Wei Ting Lin

Prediction of the Deterioration Depth of Concrete by Accelerating Calcium Leaching Test

The concrete is a solid and porous composite materials, when the concrete exposure to moisture environment for a long-term, the pore water will penetrate into concrete cause hydration products leaching. Leaching of calcium ions increase in porosity and resulting in harmful ions ingress into concrete to reduce strength and durability of concrete. The purpose of this study is to evaluate the effect of water-binder ratio on calcium ion leaching behavior of cement-based material. The ammonium nitrate solution was used to accelerate leaching process. Leaching duration was 56 days, 91 days and 140 days, respectively. The leaching depth and compressive strength were measured. The results showed that leaching resistance increased with a decrease in water/binder ratio. The leaching depth showed that leaching behavior of the specimens without minerals admixtures can be divided into two stages, the first stage was leaching of calcium hydroxide and than the C-S-H gel were leaching.

Properties of Cement-Based Materials Containing Melting Incinerator Bottom Ash

This paper presents an experimental investigation on the effect of incinerator bottom ash (IBA) fineness and the cooled process of molten IBA on fresh mortar properties and compressive strength of hardened mortars. IBA with two finenesses, an original IBA, and a pulverizing incinerator bottom ash (PIBA) powder, with maximum particle size of 4.75 and 0.074 mm respectively were used to partially replace sand and Portland cement at 0%, 10%, 20%, 30%, and 40% by weight. The pozzolanic activity characteristics of powder were obtained from melting the above PIBA in an electric-furnace at 1450 °C for 1 h. and chilled by quenching in water (WIBA) and air (AIBA). Results indicate that incinerator bottom ash caused a reduction in compressive strength, unit weight, and flowability values when used as a replacement for sand and cement. However, IBA can be processed by melting to regain reactive pozzolanic activity, which may be used to partially replace cement.

Seismic Response for a Reinforce Concrete Specimen Considering Corrosive Hazards

This study is aim to evaluate the dynamic response variation of the scale-down reinforced concrete frame specimen under accelerated corrosion conditions. The specimens achieved the accelerated corrosion test by immersing in the accelerated corrosion test. Open circuit potential, corrosion rate, natural frequencies, displacements, accelerations and response spectral curves were tested and discussed. Test results presented that the corroded reinforced concrete specimens presented the changes in the dynamic response especially natural frequencies and response spectrum. This study provided further insight on the variation of seismic response behaviors in the deteriorated reinforced concrete structures and hoped to useful for structural assessments and appraisals applied to full-scale structures.

Variation in Fineness of Cement-Based Composites Containing Sugarcane Bagasse Ashes

This study is aimed to evaluate the effect of sugarcane bagasse ash fineness on the properties of cement-based composites. Three sugarcane bagasse ash contents (10, 20 and 30% by weight of cement) and three particle sizes of bagasse ash (particles less than 45, 75 and 150 μm) were used as a partial replacement for cement in mortar specimens with a constant water/cementitious ratio of 0.55. The pozzolanic strength activity test, compressive strength test and scanning electron microscope observations were conducted and compared. Test results indicated that the compressive strength decreased with the addition of sugarcane bagasse ash content increased. Addition of sugarcane bagasse ash to replace cement in cementitious composites could provide hydration and pozzolanic reaction, but it would still keep more rugged and some larger pores observed from the paste surface and resulted in the weaker microstructures and poorer properties in cementitious composites. In conclusion, the critical usage of sugarcane bagasse ash is 10 % with 45μm particles.

The Component Analysis of Penetration Sealer Materials

Nowadays, its more common of dispensing a topping material like concrete crystalline penetration sealer materials (CSM) onto the surface of a plastic substance such as concrete to extend its service life span by surface protections from outside breakthrough. Its known as the CSM may penetrate into the existing pores or possible cracks in such a way that it may form crystals to block the potential paths which provide breakthrough for any unknown materials. Even though all kinds of test data and researches have been reported to boast of its advantages in both theoretical technologies and application functions, to accept that as an agreed fact, namely the major components and those proportions have not been fully announced in public or research. This study employed various experiments, such as scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), X-ray fluorescence (XRF) and Fourier transform infrared spectroscopy (FT-IR), to identify key components of CSM for developing another type of CSM so that its components could be open for the public. There are two types of commercial CSM adopted for the tests and then thru a series of discusses of test results the most possible components of CSM are proposed as a future reference of CSM related researches.

Effect of Calcination Temperature on Pozzolanic Reaction of Calcined Shale Mortar

This study investigated the influence of calcination temperature on the pozzolanic activity of shale. Calcination temperatures of 500 °C, 600 °C, 700 °C, 800 °C, and 900 °C were used. The calcined shale powder was then passed through a No.200 sieve before being used to replace 20% of the cement in standard mortar samples. X-ray fluorescence spectrometery (XRF) was used to analyze the chemical composition of the calcined shale. In addition, the effects of replacing mortar with calcined shale were also examined with regard to setting time, pozzolanic activity, compressive strength, ultrasonic wave velocity, and the water absorption of the mortar. The test results demonstrate that the chemical composition of SiO2+Al2O3+Fe2O3 exceeded the 70% required by ASTM C618 specifications. The strength activity index (SAI) of calcined shale at 7, 28, 56 days exceeded 75%. At 28 days, the SAI values of samples produced with shale calcined at 700 °C and 800 °C exceeded 99%. After 28 days, the SAI, water absorption, and ultrasonic wave velocity values were nearly identical to those of control samples produced using only cement. Among all shale samples, those calcined at temperatures between 700 and 800 °C demonstrated the highest pozzolanic activity.

Influence of Pro-Coating Coarse Aggregate on Engineering Properties of Recycled Concrete

This study is aimed to investigate the effects of four kinds of pro-coating coarse aggregate included air-dried condition, 50 degrees Celsius curing for 24 hours, saturated lime water curing for 28 days and original recycled aggregate for a comparison group. Performance testing included slump, compressive strength, ultrasonic velocity, absorption and resistivity tests and were evaluated the fresh, mechanical and durability properties. Test results indicated that the specimens containing four kinds of recycled aggregates performed batter workability due to the smooth surface pro-coated with slag. The specimens containing pro-coating aggregate with 50 degrees Celsius curing had lower absorption, higher compressive strength, ultrasound velocity and resistivity than others due to the better denseness and compactness. At the age of 28 days, the recycled aggregates specimens with 50 degrees curing had 22 % higher compressive strength and 40 % lower absorption than the original recycled aggregate specimens. For engineering requirements, pro-coating technology should be applied to improve the engineered properties of concrete and promote the natural resources recycling technology.

Seismic Response for a One-Third Scale-Down Vertical Cylindrical Cask Specimen Using Shaking Table Testing

This study is aimed to investigate the seismic behavior of the freestanding dry storage cask for spent fuel, several shaking table tests were conducted using a scaled cask model for a real assessment of the characteristics of the seismic response of the cask. First, the harmonic excitation test on the pedestal of the cask was performed to estimate the friction coefficient at the interface between the cask and the pad according to the sliding acceleration response of the pedestal. Then, tests for the seismic response of the cask were conducted for two different setups, the vertical cylindrical concrete cask (VCC) and the concrete cask with an add-on shield which has a square pedestal (VCC+AOS), respectively, using the artificial earthquakes compatible to the design spectrum. In order to verify the often-used analysis method for the seismic response of the cask in engineering practice, the explicit finite element software LS-DYNA was adopted to generate the finite element model of the scale cask with the cask/pad interface modeled by Coulomb’s law of friction and to simulate the shaking table tests. Results indicate that the utilized method gave reasonable cask responses if the variation of the friction coefficient at the cask/pad interface was small during the sliding process.

Effect of Fiber Length on Direct Tensile and Impact Strength of Cmentitious Materials Containing Silica Fume

This study is aimed to evaluate the tensile strength and impact resistance of cementitious materials which comprise steel fibers and silica fume in the mixes. Material variables include water-binder ratio, dosage of silica fume, steel fiber length and dosage. A designed tensile strength was used to perform the direct tensile in this study. Test results indicate that the compressive strength, splitting tensile strength and direct tensile strength of specimens for fiber length of 60 mm are higher than that of 35 mm. The inclusion of fibers in specimens containing silica fume has higher compressive and tensile strength; and lower impact resistance than the specimens made with silica fume. Incorporation of steel fiber and silica fume in composites achieves significantly higher increase in compressive strength, splitting tensile strength, and direct tensile strength than only individual use of steel fiber or silica fume and decrease in impact resistance than only individual use of steel fiber. Finally, the proposed direct tensile testing method is suitable for determining the tensile strength of fiber reinforce cementitious materials and generating the tensile stress-strain curves easily.

Engineering Properties of Fiber Cementitious Materials

Fiber cementitious materials are composed of fibers, pozzolan and cementitious. Addition of fibers in cementitious materials may enhance its mechanical properties, particularly tensile strength, and ductility. This project is aimed to evaluate the mechanical properties of fiber cementitious materials which comprise fibers and silica fume in the mixes. Test variables include dosage of silica fume, mix proportions, steel fiber dosage and type. Compressive strength, direct tensile strength and splitting tensile strength of the specimen were obtained through tests. Test results indicate that the splitting tensile strength, direct tensile strength, strain capacity and ability of crack-arresting increase with increasing steel fiber and silica fume dosages. The optimum composite is the mixture with 5 % replacement silica fume and 2 % fiber volume. In addition, the nonlinear regression analysis was used to determine the best-fit relationship between mechanical properties and test parameters.