Load-bearing capacity of mortar joints between precast elements

摘要

This paper presents an experimental investigation on the load-bearing capacity of mortar joints used in precast concrete structures. The following variables were used in this research: (a) the type of fill-up material: grout, 'dry packed' mortar and without filled-up material; (b) the mortar layer thickness: 15, 22.5 and 30 mm; (c) the ratio of the mortar compressive strength (f_m) to compressive precast concrete strength (f_c): f_m < f_c, f_m = f_c, and f_m > f_c; (d) the concrete compressive strength: normal (35 MPa ) and high (60 MPa); and (e) the employment of additional reinforcement in the connection adjacent area. Some of main conclusions are: (a) the most suitable mortar layer thickness is 22.5 mm, which means about 13% of joint width; (b) using mortar with more compressive strength for filling up the connection f_m > f_c, the mortar joint is not the weak point of the system, but the splitting stress becomes more intense in precast elements; (c) the additional reinforcement at the precast segment end increases the system s ductility as well as restricting the rupture area; however it does not increase the load-bearing capacity of the system.