Supplementary cementitious materials

Scanning electron microscopy and mercury intrusion porosimetry are used in parallel to identify the structure of a medium sensitivity Champlain clay. The clay structure is observed firstly on intac...

Study of the structure of a sensitive Champlain clay and of its evolution during consolidation

This paper examines the relationship between the microstructure and engineering properties of cement-treated marine clay. The microstructure was investigated using x-ray diffraction, scanning electron microscopy, pH measurement, mercury intrusion porosimetry, and laser diffractometric measurement of the particle size distribution. The engineering properties that were measured include the water content, void ratio, Atterberg limit, permeability, and unconfined compressive strength. The results indicate that the multitude of changes in the properties and behavior of cement-treated marine clay can be explained by interaction of four underlying microstructural mechanisms. These mechanisms are the production of hydrated lime by the hydration reaction which causes flocculation of the illite clay particles, preferential attack of the calcium ions on kaolinite rather than on illite in the pozzolanic reaction, surface deposition and shallow infilling by cementitious products on clay clusters, as well as the presence of water trapped within the clay clusters.

Physicochemical and engineering behavior of cement treated clays

http://cec.sut.ac.th/download/published/CBM-micro.pdf

Analysis of strength development in cement-stabilized silty clay from microstructural considerations

Utilization and efficiency of ground granulated blast furnace slag on concrete properties – A review

The pH of the pore solution existing within concretes or lime-treated soils normally exceeds 12. When exposed to a solution witl a pH over 10, several rock-forming and soilforming minerals are unstable, and dissolve with or without precipitation, depending on the nature and concentration of species in solution. In concrete, made with a typical cement containing 0.7a/o to l9o alkalis, after a few days, the composition of the liquid phase is dominated by sodium, potassium and hydroxide ions. In this study, the behavior of several common minerals in a pure sodium hydroxide solution was evaluated by the means of two experiments. First, mineral fragments were immersed in a lN NaOH solution at 23oC for 265 days, then at 80oC for 7 days. The specimens were regularly analyzed with a SEM-EDX system. Secondly, the release of silica by silicate minerals in a lN NaOH solution was measured by means of the Chemical Method ASTM C 289 test (80'C, 24 hours). Of all rhe silicate minerals tested, the microcryslalline variety of silica, chert, was the most unstable phase. Significant quantities of silica also were released by quartz and feldspars. Iron and magnesium silicates were found to be the mosr stable phases in the NaOH solution. Among the other minerals investigated, dolomite, siderite and gypsum are classified as highly reactive in the alkaline solution.

Behavior of common rock-forming minerals in a strongly basic NaOH solution

The development of wood treatments is of increasing industrial importance. A novel technique for improving the properties of lodgepole pine and white pine through modification of the microstructure is described. The present investigation is devoted to the synthesis and determination of in situ parameters of citric acid and glycerol based polymers for wood impregnation. This solvent free approach is environmentally friendly and achieved through an esterification condensation reaction under acidic conditions. Crude glycerol and citric acid reactants were cross-linked via a curing process at 160 °C creating a polymer with only water as the byproduct. The ester bonds and crosslinking levels were controlled using different catalysts and citric acid contents and related to the reaction time and temperature. The nature of bonding within the polymers and at the wood cell walls was determined by FT-IR analysis. The thermal properties such as glass transition temperature (Tg) were studied using TGA/DSC and the effect of citric acid content and catalyst type determined. Dimensional stability of impregnated wood samples improved above 50% for each sample with HCl and p-TSA catalysts compared to control samples. FTIR spectra were studied to show the presence of the ester linkages of the polymer in situ at the wood cell walls. Bonding between the polymer and wood macromolecules were observed by scanning electron microscopy and interpreted as evidence of chemical bonds at the wood cells. When prepared using a catalyst, the polymer was intimately incorporated into wood structure significantly improving the substrate dimensional stability. Enhanced stability makes this approach of particular interest for exterior wood products especially as a green renewable option for the wood industry.

Determination of In Situ Esterification Parameters of Citric Acid-Glycerol Based Polymers for Wood Impregnation

Laboratory and field investigations of the influence of sodium chloride on alkali-silica reactivity

The expansion attained by a concrete affected by alkali-silica reaction (ASR) is an important parameter in the evaluation of the corresponding structure. In part I, relationships were established i...

Evaluation of the expansion attained to date by concrete affected by alkali–silica reaction. Part III: Application to existing structures

In the province of Quebec, due to the particular geology and the historic use of high-alkali cements, a large number of concrete structures are affected by alkali-silica reactivity (ASR). Consequen...

Marc-André Bérubé

Papers

Behavior of common rock-forming minerals in a strongly basic NaOH solution

Determination of In Situ Esterification Parameters of Citric Acid-Glycerol Based Polymers for Wood Impregnation

Laboratory and field investigations of the influence of sodium chloride on alkali-silica reactivity

Evaluation of the expansion attained to date by concrete affected by alkali–silica reaction. Part III: Application to existing structures

Alkali-aggregate reactivity in Québec (Canada)