While many historical masonry structures stand tall and undamaged, several need varying levels of rehabilitation, strengthening, or even partial or full reconstruction. Masonry is strong in compression, and unless stability is a concern due to slenderness ratios, it rarely fails in situations where it is loaded only in compression. It is weak in tension, however, therefore under excessive eccentric axial loading, or out-of-plane or in-plane lateral loads, tensile stresses may exceed the capacity of the assembly. Common causes of masonry structures’ failure include the deterioration of mortar in the joints and lack of adequate strength due to uneven soil settlement, or unexpected extremities of blast, wind, and seismic loads. In these extreme load scenarios, the weak-links may be low tensile capacity of the assembly (i.e. bond strength), flexural strength of mortar, or in-plane shear strength.

This project aims to propose a method of strengthening masonry systems against these cases, namely durability of mortar, and increasing the flexural and in-plane shear strength of mortar joints. The 4
methodology comprises of using low percentage micro-nano size fibers mixed into mortar binders that are either identical or very similar to the authentic mortar mixture in materials and proportion. The bond-strength of the assembly may or may not increase as a result of the proposed method, but would not be lower than the bond-strength of the original materials.

This project was made possible through Grant MT-2210-08-NC-03 from the National Center for Preservation Technology and Training (NCPTT).

National Center for Preservation Technology and Training
645 University Parkway
Natchitoches, LA 71457

Email: ncptt[at]nps.gov
Phone: (318) 356-7444
Fax: (318) 356-9119