Fasto Fix Block Fixo mortar used for AAC Blocks, Concrete Block, Siporex Blocks, Fly Ash Bricks. Lion Block Jointer is a pre-mixed cementitious powder adhesive composed of Portland cement, special adhesive and Silica sand. It is formulated as a crack free, superior, flexible, high bonding adhesive for AAC Block, when mixed with water, Fasto Fix Block Fixo Produce a workable mortar. that generates a high adhesive power between block.