Distribution of Lithium Nitrite Injected into Concrete and Its ASR Suppression Effect

In this research, lithium nitrite was injected into ASR-deteriorated concrete specimens made with reactive aggregates in order to suppress further deterioration. The amount of injected lithium nitrite was set to three different levels, and the subsequent expansion behavior and area of lithium permeation were investigated. The area of permeation was checked using the coloring reagent TDI. It was found that the prescribed amount of lithium cannot be injected fully into the non-deteriorated specimens. When the lithium was injected at an early stage of deterioration, the area of permeation was small and the ASR suppression effect was small regardless of the injection amount. Also, the expansion reduction effect was evident when the lithium was injected into the considerably cracked concrete

New Development of the J -Based Fracture Testing Technique for Ceramic-Matrix Composites

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65733/1/j.1151-2916.1994.tb09756.x.pd

Experimental determination of the stress-crack opening relation in fibre cementitious composites with a crack-tip singularity

A J -based-fracture-testing method is presented for determining the bridging-stress-crackopening-displacement (σ-δ) relationship in fibre-reinforced composites where the crack-tip toughness is not negligible. The J -based technique originally proposed for concrete has been well-established for cementitious composites where the fracture process is primarily dominated by the formation of a fracture-process zone and the contribution of the crack-tip toughness is negligibly small. In this study, the J -based technique is further extended to cover materials for which the crack-tip stress singularity coexists with the fracture-process zone. This extended version of the J -based technique explicitly accounts for the crack-tip singularity while considering the fracture-process zone. This newly derived testing technique has been applied to a high-strength-mortar (HSM) reinforced with carbon and steel fibres where the fibrebridging toughness can be of the same order of magnitude as the crack-tip toughness. The validity of the σ-δ relationships deduced has been examined by comparing with results obtained from direct uniaxial tension tests. It is suggested that the J -based-fracture-testing technique can provide reasonable σ-δ relationships and fracture parameters in a fibrereinforced HSM.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44728/1/10853_2004_Article_BF00356823.pd

Task Group D - HPFRCC Design Assumptions - Conclusions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84786/1/HPFRCCDesignAssump_LiAndRokugo2005.pd

Thermal stress estimation in relation to spalling of HSC restrained with steel rings at high temperatures

This paper reports on an experimental study regarding the behavior of steel ring-restrained concrete in response to fire exposure. The study was conducted to enable estimation of thermal stress based on steel ring strain in such concrete under the conditions of a RABT 30 heating curve. The specimens used were made from high-strength concrete (Fc: 80 MPa) restrained using steel rings with thicknesses of 0.5, 8 and 18 mm