WEED CONTROL IN JOINTS OF CONCRETE BLOCKS AND OTHER PAVING STONE

摘要

Joint filing sands for concrete and other paving stone arc known to act as substrate for weed growth. The present invention drastically reduces the necessary weed control work by making the joint filling sand a hostile substrate for plant and fungus growth by the use of environmentally acceptable slow release mineral additive. The additive having similar grain size distribution and with similar mechanical and rheological properties forms an integral part of the joint filling sand. The specific gravity of the additive is lower than quartz sand imparting a tendency for the additive to migrate towards the top part of the joint. The additive leads to pore waters being rich in sodium and at high pH, both qualities being maintained over long periods of time. The mixture of additive and sand can be handled and applied using conventional laying techniques and equipment, observing usual precautions as used for mortar or cement mixes with sand. In the environment, reaction with COin the air or in the soil porosity will inactivate the causticity, yielding harmless carbonate salts.