The Corrosion Characteristics and Tensile Behavior of Reinforcement under Coupled Carbonation and Static Loading
This paper describes the non-uniform corrosion characteristics and mechanical properties of reinforcement under coupled action of carbonation and static loading. The two parameters, namely area-box (AB) value and arithmetical mean deviation (Ra), are adopted to characterize the corrosion morphology and pitting distribution from experimental observations. The results show that the static loading affects the corrosion characteristics of reinforcement. Local stress concentration in corroded reinforcement caused by tensile stress drives the corrosion pit pattern to be more irregular. The orthogonal test results from finite element simulations show that pit shape and pit depth are the two significant factors affecting the tensile behavior of reinforcement. Under the condition of similar corrosion mass loss ratio, the maximum plastic strain of corroded reinforcement increases with the increase of Ra and load time-history significantly.
Mechanical performance of BStIV grade steel bars with regard to the long-term material degradation due to corrosion damage
The mechanical performance of BStIV grade reinforcing steel bars from four different manufacturers was experimentally investigated and evaluated by exploiting the performance indices concept. The experiments included tensile tests, carried out on uncorroded and pre-corroded steel specimens. To corrode the specimens, accelerated laboratory corrosion tests were involved. The later tests were made to assess the expected degradation of the materials mechanical performance with accumulating corrosion damage during the life of a reinforced structure. For the evaluation of the mechanical performance, index QD has been introduced. The index QD considers the combination of tensile strength and tensile ductility in a single quantity by accounting also for scatter in material’s mechanical properties. Index QD can be applied to assess the materials mechanical performance both in the undamaged and in the corroded conditions. In both cases, the materials were ranked based on the outcome of the evaluation of their mechanical performance. Subjective choice is needed in order to consider the effect of corrosion damage on the material’s mechanical performance.
Pyrolysis of soybean oil with H-ZSM5 (Proton-exchange of Zeolite Socony Mobil #5) and MCM41 (Mobil Composition of Matter No. 41) catalysts in a fixed-bed reactor
Soybean oil was pyrolyzed with various catalysts in a fixed-bed reactor under nitrogen flow at 420 and 450°C. The H-ZSM5 catalysts (molar ratio SiO2/Al2O3=28, 40, and 180) and 2wt% (Ga, Al or Cu) impregnated MCM41 catalysts were used in order to investigate the effect of catalysts during the pyrolysis process. The gas products in all experiments were mainly methane, ethane and propylene. The liquid products in the presence of H-ZSM5 catalysts were mainly aromatic components while those with metal/MCM41 catalysts were a mixture of alkanes, alkenes, alkadienes, aromatic and carboxylic acids. The highest coke yield of 4.4wt% was obtained with Ga/MCM41 catalyst at the pyrolysis temperature of 420°C. The effect of catalysts on product yield and composition was systematically investigated.