J
J Sid
More than likely John
You can have a look at other threads under the history search section which may give you some answers to other previous issues with this product.
They are usually associated with a lack of product knowledge and as previously stated non sealing.
You will have to pursue contact with your contractor to resolve this product and only if he is reputable will you stand any chance of recourse.
Was the contractor a builder, landscaper, or tiler and who supplied the product?