basics/.style={minimum width=30mm, minimum height=7.5mm, text centered, draw=black},
  startstop/.style={rectangle, rounded corners, basics, fill=red!30},
  io/.style={trapezium, trapezium left angle=70, trapezium right angle=110, basics, fill=pink!30},
  process/.style={rectangle, basics, fill=blue!30},
  decision/.style={ellipse,basics, fill=yellow!30},
\pgfdeclarelayer{background layer}
\pgfsetlayers{background layer,main}

    \begin{tikzpicture}[node distance = 17mm, auto]
        \node (Sta) [startstop] {Problem Identification};
        \node (Lit) [process, below of=Sta] {Literature Review};
        \draw[arrow] (Sta) -- (Lit);
        \node (Mat) [process, below of=Lit, text width = 5cm] {Materials\\ VG10, VG30, VG40, PMB(P), PMB(E), \& CRMB};
        \node (Agi) [process, below of=Mat, text width = 5cm] {Aging\\ \begin{itemize}
            \item Unaged
            \item Short-term aged
            \item Long-term aged
        \draw[arrow] (Mat) -- (Agi);
        \begin{pgfonlayer}{background layer}
        \node (MatAgi) [draw,fill=green!50,fit= (Mat) (Agi)]{};
        \draw[arrow] (Lit) -- (MatAgi);
        \node (Ana) [io, below of=Agi, text width = 4cm] {Analysis of parameters\\ by linear \& non-\\ linear model };
        \hspace{3cm} \node (Gra) [decision, right of=Ana, text width = 2.5cm] {Binder grading\\ methodology};
        \draw[arrow] (Gra) -- (Ana);
        \node (Con) [startstop,, below of=Gra] {Conclusions};
        \draw[arrow] (Gra) -- (Con);
        \hspace{2cm} \node (Pro) [process, right of=Mat, text width = 4cm] {Basic properties\\ of bitumen};
        \node (Cha) [process, right of=Agi, text width = 4cm] {Characterization at\\ various temperatures\\ (0 to 70 \textsuperscript{o}C)};
        \draw[arrow] (Pro) -- (Cha);
        \begin{pgfonlayer}{background layer}
        \hspace{5cm} \node (ProCha) [draw,fill=green!50,fit= (Pro) (Cha)]{};
        \draw[arrow] (ProCha) -- (MatAgi);
        \draw[arrow] (ProCha) -- (Ana);

New contributor
lohit aditya is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
  • 9
    what is your problem?
    – ljguo
    Sep 21 at 3:46
  • 5
    Please both edit your post to ask a question, and also, please change the title to something less generic, so you might actually attract the attention of those knowledgeable about your issue.
    – frabjous
    Sep 21 at 5:56

1 Answer 1


To long for comment ...

  • Welcome to TeX.SE!
  • Your code is, frankly said, strange. Is this your problem?
  • From your code is not possible to see, how your flowchart should be.
  • Just guessing, that flowchart should be something like this, however, it is not clear, how are nodes connected ...

    node distance = 4mm and 22mm,
      start chain = going below,
      base/.style = {draw, 
                     text width=32mm, align=center},
        io/.style = {base, 
                     trapezium, trapezium stretches body,
                     trapezium left angle=70, trapezium right angle=110,
  decision/.style = {diamond, aspect=2, 
                     draw, fill=green!30, 
                     align=center, inner xsep=0pt},
%                 = {ellipse,basics, fill=yellow!30}, ?
       FIT/.style = {draw, fill=green!50, fit=#1},
   process/.style = {base, fill=blue!30},                 % <---
 startstop/.style = {base, rounded corners, fill=red!30},   % <---
       arr/.style = {thick,-Stealth},


    \begin{scope}[nodes={on chain, join=by arr}]
\node (Sta) [startstop] {Problem Identification};
\node (Lit) [process]   {Literature Review};
\node (Mat) [process]   {Materials\\ VG10, VG30, VG40, PMB(P), PMB(E), \& CRMB};
\node (Agi) [process]   {Aging\\ 
                            \item Unaged
                            \item Short-term aged
                            \item Long-term aged
%            \draw[arr] (Lit) -- (MatAgi);
\node (Ana) [io]        {Analysis of parameters by linear \& non-linear model};
\node (Gra) [decision]  {Binder grading\\ methodology};
\node (Con) [startstop] {Conclusions};

\node (Pro) [process, right=of Mat] {Basic properties\\ of bitumen};
\node (Cha) [process, right=of Agi] {Characterization at various temperatures 
    \draw[arr] (Pro) -- (Cha);
\scoped[on background layer]
\node (MatAgi) [FIT=(Mat) (Agi)]    {};
\node (ProCha) [FIT=(Pro) (Cha)]    {};


enter image description here

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