Research On Preparation And Performance Of Biomass Ash Autoclaved Aerated Concrete

Biomass power plant ash?abbreviated as"biomass ash"?refers to an industrial waste discharged from a power plant that utilizes the biomass energy it possesses to generate electricity.Unlike other industrial solid waste,the alkali of biomass ash is very strong.It contains rich mineral nutrients such as potassium,silicon,calcium and so on.In recent years,research on the solid wastes such as the recycling of biomass ash has been an important task for workers.This paper aims to take biomass ash as the research object,make use of biomass ash by hydrothermal synthesis and autoclave curing methods,and research the combination of biomass ash,fly ash and other solid waste to prepare B05 grade biomass ash aerated concrete blocks.In this paper,the mechanical properties and thermal conductivity of aerated concrete prepared from two kinds of biomass ash were studied experimentally.And the two kinds of biomass ash aerated concretes were characterized by XRD and FESEM.The results showed that the absolute dry densities of the aerated concrete prepared from two kinds of biomass ash gradually increased with the increase of the calcium to silicon ratio,and the compressive strength,flexural strength increased first and then decreased.Both aerated concretes reach peak strength when the calcium to silicon ratio is in the range of 0.80 to 0.86.Under the condition of maximum compressive strength of both biomass ash aerated concretes,the thermal conductivity is better than the national standard of B05 grade aerated concrete block(0.14W·m^-1·K^-1).In addition,the morphology of hydration products of both biomass ash aerated concrete transfer from needle-like structure to sheet-like structure steadily.The influence of different particle size distribution of biomass ash on the physical and mechanical properties,hydration products,pore structure and microstructure of aerated concrete were also researched experimentally.The results show that the wet milling process can further refine the biomass ash,improve the reactivity of the biomass ash,and promote the effective implementation of the hydrothermal reaction.When milling time is 0.5 h,the strength for seven days of the biomass ash block can be the highest,up to 4.14 MPa,which is an increase of 17.95%compared to that of non-wet milling.The most probable pore diameter and average pore size of biomass ash aerated concrete block becomes smaller,the total pore volume is the same,and the internal pore structure of the block is more denser.Moreover,all the blocks generated platy tobermorite phase.The quartz phase tends to disappear as the ball milling time increases,and the peak strength of the C-S-H phase remains almost the same as before.Last but not least,experiment studied the adding of admixture on the performance improvement of biomass ash aerated concrete.The results show that the incorporation of 5%polyvinyl alcohol solution can effectively improve the gas generation process of the aerated concrete,and make the pore structures of biomass ash aerated concrete block have uniform pore size distribution.Sodium dodecyl sulfate?SDS?can assist aluminum in foaming,which increases pore diameter of biomass ash aerated concrete.Polycarboxylate water reducer can effectively improve the fluidity of the slurry mixture and increase the compressive strength of biomass ash aerated concrete block.