Performance Optimization Of Lightweight Aggregate Concrete Mixture

Components are the key to the development of construction industry and the lightweight aggregate concrete is the main material to realize the building industrial.In order to prepare the parts suitable for the development of industrial construction,it is necessary to prepare light aggregate concrete suitable for industrial construction according to the characteristics of lightweight aggregate concrete and the requirements of building industrial parts.In this paper,we focus on the problem of the whole preparation process of the lightweight aggregate concrete from the formula design to the stripping.The research content is set as the issues of the floating problem of the lightweight aggregate concrete,the mixing ratio design and the effect of applied voltage.As for the floating problem for light aggregate concrete,through the force analysis,we find the main factors affecting the floating and solve those problems by controlling the viscosity.According to the ordinary concrete mix method,equal volume replacement principle is suitable for lightweight aggregate concrete mix to design simple and convenient scheme.In the light aggregate concrete,the single kind of component mineral admixture(fly ash,metakaolin,steel slag)was added.When the content was 10%,the compressive strength of the concrete reached the maximum at 3d,7d and 28d.When the two kinds of mineral admixtures were blended,the results showed that the compressive strength of concrete was the best when the fly ash and metakaolin were 2:1 and the total content was 10%.In this case,the compressive strength of the concrete is 35MPa,which increased by 200%compared to the concrete without mineral admixture.The addition of fly ash and metakaolin can not only fill the pores of concrete,but also improve the contact surface between aggregate and cement slurry,and change the morphology and quantity of ettringite,which can improve the compressive strength.Imposing an applied voltage to the concrete can accelerate the hydration of the cement,leading to rapid stripping.With the increase of the applied voltage,the hydration speed of the cement is getting faster.When the applied voltage is too large,the 3d intensity will increase rapidly,while the 28d intensity will decrease to a large extent.When the applied voltage is too small,the 3d intensity is rarely increased,while the 28d intensity will appear steady growth.XRD and SEM show that the applied voltage changes the morphology and the content of ettringite.When the voltage is too small,the ettringite showed a fibrous structure,offering little strength.When the voltage is too high,ettringite showed a large rod-like structure and large cracks in the surface,leading to rapid decline in late strength.When the applied voltage is 18V,the morphology of ettringite exhibit a cross-linked state,and the 3d and 28d intensity are at a high level.Therefore,18V applied voltage is the best pressure of the cement.Comparied with Portland cement,sulphoaluminate cement commonly used in emergency repair works showed a similar law.Results showed that 25V is the best applied voltage to accelerate the hydration of sulphoaluminate cement at low temperature.The early strength(1-7d)and late strength(28d)both present high level.Low-voltage can accelerate the hydration of sulphoaluminate cement and obtain finer ettringite,which will increase the strength of cement in the middle and late stages.High voltage accelerates the hydration of sulphoaluminate cement,thus,the early strength of cement will be significantly improved.But late,sulphoaluminate cement mortar will expand,resulting in rapidly decline in the late strength.Voltage changes will affect the hydration process of sulphoaluminate cement and morphology of ettringite,but will not generate new material generation.