Effect of Fly Ash on Properties of Self-Compacting High Strength Lightweight Concrete

Abstract

IntroductionAs known, self-compacting concrete (SCC) is highly flowable, non-segregating concrete that can spread into place, fill the formwork, and encapsulate the reinforcement without any mechanical consolidation. It doesn't require any vibration for compaction and can flow through narrow spaces without segregation and excessive bleeding [1]. Therefore SCC is one of the greatest innovations of concrete technology. It was introduced in construction industry in early 1990s. Similar to the normal vibrated concrete (NVC), SCC mixtures consist of aggregate, cement, water, admixtures and some mineral additions. Unlike NVC, SCC has high quantity of fillers (eg. silica fume, fly ash, limestone powder etc.) and superplasticizer (high-range water reducing admixture) added to improve its flowing property.As SCC flows under its own weight without or very little use of vibration, it results in saving a lot of labor effort and bring economy to the concreting. Moreover, it can also flow through narrow and complex geometries where the use of vibrator is almost impossible.Use of SCC in construction industry is getting more and more popularity all over the world because of inherited advantages and studies on its hardened properties. SCC can be classified mainly into 3 different types [2]:• powder type;• viscosity type and • combination type The first type has a high amount of powder (all material <0.15 mm) ranging from 550-650 kg/m 3 , which provides the plastic viscosity and thus resistance to segregation whereas the yield point is determined by the addition of suitable superplasticizers. In the second type there is less powder content ranging from 350-450 kg/m 3 . In this type additional minerals or fillers are not used for segregation resistance. An admixture called viscosity modifying agent (VMA) is used to control the segregation, while yield point is controlled by the superplasticizer. The third type has a powder content of 450-550 kg/m 3 , but additionally rheology is controlled by the use of appropriate dosage of VMA and superplasticizer.

Effects of different size of fly ash as cement replacement on self-compacting concrete properties

“…A study from Mushtaq et al [6] was also found the presence of fly ash increased the mechanical properties including compressive, split tensile and flexural strengths off SCC mixtures. The similar study was also reported by Iqbal et al [7] Based on some previous experimental works, this study aims to investigate the effect of different fineness of fly ash sourced from PLTU II North Sulawesi in Amurang. It is expected that finer particles could improve the workability of SCC mixtures based on slump-flow and L-box tests and also contribute the mechanical properties of concrete containing fly ash.…”

Effect of the curing type on the mechanical properties of lightweight concrete with polypropylene and steel fibres

“…The overuse of natural aggregate in the construction sector has harmed the environment in recent decades, and it is estimated that about 7.5 billion tonnes of aggregates are annually consumed by the concrete industry [1][2][3][4][5]. This environmental issue can be somewhat solved by partial replacement of natural aggregates with artificial lightweight aggregates in the building process [6][7][8][9][10]. Although the use of lightweight concrete (LC) dates back to the Roman Empire, modern age artificial lightweight aggregates were produced in the middle of the 20 th century and then they were developed by researchers in the concrete industry [11,12].…”

Libro de Comunicaciones / Livro das Comunicações

“…La mezcla de CAC con ceniza volante [38] indica que el reemplazo de OPC por FA generó un mayor flujo de asentamiento (2,54 % y 2,83 % para los CAC con 35% y 50% de FA respectivamente), menor tiempo en el embudo en V y una relación H2/H1 mayor en comparación con su mezcla de referencia (CAC 100_FA-0), este comportamiento es característico de algunos FA en CAC [43]. También, el uso de FA hizo que el contenido de superplastificante (SP) disminuyera en las mezclas de CAC, comportamiento que coincide con el obtenido en el estudio realizado por Gesoglu et al,…”