The development and use of flowable mortar for various applications are presented. This research used various methods of backfilling pipe culverts to compare settlement and cost of backfill methods. The research resulted in a method of backfilling culverts with sand backfill to midheight of the culvert and then with a maximum of 5 ft of flowable mortar. The remainder of the backfill is normal embankment or other subgrade treatment. This method was expanded to include installing culverts under bridges and then backfilling under the bridge with sand and flowable mortar in two stages; this method resulted in the bridge check becoming the pavement by removing the bridge curb and handrail. Another use of flowable mortar involves placing a pipe culvert in a deteriorated box culvert and filling the void with flowable mortar. The Iowa Department of Transportation has backfilled an "H" pile and wood plank retaining wall with flowable mortar. The present flowable mortar consists of 2,600 lb of sand, 100 lb of cement, 300 lb of fly ash, and water, which results in a 12-second efflux time for the Corps of Engineers flow cone method CRD-C611-80, approximately 70 gal. The Ames Central Office Materials Laboratory uses submitted sand, fly ash, and cement to develop the desired efflux time. The fly ash content may be increased if the sand is too coarse. Sand gradations are 100% passing 3/4-in. sieve and 0 to 10% passing 200 sieve.
Abstract