Materials and processes for the effective capture and immobilization of radioiodine: A review

A comprehensive overview about the influence of different additives on the properties of alkali-activated slag – A guide for Civil Engineer

Green concrete: Prospects and challenges

This work aims to reveal the effects of silica fume on properties of fly ash based geopolymer under thermal cycles. Geopolymer specimens were prepared by alkali activation of fly ash, which was partially replaced by silica fume at levels ranging from 0% to 30% with an interval of 10%, by mass. Microstructure, residual strength and mass loss of fly ash based geopolymer blended with silica fume before and after exposed to 7, 28 and 56 heat-cooling thermal cycles at different target temperatures of 200 °C, 400 °C and 800 °C were assessed and compared. The experimental results reveal that silica fume addition enhances strength development in geopolymer. Under thermal cycles, the compressive strength of geopolymer decreases, and the compressive strength loss, as well as the mass loss, increases with increasing target temperature. The strength loss is the same regardless of silica fume content after thermal cycles. Microstructure analysis uncovers that pore structure of geopolymer degrades after thermal cycles. The pores of geopolymer are refined by the addition of silica fume. The incorporation of silica fume optimizes the microstructure and improves the thermal resistance of geopolymer. Silica fume increases the strength of the geopolymer and even though the strength loss is the same, the strength after heat cycle exposure is still good.

Compressive strength and microstructure of fly ash based geopolymer blended with silica fume under thermal cycle

Potential use of brick waste as alternate concrete-making materials: A review

Alkali-activated cements and mortars based on blast furnace slag and red clay brick waste

The influence of the fineness, concentration, and chemico-mineralogical composition of limestone on the workability, reaction kinetics, compressive strength, microstructure, and binder gel characteristics of sodium carbonate–based waste-activated waste slag cement pastes was investigated in this work. Alkali-activated slag cements incorporated with limestone, containing 33–100% of calcite, at a content of up to 60% with a 28-day compressive strength of 26.2–48.8 MPa were proposed. The main reaction products of hardened alkali-activated cement pastes and those incorporated with limestone are C S H, CaCO 3 , Na 2 Ca(CO 3 ) 2 ·5H 2 O, and Na 2 CaSiO 4 . “Physically active” limestone does not chemically react with the binder gel but it can improve the physical structure. The higher packing density of mixed cement, without an increase in the water demand, the satisfactory binding strength of limestone with the binder gel lead to the improvement in the physical structure and compressive strength of alkali-activated slag paste.

Influence of limestone content, fineness, and composition on the properties and microstructure of alkali-activated slag cement

Cementitious Materials for Nuclear Waste Immobilization

Incorporation of mineral blending and/or modifying additions which are single- or multi-component materials is one of the main trends in the development of both Portland clinker-based and non-clinker cements. There is an increasing scientific and industrial interest in alkali-activated binders as ecologically and technically promising inorganic materials. Progress in this area is also derived from advances in the technologies of production and processing of a wider range of mineral materials from natural and waste origins, and by constant expansion of the raw materials base of alkali-activated materials. This paper reviews (i) alkali-activated metakaolin-based cements incorporated with mineral supplementary materials from the point of view of the supplementary additions raw materials base, features of reaction products, structure, properties and formation process; (ii) a range and classification of mineral additions to alkali-activated metakaolin cements; (iii) the feasibilities of improving the structure and properties of mixed alkali-activated metakaolin cements.

Reaction products, structure and properties of alkali-activated metakaolin cements incorporated with supplementary materials – a review

The consistent development of the waste-minimisation and recycling-oriented technologies in the most resource- and energy-intensive industries is crucial for sustainable development. Chemical activation based on a non-fired or low-temperature approach for the production of binders from glassy aluminosilicates, including a wide range of wastes and by-products from different industries, is an intensively developing and promising clean technology that finds application in construction and building materials, management of hazardous and nuclear waste, etc. Blended binders are designed using a mixture of mineral materials as a tool, through the regulation of composition and structure, to obtain materials with controlled performance. The resulting materials in turn improve engineering performance and aid the valorisation of different types of wastes and by-products. This is one of the main trends in the development of the modern cement industry, including the alkali activation technology. Coal fly ash is one of the large-tonnage wastes that is effectively converted by alkali activation in binders and compatible with many mineral supplementary materials. This paper reviews (i) the supplementary mineral materials of natural and waste origin from different industries for alkali activated fly ash (class F) cements (AAFA); (ii) the composition, structure, and properties formation process of AAFA incorporated with blending and modifying materials, and (iii) the feasibility for improvement of the structures and properties of mixed AAFA.

Ravil Z. Rakhimov

Papers

Alkali-activated cements and mortars based on blast furnace slag and red clay brick waste

Influence of limestone content, fineness, and composition on the properties and microstructure of alkali-activated slag cement

Cementitious Materials for Nuclear Waste Immobilization

Reaction products, structure and properties of alkali-activated metakaolin cements incorporated with supplementary materials – a review

Toward clean cement technologies: A review on alkali-activated fly-ash cements incorporated with supplementary materials