here's the procedure I use to fix my sidewalk and create a simple concrete ramp I did this over the span of three days first I removed the old broken concrete and discarded it next they use my grinder to make a ledge on the higher slab be careful and wear masks there is lots of dust after I use some paper clean degreaser to clean off the surface and let it dry the next day I poured some planter top X concrete this stuff sets very fast you have about five minutes to work with it remember do not over mix you don't want it to be soupy slowly trowel your concrete on the sidewalk use a paintbrush with water to flatten the trowel lines now let it sit and wait a bit don't walk on it for at least a day there are a few different ways to fix a sidewalk but I found this work best for me feel free to contact me with any questions