A Technique for Evaluating Dental Adhesives
A method is proposed for evaluating the strength of an adhesive joint. It is basically a fracture mechanics approach which recognizes that the strength of a joint depends on adhesive thickness, elastic properties of adhesive and teeth, joint geometry, sizes of flaws, and other factors. The "blister" technique is proposed as a useful means of quantitatively determining the quality of an adhesive joint.
Cohesive-Adhesive Fracture in a Pressurized Double Blister
Abstract If two infinite sheets of different elastic properties are bonded together by an adhesive material of even different elastic properties except for an unbonded strip of width 2a into which pressure is introduced, adhesive fracture can occur by unbonding between the adhesive and either of the two sheets, of cohesive fracture can arise from an unstable flaw within the adhesive. This paper describes an approximate analysis through which the critical applied pressure and preferred locus of fracture initiation can be estimated as a function of the geometrical and mechanical properties of the three layers involved.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.