I had a similar job. It's much work but it worked for me. The dark brown indoor/outdoor carpet came up easily enough, but I used brake parts cleaner from the dollar store to loosen up the dirty glue lines. Then I scraped up a 200 sq.ft.porch with a scraper till it was as good as sanded. Since it still has discolorations, I put a coat of sandstone colored silicone acrylic concrete sealer down. It looks good now. Hope that helps...wear a back brace too.