Making regular, darker-colored concrete a lighter color.?

Here's what I did: I made a landing out of flat stone for the bottom of my deck stairs. Instead of using mortar (like was used to hold the flat rock of my flower beds together), I used bags of concrete from Lowe's. After the concrete had almost dried, to make the joints nearly flush all around the flat rocks, I sprinkled mortar out of my hand in the joint spaces. Today, the concrete is much darker than the mortar holding flowerbeds together (flower beds' mortar is light gray and the flat rock concrete is dark gray). It doesn't look good. It's not a huge area - maybe 7' long by 6' wide - but I'd like it to match the mortar. Is there anything I can do to lighten the color of the joints between this flat rock that I've already put down? I realize I should have used the same brand of mortar as the guy who installed our flowerbeds but I didn't want to do all the mixing. Would bleach help? An acid-type solution that's used to remove excess mortar from between bricks? Thanks.

Making regular, darker-colored concrete a lighter color.?
Try a 25% mixture of muratic acid and water. Use a stiff brush to apply, and rinse well when done. Careful of the fumes, and use rubber gloves.
Reply:put a yellow bean and flag in water for a dy then run for mayor .let it set for 5.4 miniutes and spit on it.cans are good too.
Reply:i had the same thing happen and this worked got a gallon of

swimming pool shock did a cup at a time in 5 gallons of water and poured on let set 15 min and hosed off took 3 times had a perfecct match and did not hurt the stone

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