet 4%
214.76
5.4%
12.6%
2.5 rep
17.9%
160.82
9.2%
Mixture
Method of adding
Dry (2h at 25C0)
PSi
Wet(24h at 60 C0 + 2h at 25 C0) PSi
TSR %
Gains %
Control
100.1
72.654
1.0 rep
Dry
111.85
86.9 7%
1.5 rep
132.89
105.5
79.389
9.3%
2.0 rep
130.81
117.6
23.8%
2.5 rep
118.6
98.6
14.5%
3.0 rep
93.9
69.2
1.5%
Wet
109.85
90.6
8.6%
122.9
105.3
10.1%
138.6
120.7
19.9%
2.5 rep
133.5
123.6
27.5%
124.7
110.9
22.5%

22. Low levels of hydrated lime reduced the stripping rating drastically
Low levels of hydrated lime reduced the stripping rating drastically. Increasing the hydrated lime content beyond a threshold value and did not seem to reduce the stripping resistance any further.
comparison between dry and wet method effect on both (wearing and binder). show that Wet method seems to be more effective and gave higher TSR than dry method .

23. Permanent Deformation
hydrated lime improve the permanent deformation parameter . at lower temperature HL did not extend a significant effect on treated mixture ,this due to that fact that hydrated lime behave as “inert filler” and less active chemically. And the effects of HL are diminished .
At moderate and higher temperatures hydrated lime show better performance , mixture that exhibit lower intercept value with flatter slope trend represent a higher rutting resistance at all .
as well as for wearing mixture replaced with 2.5% and 2% show the lower intercept value with and at 40 and 60 respectively,
While using wet method mixes replaced with 2 replacement indicated the improvement by

24. lowering the intercept to 223. 57 and 420
lowering the intercept to and with respect to 40 and 60 C
it also appears that the addition of more than 2.0% of hydrated lime especially using wet method did not improve the resistance of the mixtures to permanent deformations (can easy explained by increasing in plastic deformation properties of the mixture and excessive air voids including) , as the time to failure for the 3.0% case was not different from the time to failure of the 2.0% case.

25. over all evaluation can led to observe that dry method could exhibits lower intercept value than wet method but wet method extend lower rate of decreasing in (a) vale.
thus for both method a significant increasing to the desired stiffness to withstand the loads and the desired elasticity to accumulate only minimal permanent deformation
Synergistic trends was found when replacing hydrated lime by both methods on Binder coarse, (a) value increased with increase irrespective of aggregate .

26. Effect on rutting behavior of asphalt mix
Parameter
Definition
Effect on rutting behavior of asphalt mix
High value
Low Value
Slope (a)
The rate of change in the permanent strain
as a function of the change in loading cycles
High rutting
Low rutting
Intercept (b)
The permanent strain at number of cycles
(N) equal to 1
Alpha ( α)
rate of decrease in permanent deformation as the number of load applications increases
Mu( μ)
represent the constant of proportionality between permanent and elastic strains

27. Mixture
Method of adding
slope
intercept
Alpha Mu
Control
0.2761
115.72
0.7239
1.0 rep
Dry
0.2758
110.32
0.7242
1.5 rep
0.2682
106.57
0.7318
2.0 rep
0.2632
95.071
0.7368
2.5 rep
0.2628
83.904
0.7372
3.0 rep
0.2619
72.659
0.7381
Wet
0.2722
113.72
0.7278
0.2681
101.13
0.7319
0.267
83.159
0.733
0.259
78.063
0.741
0.2566
68.633
0.7434
Mixture
Method of adding
slope
intercept
Alpha Mu
Control
0.454
337.71
0.546
1.0 rep
Dry
0.446
314.5
0.554
1.5 rep
0.4435
273.95
0.5565
2.0 rep
0.4414
235.65
0.5586
2.5 rep
0.4397
201.08
0.5603
3.0 rep
0.4519
220.14
0.5481
Wet
0.4439
271.98
0.5561
257.73
0.4405
223.57
0.5595
0.4572
256.47
0.5428
0.4654
262.93
0.5346
Mixture
Method of adding
slope
intercept
Alpha Mu
Control
0.5438
572.36
0.4562
1.0 rep
Dry
0.5318
553.47
0.4682
1.5 rep
0.5302
477.58
0.4698
2.0 rep
0.5235
461.85
0.4765
2.5 rep
0.5285
497.34
0.4715
3.0 rep
0.5313
513.11
0.4687
Wet
0.5381
535.16
0.4619
0.5266
488.64
0.4734
0.5123
420.92
0.4877
0.5244
459.06
0.4756
0.547
473.71
0.453

28. Resilient Modulus
mixtures treated with hydrated lime performed significantly better than the control.
contribution of hydrated lime show gains in Mr property neglecting the effect at 20C.
increase the Mr with increasing hydrated lime content for dry and wet replacement at higher temperature , hydrated lime behave as active filler and reduced the tensile strains within the pavement help to reduce the damage effect induced form heavy vehicles traffic .

30. conclusion
Based on this study, the following conclusions can be drawn:
1. mixes replaced with dry and wet hydrated lime replacement show better performance than control mixes.
2. Using 2.0% for dry method and 1.5% seems to be the best Hydrated lime replacement percentage for both dry and wet replacement .
3. Replacing 2.0% hydrated lime by dry method increasing the stability of control mixture by 18.2% and 10.6% for wearing and binder respectively with notice that the increase beyond thresholds of this percentage may degrade marshal properties as well as reduce the stability and increasing air voids ,
while this effect could be less effect when implementing the wet replacement using the same percentage showing increase stability by 4.5% and 14.8% for wearing and binders coarse respectively

31. 4. With increasing of lime replacement percentage TSR% will increase due to the effect of hydrated lime as anti- stripping agent , using the two method on both layers TSR% show a gains by at 2.0% replacement by 12.8 % and 23.8% for dry replacement wearing and binder and 12.6% and 19.9% for dry method with respect to these layers .
the result indicated that Hydrated lime acts as anti- stripping agent by enhance asphalt-aggregate interfacial bonding that produces better resistance to stripping.

32. 5. Hydrated lime improve the rutting resistance of HMA mixtures by increasing the stiffness , exhibiting mixes with lower slope value and flatter intercept . reaching its optimum value then started to increase due to the variation in volumetric properties .
6. Resilient modules will improve adding hydrated lime at three temperatures specifically when using wet method at higher temperature ,this will help by decreasing the value of permanent strains and gave higher resilient modules at higher temperature .
7. Overall description aids that the wet method is better than dry method despite the little effect on Marshall properties when comparing all the test result and seems to provide l better performance for pavement

33. Thank You For Your Listening