Investigation of the effects of different polymer-modified asphalt cements on asphalt mixes at low temperature

2007 ◽  
Vol 34 (5) ◽  
pp. 589-597 ◽  
Author(s):  
K Kandil ◽  
A O Abd El Halim ◽  
Y Hassan ◽  
A Mostafa
Keyword(s):  
Low Temperature ◽  
High Resistance ◽  
Asphalt Concrete ◽  
Elevated Temperatures ◽  
Winter Season ◽  
Experimental Program ◽  
Asphalt Cement ◽  
Modified Asphalt ◽  
Concrete Mixtures ◽  
Polymer Modified Asphalt

The extreme environmental conditions in Canada require the use of asphalt cement that can provide a high resistance to low-temperature cracking during the winter season and a high resistance to rutting due to the elevated temperatures in the summer. Earlier studies showed that such desired improvements in the quality of asphalt cement could be achieved using polymer-modified asphalt (PMA) cement. This paper presents a three-phase experimental program that was carried out to evaluate the expected performance of asphalt concrete mixtures with PMA compared to asphalt concrete mixtures with conventional and air-oxidized asphalt binders. The results of this study show that PMA in asphalt concrete mixes would significantly improve the resistance to cracking (loading and low-temperature). Key words: asphalt mixtures, polymer-modified asphalt, conventional asphalt cement, air-oxidized asphalt, testing.

scholarly journals Evaluation of Mechanical properties for polypropylene Modified Asphalt concrete Mixtures

2017 ◽  
Vol 5 (12) ◽  
pp. 7797-7801 ◽  
Author(s):  
Safaa Moubark ◽  
Farag Khodary ◽  
Ayman Othman
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Asphalt Concrete ◽  
Road Traffic ◽  
Modified Asphalt ◽  
Concrete Mixtures ◽  
Low Temperature Cracking ◽  
Asphalt Modification ◽  
Indirect Tensile ◽  
Polymer Modified Asphalt

It is noticeable that the increase of road traffic during the last two decades in addition to the insufficient degree of maintenance caused an accelerated deterioration of road structure. These roads show early signs of distress such as rutting, cracking, low temperature cracking, ageing and stripping. Heavier loads and higher traffic volume demand higher performance of pavement.  Excellent performance of pavement requires bitumen that is less susceptible to high temperature, rutting or low temperature cracking. Several additives are used to increase the performance of bitumen and the quality of the produced mixtures. Polymers are considered the most widely used additives in asphalt modification that give better performance. The performance of the Polymer-modified asphalt depends on the type and the level of modification the used polymer. The choice of modification level and t modification type depends on the physical properties of the polymer, and its compatibility with bitumen. The polymer can be loosely classified into two categories, Plastomers and Elastomers. The results indicated that, the addition of polypropylene generally improved the mechanical properties of the mixture regardless of the percentage of polymers that added and (PP) content of 5%. it can be noticed that  the performance of PP-modified asphalt mixtures is better  compared with unmodified asphalt concrete mixtures  modifier because it has the highest Marshall Stiffness, indirect tensile strength and unconfined compressive strength

Fracture toughness of polymer-modified asphalt concrete at low temperatures

2003 ◽  
Vol 30 (2) ◽  
pp. 406-413 ◽  
Author(s):  
Kwang W Kim ◽  
Seung Jun Kweon ◽  
Young S Doh ◽  
Tae-Soon Park
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Asphalt Concrete ◽  
Low Temperatures ◽  
Asphalt Binder ◽  
Polymer Modification ◽  
Modified Asphalt ◽  
Temperature Damage ◽  
Polymer Modified Asphalt ◽  
Styrene Butadiene

The fracture toughness of asphalt concrete increases at low temperature and then decreases at temperatures below a certain level. Some polymers are known to have the property of improving the temperature susceptibility of asphalt binder at low temperatures. Therefore, this study evaluated the fracture toughness (KIC) of some polymer-modified asphalt concretes. Low-density polyethylene (LDPE), styrene–butadiene–styrene (SBS), and a mixed polymer of LDPE and SBS were used in this study. The fracture toughness KIC of normal asphalt concrete was compared with that of polymer-modified asphalt (PMA) concrete, and the effectiveness of polymer modification against falling values of KIC was evaluated at low temperatures. The results showed that PMA concretes, in general, showed better KIC than normal asphalt concretes, and the temperature at which the highest KIC was obtained was lower than that in the case of normal asphalt concrete. Therefore, the PMA concretes evaluated in this study had better fracture resistance than normal asphalt at low temperatures.Key words: asphalt concrete, polymer-modified asphalt, PMA, fracture toughness, differential thermal contraction, low-temperature damage.

scholarly journals MAIN PROBLEMS OF MANUFACTURING ASPHALT CONCRETE MIXTURES IN LITHUANIA/ASFALTBETONIO MIŠINIŲ GAMYBOS SVARBIAUSIOS PROBLEMOS LIETUVOJE

2000 ◽  
Vol 6 (1) ◽  
pp. 39-45
Author(s):  
Donatas Čygas
Keyword(s):  
Asphalt Concrete ◽  
High Speed ◽  
Statistical Data ◽  
Concrete Mixture ◽  
Cement Material ◽  
Asphalt Cement ◽  
Concrete Mixtures ◽  
Concrete Quality ◽  
Regressive Analysis ◽  
Speed Gradient

The article describes the main problems of manufacturing asphalt concrete mixtures at the factories under Ministry of Communication in the Republic of Lithuania. The Lithuanian Road Network is up to 21.122 km of state roads. 1.455 km of them are motorways, 3.415 km—national roads and 16.251 km—regional roads. Half of the state roads in Lithuania are paved with asphalt concrete. 98% of the motorways and 36% of the regional roads have asphalt pavement. Asphalt concrete pavement resistance to corrosion can be increased by improving asphalt concrete mixture production technology: ie by updating technological equipment, changing technological conditions and developing new methods of asphalt concrete mixture production. Therefore, the updating of asphalt concrete mixture production technologies is a very important factor for improving road operating properties and ensuring proper duration of asphalt concrete pavements. Here is the essence of the new separate successive technology: crushed stone and sand are mixed with bitumen in the main asphalt concrete mixer, the amount of bitumen being calculated according to the bitumen absorption in the materials. Then the asphalt cement material produced in a separate high-speed mixer is passed, and the whole mixture is remixed in the main mixer and supplied to the customer. Both separate consequent technologies differ from each other in the order of supplying asphalt cement material into the main mixing unit. Separate successive technology was theoretically grounded by the correlation between the technological thickness of bituminous film and the chemical-mineralogical composition and size of constituents, by the correlation between the particle size and their capability to compose aggregates, by the emergence of the oriented binding material coating on the technological bituminous film encoating mineral particles. Special attention is given to the manufacturing of asphalt cement material in a separate high-speed mixer (3 Table). It was theoretically grounded that mineral filler passing through the intensive shift zone between the paddle ends of the high-speed mixer and the walls of mixing chamber disintegrate and new active surfaces become visible. The molecular structure changes and free radicals appear. This intensive mixing guarantees high bitumen adsorption on the surface of mineral filler, which increases asphalt concrete resistance to corrosion and its durability, improves ecological environment in the asphalt concrete plant. In order to confirm the reliability of research results and explain correlative and regressive regularity, statistical data were processed applying statistical data processing programming system “STATGRAPHICS”. The linear regressive analysis for determining close relations of separate asphalt concrete quality indicators with speed gradient of asphalt cement material shift in a high-speed mixer was performed. Therefore, the possibility to change shift speed gradient from 3000 to 5000 1/s is provided in terms of reference for manufacturing asphalt concrete mixing plant. Correlation between separate asphalt concrete quality indicators and asphalt cement material shift speed gradient as well as bitumen amount in the asphalt cement material was determined by multi-dimensional regressive analysis of experimental data. The calculated correlation factor squared (R2) and F criteria indicate the adequacy and reliability of the multidimensional regression model.

Prediction of Low-Temperature Cracking of Asphalt Concrete Mixtures with Thermal Stress Restrained Specimen Test Results

1996 ◽  
Vol 1545 (1) ◽  
pp. 50-58 ◽  
Author(s):  
Hannele K. Zubeck ◽  
Ted S. Vinson
Keyword(s):  
Thermal Stress ◽  
Low Temperature ◽  
Asphalt Concrete ◽  
Probabilistic Model ◽  
Deterministic Model ◽  
Crack Spacing ◽  
Test Results ◽  
Concrete Mixtures ◽  
Specimen Test ◽  
Low Temperature Cracking

A deterministic model and a probabilistic model were developed to predict low-temperature crack spacing as a function of time using thermal stress restrained specimen test results, pavement thickness and bulk density, pavement restraint conditions, and air temperature. The effect of aging on pavement properties was incorporated in the models by predicting the field aging with long-term oven aging treatment in the laboratory. The calculation of the crack spacing is based on the theory that the pavement slab cracks when the pavement temperature reaches the cracking temperature of the mixture and the slab is fully restrained. The deterministic model predicts crack spacing with time, whereas the probabilistic model predicts crack spacing and its variation with time and yields the reliability of the design with regard to a minimum acceptable crack spacing criterion defined by road authorities. The probabilistic model is recommended for use in predicting the low-temperature cracking of asphalt concrete mixtures.

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