Material to seal joints (water from below)

Hello, I have covered slate slabs over the basement door (which is about 1.5m below ground level). The joints are partly somewhat porous and cracked, so water seeps out from the soil when walking over it. Is there a solution to seal these joints waterproof (waterproof joint mortar? Acrylic sealant, etc. There are so many products on the market) or is it generally difficult if water pushes upward from below? Thanks for your assessments. Best regards, Ashley

"Right" would be to remove the slate slabs and properly install a waterproofing layer against pressing water, after that you can lay whatever and however you want. The material could be, for example, Sopro ZR Turbo XXL, a cementitious 2-component waterproofing also against pressing water, on which you can then use tile adhesive. (this would not be the case with bitumen-containing waterproofing)

The "correct" way would be to remove the slate slabs and properly install a waterproofing layer against hydrostatic pressure, then you can install whatever and however you want.
A material would be, for example, Sopro ZR Turbo XXL, a cementitious 2-component waterproofing also against hydrostatic pressure, on which you can then use tile adhesive. (this would not be the case with bitumen-containing waterproofing)

Thanks for the assessment. I will certainly address this in the (near) future. However, the water leakage is not very pronounced at the moment and I thought I could first quickly seal the few spots ("quick-quick") to then later follow your idea of a new waterproofing layer. Is there a product for an initially quick solution?