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

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

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.

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 .

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 19.0 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 2.525 (gm/cm3) 2.557 (gm./cm3) 1.40 -------

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

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

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 101.1 mm diameter and 203.3mm 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.

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

Methodology Marshall mix design method ASTM- D6927-2010b Indirect Tensile Test (TSR %) ASTM-D D-4867-96) 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

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

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 11.83 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

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.

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 ------ 11.6725 2.5 1.0 rep Dry 12.1285 2 1.5 rep 12.4773 2.0 rep 14.3775 2.1 2.5 rep 13.7755 1.9 3.0 rep 12.0183 1.75 Wet 12 2.25 11.844 12.2234 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

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 .

Mixture Method of adding Dry (2h at 25C0) PSi Wet(24h at 60 C0 + 2h at 25 C0) PSi TSR % Gains % Control -------- 142.5455 113.2727 79.46429 1.0 rep Dry 150.8818 121.8636 80.76761 1.6% 1.5 rep 165.2 135.7364 82.16487 3.3% 2.0 rep 176.2727 157.9455 89.60289 12.8% 2.5 rep 167.6818 149.5455 89.18406 12.2% 3.0 rep 142.4818 122.7545 86.15453 8.4 % Wet 196.1463 162.1727 82.67946 4% 214.76 180.031 83.82891 5.4% 229.1545 205.1237 89.51327 12.6% 2.5 rep 217.9863 204.3637 93.75069 17.9% 185.2263 160.82 86.8235 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 72.5814 1.0 rep Dry 111.85 86.9 77.6933 7% 1.5 rep 132.89 105.5 79.389 9.3% 2.0 rep 130.81 117.6 89.9014 23.8% 2.5 rep 118.6 98.6 83.1366 14.5% 3.0 rep 93.9 69.2 73.6954 1.5% Wet 109.85 90.6 82.4761 8.6% 122.9 105.3 85.6794 10.1% 138.6 120.7 87.0851 19.9% 2.5 rep 133.5 123.6 92.5843 27.5% 124.7 110.9 88.9334 22.5%

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 .

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 201.08 and 461.85 at 40 and 60 respectively, While using wet method mixes replaced with 2 replacement indicated the improvement by

lowering the intercept to 223. 57 and 420 lowering the intercept to 223.57 and 420.92 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.

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 .

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

Mixture Method of adding slope intercept Alpha Mu Control ------- 0.2761 115.72 0.7239 0.286077 1.0 rep Dry 0.2758 110.32 0.7242 0.304215 1.5 rep 0.2682 106.57 0.7318 0.304827 2.0 rep 0.2632 95.071 0.7368 0.292902 2.5 rep 0.2628 83.904 0.7372 0.264558 3.0 rep 0.2619 72.659 0.7381 0.240333 Wet 0.2722 113.72 0.7278 0.345485 0.2681 101.13 0.7319 0.325304 0.267 83.159 0.733 0.284159 0.259 78.063 0.741 0.281254 0.2566 68.633 0.7434 0.222423 Mixture Method of adding slope intercept Alpha Mu Control ------- 0.454 337.71 0.546 0.88017 1.0 rep Dry 0.446 314.5 0.554 0.885757 1.5 rep 0.4435 273.95 0.5565 0.782885 2.0 rep 0.4414 235.65 0.5586 0.729821 2.5 rep 0.4397 201.08 0.5603 0.656849 3.0 rep 0.4519 220.14 0.5481 0.675488 Wet 0.4439 271.98 0.5561 0.831571 257.73 0.791329 0.4405 223.57 0.5595 0.755405 0.4572 256.47 0.5428 0.959383 0.4654 262.93 0.5346 1.032476 Mixture Method of adding slope intercept Alpha Mu Control ------- 0.5438 572.36 0.4562 1.244801 1.0 rep Dry 0.5318 553.47 0.4682 1.197108 1.5 rep 0.5302 477.58 0.4698 1.177549 2.0 rep 0.5235 461.85 0.4765 1.054867 2.5 rep 0.5285 497.34 0.4715 1.096916 3.0 rep 0.5313 513.11 0.4687 1.114436 Wet 0.5381 535.16 0.4619 1.181228 0.5266 488.64 0.4734 1.060027 0.5123 420.92 0.4877 0.928158 0.5244 459.06 0.4756 1.059933 0.547 473.71 0.453 1.195747

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 .

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

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.

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

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