BEDDING MORTAR

Bedding mortar is a high slump, high cement containing material that if placed properly in an approximate one-inch thickness, can effectively double the tensile and shear strength of the joints, and significantly reduce the amount of seepage through lift joints. However, the use of bedding mortar does create complications in construction schedules. The mortar fills in the voids between lifts, and acts as an adhesive between layers of concrete, however the joints must be kept moist and clean between construction of lifts. This can consume a lot of time and effort in the construction practice, and is thus of major concern to the contractors. An integrated transition between lift joints can also be accomplished with the use of bedding mortar because the mortar accepts aggregate into its matrix that is being segregated. This increased uniformity greatly aids in preventing seepage problems. Mortar elastic strips impregnated with chemical grout which expand when in contact with water can be used in conjunction with bedding mortar. This expansion also serves to fill the voids, and reduce permeability. The upstream face of the RCC dam almost always requires bedding mortar because of its direct contact with water. Using bedding mortar on the upstream face decreases the damís overall permeability. The placement of the bedding mortar can prove to be a very complicated task because the mortar placement is usually combined with the placement of RCC, and facing concrete. These processes occur at the same time and in the same small area. The placement requires a very detailed planning and scheduling scheme in order to keep the project on the correct time frame.