Metakaolin and calcined clays as pozzolans for concrete: a review
TL;DR: The use of metakaolin (MK) as a pozzolanic material for mortar and concrete has received considerable attention in recent years as mentioned in this paper, which is part of the widely spread attention directed towards the utilisation of wastes and industrial by-products in order to minimise Portland cement consumption, the manufacture of which being environmentally damaging.
Abstract: The utilisation of calcined clay, in the form of metakaolin (MK), as a pozzolanic material for mortar and concrete has received considerable attention in recent years. This interest is part of the widely spread attention directed towards the utilisation of wastes and industrial by-products in order to minimise Portland cement (PC) consumption, the manufacture of which being environmentally damaging. Another reason is that mortar and concrete, which contain pozzolanic materials, exhibit considerable enhancement in durability properties. This paper reviews work carried out on the use of MK as a partial pozzolanic replacement for cement in mortar and concrete and in the containment of hazardous wastes. The literature demonstrates that MK is an effective pozzolan which causes great improvement in the pore structure and hence the resistance of the concrete to the action of harmful solutions.
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TL;DR: The use of silica-rich SCMs influences the amount and kind of hydrates formed and thus the volume, the porosity and finally the durability of these materials.
1,920 citations
TL;DR: In this paper, the authors present the work carried out on the chemical reaction, the source materials, and the factor affecting geopolymerization, and demonstrate that certain mix compositions and reaction conditions such as Al2O3/SiO2, alkali concentration, curing temperature with curing time, water/solid ratio and pH significantly influences the formation and properties of a geopolymers.
Abstract: Geopolymerization is a developing field of research for utilizing solid waste and by-products. It provides a mature and cost-effective solution to many problems where hazardous residue has to be treated and stored under critical environmental conditions. Geopolymer involves the silicates and aluminates of by-products to undergo process of geopolymerization. It is environmentally friendly and need moderate energy to produce. This review presents the work carried out on the chemical reaction, the source materials, and the factor affecting geopolymerization. Literature demonstrates that certain mix compositions and reaction conditions such as Al2O3/SiO2, alkali concentration, curing temperature with curing time, water/solid ratio and pH significantly influences the formation and properties of a geopolymer. It is utilized to manufacture precast structures and non-structural elements, concrete pavements, concrete products and immobilization of toxic metal bearing waste that are resistant to heat and aggressive environment. Geopolymers gain 70% of the final strength in first 3–4 h of curing.
1,078 citations
TL;DR: In this paper, the coupled substitution of metakaolin and limestone in Portland cement (PC) was investigated and the mechanical properties were studied in mortars and the microstructural development in pastes by X-ray diffraction, thermogravimetry analysis, mercury intrusion porosimetry and isothermal calorimetry.
763 citations
TL;DR: In this paper, the decomposition of three clayey structures (kaolinite, illite and montmorillonite) when thermally treated at 600 degrees C and 800 degrees C was investigated and the effect of this treatment on their pozzolanic activity in cementitious materials.
600 citations
TL;DR: In this paper, the authors compared the mechanical and durability properties of high performance metakaolin and silica fume concretes to their microstructure characteristics, and found that the effect of metakaolins on the interfacial porosity is discussed based on test results.
531 citations
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Book•
01 Jan 1964
TL;DR: An international symposium on the chemistry of cements, organized by the Royal Swedish Institute for Engineering Research and the Swedish Cement Association, was held in Stockholm on July 6-8 and attended by representatives from Great Britain, Canada, the United States and many of the European countries.
Abstract: AN international symposium on the chemistry of cements, organized by the Royal Swedish Institute for Engineering Research and the Swedish Cement Association, was held in Stockholm on July 6-8 and attended by representatives from Great Britain, Canada, the United States and many of the European countries. A short tour was arranged to precede the meeting, to enable visitors from abroad to see the cement and concrete industry in southern and central Sweden.
545 citations
TL;DR: In this paper, the role of metakaolin (MK) in enhancing the strength of concrete is reviewed and principal mechanisms identified, and the observed results establish that there is an optimum OPC replacement level of 20 wt% MK and that the contribution which MK makes to strength is restricted beyond 14 days.
540 citations
Book•
01 May 1996
TL;DR: The sources of production and utilization rate chemical and physical characteristics mechanisms by which mineral admixtures improve properties of concrete are discussed in this paper, where they select materials and mixture proportions according to standard specifications.
Abstract: Sources of production and utilization rate chemical and physical characteristics mechanisms by which mineral admixtures improve properties of concrete effect of mineral admixtures on properties of fresh concrete effect of mineral admixtures on properties of hardened concrete durability aspects of concrete containing mineral admixtures selection of materials and mixture proportions standard specifications. (Part contents).
400 citations
TL;DR: A survey of the reaction series of metakaolin can be found in this paper, where the authors provide the necessary historical background for a new approach to their solution, and the present survey brings these problems into sharp focus.
Abstract: This reaction series has been a subject of extensive investigation since the work of Le Chatelier in 1887. Nevertheless, major problems have remained concerned with the nature of metakaolin, the manner in which it transforms into a spinel-type phase and mullite, and the relation of this spinel-type phase to mullite. The present survey brings these problems into sharp focus and provides the necessary historical background fora new approach to their solution.
275 citations
TL;DR: In this paper, the effect of silica fume (SF), metakaolin (MK), fly ash (FA) and ground granulated blast-furnace slag (GGBS) on the setting times of high-strength concrete has been investigated using the penetration resistance method (ASTM C 403).
Abstract: The effect of silica fume (SF), metakaolin (MK), fly ash (FA) and ground granulated blast-furnace slag (GGBS) on the setting times of high-strength concrete has been investigated using the penetration resistance method (ASTM C 403). In addition, the effect of a shrinkage-reducing admixture (SRA) on the setting times of normal and high-strength concrete was also studied. The setting times of the high-strength concrete were generally retarded when the mineral admixtures replaced part of the cement. While the SRA was found to have negligible effect on the setting times of normal strength concrete, it exhibited a rather significant retarding effect when used in combination with superplasticiser in high-strength concrete. The inclusion of GGBS at replacement levels of 40% and greater resulted in significant retardation in setting times. In general, as replacement levels of the mineral admixtures were increased, there was greater retardation in setting times. However, for the concrete containing MK, this was only observed up to a replacement level of 10%.
266 citations