Creation of cracks of known sizes in reinforced concrete beams and performance evaluation of silane in concrete bridge decks

Cracks are a major concern for the durability of concrete as they allow the harmful chemicals from outside to penetrate the concrete surface. Investigating the effect of various crack sizes is vital to further evaluate the surface treatments' performance. In this research, a novel technique is developed to create cracks of known size consistently in reinforced concrete beams using a very simple methodology which applies direct tensile load that cracks the beam. A variety of crack sizes is created ranging from very small (<1/100 inch [0.25 mm]) up to ½ inch [12.7 mm] and based on the results, a simple process is outlined which can be used to create predetermined crack sizes consistently. Silane is investigated as a surface treatment material, using Transmission X-ray Microscopy (TXM) and Optical Staining Techniques. The TXM results revealed that samples with silane coatings exhibited eight and half times less penetration of outside chemicals as compared to non-silane samples at a depth of 2 mm. In some samples, defects on the surface of the silane coating such as cracks, caused the coating to lose its efficiency. Quantitative measurements made using optical staining techniques show that silane thickness for all the 14 samples was 2.5 mm. This work shows in field applications that silanes are a useful and practical tool to significantly reduce the permeability of concrete

Performance Evaluation of Silane in Concrete Bridge Decks Using Transmission X-ray Microscopy

The corrosion of steel reinforcement in concrete structures is a most widespread problem. Silane is commonly used as a surface treatment material to reduce the entry of moisture containing harmful chemicals into the concrete matrix, thereby restricting corrosion. There is not a standard test method to evaluate the long-term performance of such sealers when applied on concrete. Moreover, the literature does not have a definitive conclusion on the performance of silanes. In this work, transmission X-ray microscopy (TXM) and optical imaging were used to investigate the mass transport properties and silane thickness of field samples treated with silane to gain insight into the performance of silane coatings. Quantitative measurements using optical staining techniques showed that the average measured silane thickness for all 14 projects was 2.5 mm. The TXM results revealed that, on average, the samples with silane coatings exhibited 8.5 times less penetration of outside chemicals, at a depth of 2 mm, as compared to uncracked samples without silane coatings. This work shows that silanes are a useful and practical tool to significantly reduce the permeability of in-service concrete and resist corrosion

Modelling and Analysis of Surface Evolution on Turning of Hard-to-Cut CLARM 30NiCrMoV14 Steel Alloy

Industrial practitioners are working on predictive solutions for the precise evaluation of input parameters and processed surfaces of engineering materials. To aid the aeronautical industry, this study is an effort to develop the mathematical modelling for comprehensive surface analysis of input parameters and surface finish after dry machining of CLARM HBR, a steel alloy with attractive mechanical properties and wide applications in large caliber gun barrels and high-pressure vessels. Feed rate, rotational speed, and depth of cut were taken as quantitative parameters, whereas machining time was considered as a categorical factor with a classification of three levels. Response surface methodology (RSM) with a central component design has been used for the constitution of the experimental design, mathematical modelling, and analysis of developed models. Eighteen samples were prepared to perform the experimentation for the development of prediction models. The adequacy of the developed models was verified using analysis of variance (ANOVA), and the models were validated using confirmatory trial experiments, which revealed the experimental results agreeing with predictions. The feed rate was the most significant parameter in achieving the desired surface finish. An increase in rotational speed at a low feed rate resulted in very fine surface texture, as though it deteriorated the surface finish at higher feed rates. The superior surface quality obtained was 0.137 μm at parametric settings of 0.19 mm/rev feed, 90 rpm speed, 3 mm depth of cut, and 4 min time. Overall, higher values of surface roughness were frecorded in the third level of process variable time. The developed empirical models are expected to aid manufacturers and machining practitioners in the prediction of the desired surface finish concerning different parameters before the experimentations