I don't have photos , but in our racecar engineering business we use a very powerful cleaner , and I've used it at my house at times too . It soaks in , goes a sort of yellowy colour ( I don't want to be too desciptive , but urine would be a good comparison ) -- it lifts out all the brown and black , ends up with a white foam and quite a strong smell . Waterblast it off , and it looks 10 times better than before .

Inside , we use commerciial grade face masks , outdoors not so critical , but pour it on , broom it , leave maybe 20-30 mins , wash off . I can't recall the branding , but I'm in NZ and its NZ made -- if you are in Aus , Google Workshop Concrete Cleaner and see what comes up .

Our stuff is around $200-220 ( trade price ) for 20 litres but well worth it -- it would do your place at least 5 times at a guess .