Project Details

Establishing vegetation at the end of construction projects is required on areas where soil is exposed.  Grass is commonly the preferred vegetation, and when grown from seed, mulch is needed to protect the seeds and prevent erosion.  Straw is the most widely used mulch as it is relatively inexpensive and effective for establishing grass.  In order to prevent the straw from blowing away, binding agents, commonly known as tackifiers, are applied to hold straw together like a blanket until the grass is established. Emulsified asphalt has been widely used as a straw tackifier and this research was focused on testing the effectiveness of a variety of potential alternatives for preventing straw from blowing away. The primary objectives of the project were to determine the effectiveness of each potential tackifier to withstand wind and rain events, and to determine if they had any effects on grass growth. A significant portion of testing was completed using a wind tunnel to compare failure wind speeds of these products at different application rates and under a range of conditions. In general, wet straw was resistant to failure up to the maximum wind speed of 72-80 km h-1 (45-50 mi h-1) even without tackifier. Products tested under gusty wind conditions failed at lower wind speeds than under steady conditions. Tackifier application rates below those recommended by the manufacturer were significantly less effective at withstanding wind, while applications beyond recommended did not always significantly improve stability for most products. Hydromulch products, made of paper and/or wood fiber, were as effective as asphalt in resisting failure, and some have a much lower material cost. There were few negative impacts on grass growth when these products were applied to straw. Overall, the lower cost hydromulches at 1120 kg ha-1 (1,000 lb ac-1) and plantago at 224 kg ha-1 (200 lbs ac-1) would be well suited for replacing emulsified asphalt on construction sites.