I need to change the position of the kitchen sink. Therefore, I must cut a square hole large enough to dip the sink bawl on another place of the couner top which is made of 2 inches thick concrete. pl. advise me as to what should be the best method to cut and remove about 24 inch by 18 inch area off the concrete counter top.

HOME IMPROVEMENT : Kitchens : Contemporary (Pt. 4 of 4): Cutting Granite : DIY Network

They missed the type of saw blade. You want a diamond or abrasive blade. e.g. CRL Diamacut Replacement Jig Saw Blade | DB20

Try to cut wet. This will help from clogging the blade and keep the blade cool. You will need a variable speed saw.

You might consider having the cut professionally done or at least practice first.

Remember to support the piece that will fall out.

Professionals will likely slightly route the edge to prevent chipping.

I have had much success using my angle grinder with a diamond masonry blade attatched. It is quite dusty so make a dust room by tacking painter's plastic to the ceiling and let it drape around the workspace. Mark out your cut with china pencil or grease pencil. Support the cut out area and make your cut. You may also want to round over the edges once cut out to prevent hairline cracks from appearing later on. Hope this helps.