Frost Resistance of Magnesium Oxychloride Cement Mortar Added with Highland Barley Straw Ash

In order to study the influence of highland barley straw ash (HBSA) prepared under certain conditions on the durability of magnesium oxychloride cement mortar (MOCM) under freeze-thaw damage,rapid freeze-thaw cycle tests were carried out firstly.The relative mass evaluation parameters and the relative compressive strength evaluation parameters,which represent the degradation of freeze-thaw resistance,were used as the indices to study the degradation rule of MOCM.Secondly,nuclear magnetic resonance (NMR) tests were carried out on MOCM under different freeze-thaw cycles to analyze the pore diameter changes in the freeze-thaw process.The microstructure of MOCM was tested by Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD) and scanning electron microscopy (SEM),and then the effect mechanism of HBSA on the anti-freezing performance of MOCM was revealed.Finally,the two-parameter Weibull distribution function was used to analyze the reliability of durability degradation of MOCM added with HBSA under freeze-thaw cycles.The specific conclusions are as follows:With the increase of HBSA's addition,the freeze-thaw resistance of MOCM increase firstly and then decrease.When the addition of HBSA is 10%,the decay rate of relative mass evaluation parameters and relative compressive strength evaluation parameters is the slowest,and the frost resistance is the best.The proportion of harmful pores and more harmful pores in MOCM added with 10% HBSA decreases by 25.11% and 21.34%,compared with that without HBSA before and after freeze-thaw cycles.A lot of magnesium silicate hydrate (M-S-H) gels are generated in MOCM with HBSA content of 10%,which fills part of the pores,so that the proportion of harmful pores and more harmful pores is the lowest.The Weibull function can be effectively applied to the reliability analysis of the freeze-thaw cycle of MOCM added with HBSA,and the theoretical results are in good agreement with the experimental results.

Factors affecting the quality of biomass pellet for biofuel and energy analysis of pelleting process

Agricultural biomass residue such as barley,canola,oat and wheat straw has the potential to be used for sustainable production of bio-fuels and offset greenhouse gas emissions.The biomass substrate must be processed and handled in an efficient manner in order to reduce industry’s operational cost as well as meet the requirement of raw material for biofuel production.Biomass has low bulk density,making it difficult and costly to store and transport in its native loose form.Therefore,in this study,an integrated approach to densification of non-treated and steam exploded barley,canola,oat and wheat straw was developed.During this process,the significance of major contributing factors(independent variables such as biomass type,treatment,pressure and grind size)on pellet density,durability and specific energy were determined.It has been found that applied pressure(60.4%)was the most significant factor affecting pellet density followed by the application of steam explosion pre-treatment(39.4%)for lab-scale single pelleting experiments.Similarly,the type of biomass(47.1%)is the most significant factor affecting durability followed by the application of pre-treatment(38.2%)and grind size(14.6%)for pellets manufactured using the pilot-scale pellet mill.Also,applied pressure(58.3%)was the most significant factor affecting specific energy required to manufacture pellets followed by the biomass(15.3%),pre-treatment(13.3%)and grind size(13.2%),which had lower but similar effect on specific energy for lab-scale single pelleting experiments.Overall energy analysis of post-harvest processing and densification of agricultural straw was performed,which showed that a significant portion of original agricultural biomass energy(89%-94%)is available for the production of biofuels.Almost,similar amount of specific energy is required to produce pellets from barley,canola,oat and wheat straw grinds.Customized pellets having steam exploded straw required more energy to manufacture resulting in availability of only 89%of total energy for biofuel production.