Stochastic simulation of the influence of variation of mineral material grading and dose weight on the homogeneity of hot-mix asphalt

Journal of Civil Engineering and Management

Virbickas³

2013

Self Cite

Bitumen holds the aggregate in hot mix asphalt (HMA). Without asphalt binder, HMA would simply be crushed stone or gravel. A bitumen batching system (BBS) is comprised of bitumen storage, transportation, weighing and discharge equipment in an asphalt mixing plant (AMP). The function of the equipment is to batch the binder heated up to working temperature and to discharge it into a mixer in batches. In the entire system, the binder is exposed to high temperature and oxygen. Bitumen is slowly oxidized when it is in contact with oxygen. The degree of oxidation is highly dependent on temperature, time and thickness of a bitumen film. This article models the key factors influencing on the dynamics of bitumen oxidation in BBS equipment. Stone mastic asphalt (SMA) mixture was produced from the same materials according to the same job-mix formula (JMF) in neighbouring batch type AMP by changing the mixing time of materials from 20 to 60 s. Bitumen binder was separated from the taken SMA samples and its gradation was identified. Thus, Marshall specimens were produced and tested. Penetration Pen 25 of bitumen binder recovered in rotary evaporator, softening point T sp was determined and penetration index I p was calculated. The presented findings of experimental investigation show that the properties of bitumen binder in BBS working at two different technologies changed inconsistently. Due to gravitation, the bitumen intensively flowing into a mixer (BBS1) is impacted by oxidation more than the bitumen batched by a high-pressure pump (BBS2).Keywords: bitumen; hot mix asphalt (HMA); stone mastic asphalt (SMA); bitumen batching system (BBS); job-mix formula (JMF); oxidation, short-term ageing; rheology; penetration; viscosity; asphalt mixing plant (AMP).Reference to this paper should be made as follows: Bražiūnas, J.; Sivilevičius, H.; Virbickas, R. 2013. Dependences of SMA mixture and its bituminous binder properties on bitumen batching system, mixing time and temperature on asphalt mixing plant, Journal of Civil Engineering and Management 19(6): 862-872. http://dx.. Research interests: flexible pavement life-cycle, hot mix asphalt mixture production technology, application of statistical and quality control methods, recycling asphalt pavement technologies and design, decision-making and expert systems theory.Romualdas VIRBICKAS. Quality Control manager of JSC "Fegda", Vilnius. Research interests: research and application of new technologies of roads, urban streets and airport pavements construction, design of roads, urban streets and airport pavements, project and structure inspection, maintenance inspection of roads and urban streets. 872 J. Bražiūnas et al. Dependences of SMA mixture and its bituminous binder properties on bitumen batching system ... Downloaded by [Tufts University] at 12:01 04 November 2014

Section: Introductionmentioning

confidence: 98%

Dependences of Sma Mixture and Its Bituminous Binder Properties on Bitumen Batching System, Mixing Time and Temperature on Asphalt Mixing Plant

Bražiūnas

Journal of Civil Engineering and Management

Virbickas³

2013

Self Cite

“…The values of quantile p z are taken from the table of function ( ) (Sivilevičius and Vislavičius 2008;Sivilevičius et al 2003;Mučinis et al 2009) shows that the number of components in HMA mixture lot is distributed according to the normal Gaussian law. The variation of bitumen content may be determined by standard deviation of its population B σ or variance 2 B σ .…”

Section: A Impact Of the Bitumen Doses Mass On Its Amount In Hma Mixtmentioning

confidence: 99%

“…Scientific experiments conducted in Lithuania (Sivilevičius and Vislavičius 2008) and in other countries (Abdullah et al 1998;Witczak and Fonseca 1996;Hunter 1994;Hurley and Prowell 2005) have shown that reliability and durability of asphalt road pavement depends on the number of HMA components determining the structure and properties of the mixture. Too large or too small amount of free bitumen impairs the structure of HMA mixture, physical and mechanical properties of asphalt pavement layer made of it.…”

Section: Introductionmentioning

confidence: 99%

The Bitumen Batching System's Modernization and Its Effective Analysis at the Asphalt Mixing Plant

Bražiūnas

2010

Transport

Self Cite

Abstract. Some particular aspects such as the improvement methods of technological parameters for hot bitumen storage in a pipeline transport system, transportation and dosed supply to batch asphalt mixing plant (AMP) are evaluated in this paper. Bitumen in asphalt concrete binds together the material of mineral particles into a strong conglomerate of a complicated structure, capable of withstanding the destructive effect of vehicles and the factors on the road pavements. The optimal amount of bitumen determined by calculation and laboratory testing should be maintained in mix batches of hot-mix asphalt (HMA) obtained from AMP mixer. In the periodic type of the asphalt concrete blender mass of the weighted matrix in the all merging batcher's tanks should correspond in percents equally in the HMA to the designed amount of the job-mix formula (JMF). The bitumen batcher does not always weigh bitumen portions precisely. Their mass deviations from the amount determined by JMF and its variation impair HMA composition and performance. In addition, , an additive model for calculating the effect of factors causing the variance of bitumen content in the produced HMA mixture is presented in this current paper as well. The data on statistical evaluation of bitumen batcher's modernization performed at certain Lithuanian Enterprise are discussed. The differences in structures of reconstructed and not reconstructed bitumen batching systems (BBS) are analysed and methods of determining modernization effectiveness are presented. The effectiveness of BBS is analysed too, defining the deviations of bitumen content in subsamples, taken and extracted everyday for two seasons (before and after the batcher's modernization) of HMA mixture production from the value of JMF and comparing them to the values of tolerances. The analysis of column charts and histograms shows that the made modernization helped to increase the precision of supplying the required amount of bitumen to HMA mixture insignificantly. However, the control of BBS has been considerably increased.

“…The analysis of data on rutting indicates that unmodified AC mixtures are rutted significantly more than modified mixtures under similar loading and temperature conditions. The content, structure and characteristics of a HMA mixture used for constructing a pavement layer designed under deterministic or stochastic (Sivilevičius, Vislavičius 2008) methods depend on HMA manufacture in asphalt-mixing plant tolerance (Bražiū nas, Sivilevičius 2010;Sivilevičius 2011b).…”

Section: Introductionmentioning

confidence: 99%

Research and Evaluation of Ruts in the Asphalt Pavement on Lithuanian Highways

Journal of Civil Engineering and Management

Vansauskas

2013

Self Cite

Abstract. When exposed to destructive climate and weather factors and heavy vehicle loads, the pavement wears and deflects. In recent decades, apart from cracks and potholes, the depth of ruts grows and makes an increasing share of the pavement surface. The deeper are the tracks, the poorer are traffic conditions for fast-moving cars: drivers are struggling, speed is decreasing and the number of accidents is increasing. After track depth reaches a critical and permissible limit, the road surface must be repaired or speed limit has to be reduced. The work presents a theoretical analysis of track emergence causes and factors determining their depth. With the help of Mobile Road Research Laboratory RST 28, the track depth of all Lithuanian highways has been measured every 20 metres. The obtained data have been processed using the methods of mathematical statistics. Each road has a sample average of every rut, sample standard deviation and a coefficient of individually measured variation. The paper has drawn histograms, calculated skewness, kurtosis and normal distribution and provided lognormal distribution curves of a probability density function. The visualisation and empirical skewness and kurtosis values have revealed that the depth of the rut distributes according to lognormal rather than normal distribution. The average values of the roads having a dividing strip and standard deviations from the distribution across the road have been received. The given dependence of the rut depth of a standard deviation on the averages of rut depth shows an elastic interface of these parameters (determination coefficient R 2 0 0.741).