Study On Mix Proportion And Performance Of Desert Sand Foam Concrete

In recent years,China has paid more and more attention to building energy conservation.In order to get rid of the crisis caused by building energy,higher requirements are put forward for the rational development and utilization of resources.At the same time,the rational use of solid waste and undeveloped natural resources has become another way of energy saving.Desert sand is a large amount of natural resources.The use of desert sand to make foam concrete can effectively reduce the degree of desertification and protect the ecological environment.Moreover,desert sand is alkaline,which is more conducive to the generation of bubbles in foam concrete slurry.In this study,27.5%hydrogen peroxide solution was used as foaming agent,calcium stearate was used as foam stabilizer,desert sand powder,42.5 ordinary Portland cement and sulphoaluminate cement were the main materials for making foamed concrete.The conclusions are as follows:（1）The optimum range and dosage of desert sand powder,water-binder ratio,polypropylene fiber,calcium stearate and 27.5%hydrogen peroxide solution were obtained by single mixing test.The replacement rate of desert sand powder was 10%～20%.The water-binder ratio is 0.57～0.59;polypropylene fiber length of 6mm;polypropylene fiber content is 0.25%～0.35%;the content of calcium stearate is 1.5%;the dosage of 27.5%hydrogen peroxide solution is 3%.（2）Imagine Pro Plus was used to test the pore shape factor and porosity.It was found that the porosity increased with the increase of desert sand powder substitution rate and water-binder ratio.When the desert sand powder substitution rate was 10%and the water-binder ratio was 0.58,the pore shape factor reached the minimum value.The increase of polypropylene fiber content makes the porosity increase first and then decrease.（3）Based on the orthogonal test method,desert sand powder replacement rate of10%,water-binder ratio of 0.59,6mm polypropylene fiber content of 0.3%to obtain the best mix,physical properties to meet the《foam concrete》（JG/T266-2011）requirements.（4）The X-ray diffractometer was used to analyze the foam concrete under different desert sand powder substitution rates and the hydration products of the optimal group of orthogonal test and the intuitive analysis of the optimal group and the worst group.The Ca（OH）₂crystallinity of the optimal group of orthogonal test was higher and the reaction degree was better.The Si O₂crystallinity of the worst group of intuitive analysis was higher,which hindered the process of cement hydration reaction.Scanning electron microscopy was used to observe the apparent morphology and compactness of the pore structure and pore wall of foam concrete under different desert sand powder replacement rates and foam concrete under different polypropylene fiber content.It was concluded that the density of the pore structure was higher when the desert sand powder replacement rate was 10%,and the microscopic morphology was better.When the content of polypropylene fiber is 0.3%,the bonding performance of polypropylene fiber in foam concrete is strong,and the spatial network structure is formed to improve the compressive strength of foam concrete.