I recently started work building a brick barbecue. The concrete base turned out perfect, but I didn't get much further than that. I'm having a lot of trouble mixing good, easily workable mortar. The mix I tried is 6:2:1 (sand:lime:cement). Since I'm just getting started in laying bricks, I need to take my time adjusting the bricks into place. This seems impossible with the mortar I made. No matter how much water I put in it, the mortar dries fast and doesn't stick to the bricks (bricks that have been layed 24hrs ago can easily be removed by hand). What am I doing wrong?