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Wrinkling is one of the most common flaws of woven fabrics in domestic use and industrial applications. It is necessary to develop an objective evaluation method to quantify the smoothness appearance of fabrics effectively. Herein, a fabric multi-deformation tester (FMDT) was designed to evaluate the smoothness appearance of garment fabrics by one sequential mechanical test, overcoming the main difficulties of the existing visual measurement methods for wrinkling evaluation of fabrics with complex colors and patterns. The k-means clustering algorithm was used to objectively cluster the fabric samples based on the characteristic parameters, including the wrinkle-induced residual force ( F wr), hysteresis distance ( H fr), position deflection ( D fr) and stretching recovery slope ( S tr), from the testing curve and the thickness and weight of fabrics, and comparisons with subjective evaluation were also conducted. The results reveal that the k-means clustering is able to classify the smoothness appearance of fabrics using the selected characteristic parameters, showing a good consistency with the subjective clustering results. The feasibility of using the mechanical and deformation properties of textiles to characterize fabric smoothness appearance is proved, and the FMDT provides a potential method to analyze the wrinkling of fibrous materials in a convenient way.

Bottle-recycled polyethylene terephthalate (R-PET) fibers were fabricated by the melt spinning method. Based on characteristics of R-PET chips, this study involved a primary exploration of the spinning parameters, including spinning temperature, spinning speed and spinneret plate. The properties of R-PET and original PET (O-PET) fibers were compared using scanning electron microscopy (SEM), tensile testing, sonic orientation, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Apparent morphological observation displays an irregular cross-sectional shape and a scattered diameter distribution for R-PET fibers. Compared with O-PET fibers, R-PET fibers demonstrate a greater breaking strength and smaller elongation at break, resulting from the lower crystallinity and higher degree of orientation. Furthermore, the R-PET fibers have the same chemical structure as that of O-PET fibers demonstrated by FTIR spectroscopy, but TGA results show that thermal stability of R-PET fibers is significantly inferior to that of O-PET fibers, as a result of too many impurities and oligomers during the recycling process.

The pore structure parameter of cement mortar with different air contents was tested through Automatic Mercury Porosimeter and Air Void Analysis of Hardened Concrete. A fractal model based ...

This study investigated the effects of the water-cement ratio and low temperature on the hydration heat of cement using solution calorimetry. When curing at 20 °C, a lower water-cement ratio resulted in a higher cumulative hydration heat and hydration heat evolution rate at 24 h, but subsequently decreased. A lower water-cement ratio led to a lower cumulative hydration heat when curing at 5 °C and 0 °C. A higher water-cement ratio caused lower cumulative hydration heat when curing at −5 °C. The cumulative hydration heat of the cement paste increased with the curing temperature, and the influence of the negative temperature on the cumulative hydration heat of the cement paste increased with the water-cement ratio. The compound exponential model was used to predict the hydration heat of cement paste maintained above 0 °C. The results obtained by the logarithmic function model are in good agreement with the experimental results for curing at negative temperature.

To improve the properties of ground granulated blast furnace slag (GGBS) and utilize ground granulated blast furnace slag efficiently, this study investigates the effect of fineness on the hydration activity index (HAI) of ground granulated blast furnace slag. The hydration activity index of GGBS with six specific surface areas (SSAs) was characterized by the ratio of compressive strength of the prismatic mortar test block. The particle size distribution of GGBS with different grinding times was tested by laser particle size analyzer. The paste of different specific surface area GGBSs in different curing ages was investigated at the micro level by X-ray diffraction, scanning electron microscope, energy dispersive spectrometer, thermogravimetric scanning calorimeter, and differential scanning calorimeter. The effect of particle distribution of GGBS on the hydration activity index of different curing ages was studied by gray correlation analysis. The results indicated that the compressive strength and hydration activity index increases with the increase of a specific surface area of GGBS at different curing ages. The hydration activity index at different curing ages is almost a linear role for specific surface areas. With the increase in the specific surface area of GGBS, the content of Ca(OH)2 in paste decreases gradually. When GGBS was added into a mortar test block, the hydrate calcium silicate gel in paste changed from a high Ca/Si ratio to a low Ca/Si ratio. The 0&ndash, 10 micron particles of GGBS particle distribution were highly correlated with the hydration activity index at different curing ages.

Based on the thermodynamic equilibrium principle and elastic mechanics theory, the mechanical calculation of borehole wall stress under ice-formation. pressure effect is carried out for the water saturation, condition of cement mortar closed pore. The pore configuration in the cement mortar can be approximated as spherical or cylindrical. A micro-mechanics calculation model is established The borehole wall inner and outer surface tensile stress is deduced in different pores under the ice-formation pressure effect. For the cement mortar component, the borehole wall stress of spherical and cylindrical pores is calculated at -20°C. Results show that the spherical pore is more constant than the cylindrical pore under the same ice-formation pressure effect. The borehole wall tensile stress of the spherical pore is much smaller than that of the cylindrical one, which is advantageous for frost resistance. Finally, according to the theoretic calculation method, the pore configuration, radius, borehole thickness and freezing temperature are the main factors in borehole wall tensile stress, as shown by the parameter analysis. Knowledge of useful practices in freezing and thawing destruction mechanisms of concrete in cement mortar can contribute to concrete durability design theories in bridge engineering.

The compressive strength of the contrast mortars and test mortars at different curing temperatures at different ages were tested. Effect of curing temperature on the strength of the test mortars and the contrast mortars was analyzed. The relative activity index and absolute activity index of the silica fume were studied. The mercury porosimetry method was used to test the pore structure of mortar specimens, and the improving effect of silica fume on the pore structure of mortar specimens under different curing temperatures was analyzed. The results show that with the increase of age, the decrease of curing temperature will cause the strength of mortar specimens to slow down. At the 3d and 7d ages, with the decrease of curing temperature, the absolute activity value of silica fume gradually increases. After 7 days of age, with the decrease of curing temperature, the absolute activity of silica fume gradually decreases. With the increase of curing age, the relative activity of silica fume decreases at first and then increases at 20°C and 10°C. The relative activity value of silica fume under the maintenance of 5°C and -3°C increased first and then decreased gradually. The addition of silica fume in the concrete improved the internal pore structure of the specimen, and the effect of curing temperature on the specimen was consistent.