Evaluation of Bond Properties of a Fabric-Reinforced Cementitious Matrix for Strengthening of Concrete Structures

In the present study, pull-out and pull-off tests were conducted to examine the bond strength between an inorganic cement adhesive (hereinafter referred to as the “matrix”) and a textile, which composed a fabric-reinforced cementitious matrix (FRCM). The matrix was developed by mixing slag and short fibers in an attempt to improve the alkali resistance and compressive strength. The developed matrix was examined with regard to its alkali resistance, water resistance, and void distribution. Bond tests were conducted in two parts: a pull-out series and pull-off series. The type of textile (carbon or basalt) and the weaving methods were selected as test parameters. These tests were performed in accordance with the methods described in ISO10406-1 (pull-out) and ASTM C1583 (pull-off). The test results showed that the developed matrix was superior to existing mortar methods in terms of alkali resistance, water resistance, and compressive strength. Additionally, the FRCM in which carbon textiles were used exhibited excellent bond performance.

Relation between Asphalt, Asphalt Mortar Properties and HMA Performance

The relationship among asphalt, mortar and mixture performance was analyzed by grey correlation method by means of asphalt rheological test and hot mix freeze-thaw split test in this paper. The results show that the rheological properties of asphalt as well as asphalt mortar are closely related to HMA performance. Rheological index has a good advantage in explaining HMA pavement diseases. Asphalt stiffness, cohesion, yield stress, rutting coefficient, multiple stress creep and recovery have a high correlation with the strength of the mixture; meanwhile, softening point, normal stress, interface bonding ability of asphalt mortar and volume index of mixture have a high correlation with the water stability of the mixture. In the evaluation of asphalt and asphalt mortar, methods such as stress creep recovery, stress scanning (yield stress, normal stress) and interface bond test should be further proposed and popularized.

A Surface-to-Surface Finite Element Algorithm for Large Deformation Frictional Contact in febio

This study formulates a finite element algorithm for frictional contact of solid materials, accommodating finite deformation and sliding. The algorithm uses a penalty method regularized with an augmented Lagrangian scheme to enforce contact constraints in a nonmortar surface-to-surface approach. Use of a novel kinematical approach to contact detection and enforcement of frictional constraints allows solution of complex problems previously requiring mortar methods or contact smoothing algorithms. Patch tests are satisfied to a high degree of accuracy with a single-pass penalty method, ensuring formulation errors do not affect the solution. The accuracy of the implementation is verified with Hertzian contact, and illustrations demonstrating the ability to handle large deformations and sliding are presented and validated against prior literature. A biomechanically relevant example addressing finger friction during grasping demonstrates the utility of the proposed algorithm. The algorithm is implemented in the open source software febio, and the source code is made available to the general public.

Computational Wear and Contact Modeling for Fretting Analysis with Isogeometric Dual Mortar Methods

A finite element framework based on dual mortar methods is presented for simulating fretting wear effects in the finite deformation regime. The mortar finite element discretization is realized with Lagrangean shape functions as well as isogeometric elements based on non-uniform rational B-splines (NURBS) in two and three dimensions. Fretting wear effects are modeled in an incremental scheme with the help of Archard’s law and the worn material is considered as additional contribution to the gap function. Numerical examples demonstrate the robustness and accuracy of the presented algorithm.