Ettringite

About: Ettringite is a research topic. Over the lifetime, 2702 publications have been published within this topic receiving 67056 citations. The topic is also known as: woodfordite.

Cement additive comprising calcium sulfo-aluminate, an organic adhesive, a foaming agent, and a dispersing agent

Abstract: A cement additive consisting of 100 parts by weight of a mineral consisting mainly of calcium sulfo-aluminate, which forms ettringite having a high content of sulfate through hydration, 0.1 to 2.0 parts by weight of an organic adhesive, 0.005 to 0.5 part by weight of a blowing agent and 1.0 to 6.0 parts by weight of a dispersing agent is suitable for grout. This cement additive is preferred to be added with 0.5 to 10.0 parts by weight of an accelerating agent.

Investigation of hydration products of fly ash–slag pastes

Abstract: The paper presents the results of the research identifying the hydration products present in hardened fly ash–slag pastes considered as alternative non-clinker binder. Thermal analysis (TG/DTG), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used as complementary methods. The pastes contained the binder made of two components: fly ash from circular fluidized bed combustion of brown coal and ground granulated blast furnace slag. The components were mixed accordingly to five formulas differing in proportions, but with constant water/binder ratio (w/b = 0.5). No chemical activators were used to initiate the binding reaction of blast furnace slag. The results of thermal analysis, IR spectroscopy and scanning electron microscopy as well as the increase of compressive and flexural strength in time revealed the progression of hydration process in time and formation of products similar to ones present in hardened cement pastes. SEM observations of pastes after 90 days of curing showed fibrous (type I) and similar to honeycomb form of C–S–H phase, ettringite and calcium aluminates.

Experiment Analysis of Concrete’s Mechanical Property Deterioration Suffered Sulfate Attack and Drying-Wetting Cycles

Abstract: The mechanism of concrete deterioration in sodium sulfate solution is investigated. The macroperformance was characterized via its apparent properties, mass loss, and compressive strength. Changes in ions in the solution at different sulfate attack periods were tested by inductively coupled plasma (ICP). The damage evolution law, as well as analysis of the concrete’s meso- and microstructure, was revealed by scanning electron microscope (SEM) and computed tomography (CT) scanning equipment. The results show that the characteristics of concrete differed at each sulfate attack period; the drying-wetting cycles generally accelerated the deterioration process of concrete. In the early sulfate attack period, the pore structure of the concrete was filled with sulfate attack products (e.g., ettringite and gypsum), and its mass and strength increased. The pore size and porosity decreased while the CT number increased. As deterioration progressed, the swelling/expansion force of products and the salt crystallization pressure of sulfate crystals acted on the inner wall of the concrete to accumulate damage and accelerate deterioration. The mass and strength of concrete sharply decreased. The number and volume of pores increased, and the pore grew more quickly resulting in initiation and expansion of microcracks while the CT number decreased.