Introduction. The composition of the grading of the mineral part of the asphalt mixture significantly affects the properties of road asphalt, namely its strength, roughness, durability, stability, reliability, quality, etc., especially when using secondary industrial waste. The designing of asphalt mixture grading (hereinafter referred to as AM) involves the calculation of its parameters that, among other things, meet the requirements of Tables 6 and 7 of DSTU B V.2.7-119:2011 [1].
Designing the aggregate composition and binder content of an AM that meets the specification requirements is a lengthy trial-and-error procedure, and success in designing an AM largely depends on the designer’s experience. This difficulty can be overcome by the development and implementation of computer software for designing the optimal AM parameters to obtain the desired properties and control them.
In general, three main approaches have been proposed to computerize the computations for processing laboratory test results and optimizing the parameters of the AM:
1) Excel spreadsheets for performing a volumetric analysis of AM (Asphalt Mix Design Tools), for example, according to the methodology of Part 5 of the manual [3];
2) optimization of the process of designing the optimal AM using artificial neural networks (hereinafter referred to as ANN) and genetic algorithm (hereinafter referred to as GA), for example, [4];
3) improving the design and management of AM production by means of computer simulation modeling and optimization of AM parameters in real-time [5].
Excel spreadsheets are the most common in the construction industry worldwide. They are offered on the software market or developed on their own by individual specialists who are familiar with Excel. Microsoft Excel includes a so-called Solver, which uses a GA to find the optimal number of components of the mineral part of the AM. In addition, the Visual Basic for Application (VBA) programming language available in Excel makes it possible to create programs that correspond to the complexity of the problem of optimizing the parameters of the AM and have a convenient user interface.
A modern approach to optimizing the process of AM designing based on ANN models of various types, for example, is proposed in [4]. Artificial intelligence tools have gained popularity in recent years.
In pavement design engineering, ANN can be used to interpret complex data obtained from field and laboratory tests or even computer simulation modeling. ANN is mainly used in three main areas of pavement construction and repair, namely, in assessing the structural condition of the pavement, predicting the emergency condition of the pavement, and evaluating the properties of asphalt concrete.
In our opinion, we can conclude that it is expedient to solve the problem of finding the optimal composition of grading of the mineral part of the asphalt mixture in the Microsoft Excel spreadsheet processor, as it is the most common in the construction industry and accessible to most users.
Problem Statement. The composition of grading of the mineral part of the asphalt mixture significantly affects the properties of road asphalt concrete, namely its strength, roughness, durability, stability, reliability, quality, etc., especially when using secondary industrial waste. The designing of asphalt mixture grading (hereinafter referred to as AM) involves the calculation of its parameters that, among other things, meet the requirements of Tables 6 and 7 of DSTU B V.2.7-119:2011 [1]. Taking into account the considerable labor intensity of optimizing the grading of AM, it is advisable to carry it out using computer software, relying on the most common and well-known software tools, namely the Microsoft Excel spreadsheet processor. The development and implementation of such software will contribute to the development of the theory of designing the grading of AM and facilitate its practical application.
Purpose. The objective of the article is to solve the problem of finding the optimal composition of grading of the mineral part of the asphalt mixture that meets the requirements of state standards [1, 7, 8, 9] using the Microsoft Excel spreadsheet processor without the use of macros and VBA.
Materials and methods. The Microsoft Excel spreadsheet processor was used to optimize the designing of grading of the AM.
Results. A nonlinear mathematical model of the problem of optimizing the grading of the mineral part of the AM with integer variables and constraints has been developed, which should be solved by the developed method. However, if we look for an approximation to the curve with the maximum density gradation, then it becomes possible to use the method of the reduced gradient.
Conclusions. The analysis of available sources of information has shown that solving the problem of designing the optimal grading of the mineral part of AM requires the use of modern computer software packages to reduce the time spent on processing and analyzing the results of laboratory tests.
The most common software in the construction industry, in particular in the laboratory support for the production of asphalt mixtures, is the Microsoft Excel spreadsheet processor. The article demonstrates a methodology for solving the problem of optimizing the grading of the mineral part of the AM in Microsoft Excel without the use of VBA macros, which allows processing and analyzing the results of laboratory studies by specialists who are not familiar with programming.
