Ph.D

You have completed post graduation degree in advance construction management so you are eligible for Ph.D course but you must have a valid UGC NET score.
NET stands for National Eligibility Test. The educational qualification required for NET exam is masters degree from a recognized university with above 55% marks. 5% relaxation is given for SC/ST category candidates. Final year student are also eligible for NET exam.
There is no age criteria for NET exam but for JRF posts, your age should be below 28 years.
Some building and construction management courses offer a year out in industry, giving you the chance to develop professional contacts and build on your practical skills. Alternatively, you could apply for a summer placement with relevant building or construction companies.
Make the most of any work placements you do as companies may use them as a way to recruit future employees.

In India, Ph.Ds operate in a three-tiered system, commencing with an undergraduate Bachelor's degree, followed by postgraduate Master's and Ph.D degrees. In some cases, candidates can do Ph.D without doing post graduation too, but they will usually be required to complete a larger coursework component when enrolling for a PhD. So, you can choose what you want to do.
Good news for CSs: There are some universities in India which have recognised the Company Secretaryship qualification as equivalent to postgraduate degree for pursuing Ph.D. Sardar Patel Universit-Gujarat, South Gujarat University-Surat, Maharishi Dayanand University-Haryana, Guru Nanak Dev University-Punjab, Punjab University-Chandigarh, Nagpur University-Maharashtra, etc., are a few names of who have recognized CS course as PG so you can go there to do Ph.D.
If I talk about benefits then you can get yourself an opportunity to go into academics and research part abroad. Even in India, if you get a good opportunity, you can enter into academics as it is also a highly rewarding career. As far as any other job is concerned, the only thing is you get the highest respect of being a Ph.D. As the financial rewards grow only with your experience.
I hope this would suffice.

The Ph.D. or the Doctorate degrees offered for the BBA and MBA students are largely in Management Sciences. Now the universities balance with the fundamental aspect of the knowledge on the subject with adaptability in order to create new knowledge and this is certainly received from the interest of students who wish to go for a doctorate degree. Now there is a difficult task in the course that the students who would undergo Doctorate degree will have to go through thorough academic work and should be able to work individually on any research topic they choose to do and then complete the doctorate degree.
Eligibility criteria are entirely based on the marked obtained by the student in his or her Bachelor degree, be it BBA or Bachelors in general subjects. Candidate with greater scores i.e. above 75% is eligible for post-graduation in any stream be it Management degree or non-management degree.
A student can take up Ph.D. in any disciplinary subjects only if he or she scores 60% marks in Post-graduation from a recognized University in any discipline or 75% marks for migration students i.e. students who are from management related subjects 2 years work experience is required.

You will become eligible to pursue your Ph.D after completing your postgraduate degree and having some relevant experience in the concerned field. There are some good institutes which demand a minimum 3-4 years of work experience to be eligible for Ph.D. They follow the steps like:-
Written exam
Research paper presentation
Interview
Final merit
So, to get into a good college, you have to be more experienced and need to do more research based work.
Yes, you are eligible for Ph.D after completing your PGDM as it is equivalent to MBA from All India University Association. So, if you are having a relevant experience and degree, you can take entrance exams for Ph.D so after those certain steps for enrollment, you will be enrolled in a batch if found eligible.
Hope this information helps.
All the best.