Topic
Silica fume
About: Silica fume is a research topic. Over the lifetime, 10177 publications have been published within this topic receiving 173857 citations.
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TL;DR: In this paper, the effects of silica fume, PVA fiber and their combinations on the mechanical properties, microstructure, abrasion resistance and volume stability of cement pastes and/or fly ash concrete were studied experimentally.
Abstract: The effects of silica fume, PVA fiber and their combinations on the mechanical properties, microstructure, abrasion resistance and volume stability of cement pastes and/or fly ash concrete were studied experimentally in this work. The results indicated that the compressive strength and tensile strength of concrete containing both silica fume and PVA fiber were obviously improved compared with the control concrete. The addition of PVA fiber in concrete considerably reduced the drying shrinkage and improved the anti-cracking resistance of cement pastes and concrete, and the abrasion resistance of concrete significantly increased with the addition of silica fume and PVA fiber. These findings have been successfully adopted to guide the design and construction of hydraulic structures in the southwest of China.
105 citations
TL;DR: In this paper, a study was conducted in which a lightweight concrete was processed using ceramic microspheres known as cenospheres as a primary aggregate, and the mechanical properties, including compressive strength, tensile strength, flexural strength and fracture toughness, were tested and cataloged.
Abstract: A study has been conducted in which a lightweight concrete was processed using ceramic microspheres, known as cenospheres, as a primary aggregate. The mechanical properties, including compressive strength, tensile strength, flexural strength and fracture toughness, were tested and cataloged. It was determined that the addition of high volumes of cenospheres significantly lowered the density of concrete but was also responsible for some strength loss. This strength loss was recovered by improving the interfacial strength between the cenospheres and the cement. The interfacial properties were quantified using interfacial fracture mechanics techniques. These techniques were also employed to find a suitable surface modifier with which to improve this interface. The admixture silica fume and the coupling agent Silane™ were found to be suitable candidates and both performed well in small-scale compression testing. Silica fume was eventually isolated as a prime candidate. The concrete produced with this admixture was tested and compared to a concrete with an equal volume fraction of cenospheres. The addition of silica fume improved the compressive strength of cenosphere concrete by 80%, tensile strength by 35%, flexural strength by 60% and fracture toughness by 41%.
105 citations
TL;DR: In this paper, the magic angle spinning (MAS) NMR spectroscopy was used to study the chemical environment of 27Al-bearing phases in Portland cement-based concrete.
105 citations
TL;DR: In this article, the performance of a series of sewer pipe concrete mixtures and cementitious lining mixtures in acid environments was reported, with both acid-soluble and acid-insoluble aggregates and various supplementary cementitious materials (SCM).
Abstract: The paper reports on the performance of a series of sewer pipe concrete mixtures and cementitious lining mixtures in acid environments. Binder types based on ordinary portland cement (OPC) and calcium aluminate cement (CAC) were used, with both acid-soluble and acid-insoluble aggregates and various supplementary cementitious materials (SCM). One series of tests subjected the mixtures to pure mineral acid (hydrochloric acid, pH = 1), using a specially designed dynamic test rig. The other series of tests involved monitoring specimens placed in a live sewer under very aggressive conditions induced by acid-generating bacteria. Under mineral acid attack on concretes with conventional dolomite aggregates, OPC/silica fume concretes displayed best performance, attributed to their densified microstructure coupled with substantially improved ITZ. CAC concretes with dolomite aggregate did not perform any better than similar OPC specimens under these conditions, primarily because of their higher porosity. However, with concretes using synthetic alagTM aggregates in mineral acid testing, CAC/alagTM mixtures performed exceptionally well due to their homogeneous microstructure, inferred absence of an ITZ, and slower dissolution and finer size of alagTM aggregate particles. The dynamic acid test was able to reveal differences in physical and chemical interactions between constituents in concrete mixes. Under biogenic acid conditions in the sewer, CAC concretes clearly outperformed OPC concretes. This is ascribed to the ability of CAC to stifle the metabolism of the acid-generating bacteria, thereby reducing acid generation. Thus the effects of neutralisation capacity and stifling of bacterial activity need to be distinguished in designing concrete mixtures to provide good acid resistance. Relative rates of dissolution of binder and aggregates are also important in overall performance, with uniform rates preferable in order to avoid aggregate fallout.
105 citations
TL;DR: In this paper, the performance of a two-stage approach of using limestone powder (LP) pre-coated crumb rubber and silica fume (SF) to enhance the rubberized cement mortar was investigated.
105 citations