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

To evaluate the effectiveness of lithium-based products to counteract alkali-silica reaction (ASR), a total of 87 concrete mixtures were made incorporating 12 reactive aggregates of various types and degrees of ASR, and using various dosages of LiNO 3 and Li glass in combination or not with supplementary cementing materials (SCM) The concrete prisms were tested at 38 °C (100 °F), according to CSA A232-14A or ASTM C 1293, and also at 60 °C (140 °F) to evaluate the possibility of accelerating the testing procedure Using LiNO 3 at the [Li]/[Na + KJ ratio of 074 recommended by the manufacturer, satisfied the 2-year 004% expansion limit criterion (CSA A232-28A) at 38 °C (100 °F) for six aggregates; three aggregates required a ratio between 074 and 111, while a ratio 111 was not effective with the other three aggregates The lithium glass was not effective The ternary silica fume/slag cement tested was effective and the fly ashes and slag as well provided they were in sufficient quantities and they had a proper composition Most LiNO 3 -SCM combinations did not show significant synergetic effect The required LiNO 3 dosage is not related to the aggregate reactivity The 6-month expansion at 60 °C (140 °F) correlated well with the 2-year expansion at 38 °C (100 °F) for the control and SCM mixtures, but not for the LiNO 3 mixtures

Effectiveness of Lithium-Based Products in Concrete Made with Canadian Natural Aggregates Susceptible to Alkali-Silica Reactivity

Different methods were investigated to determine the amount of alkalies released by various supplementary cementing materials (SCM) available for alkali-silica reactivity. Two American Society for Testing and Materials (ASTM) methods were applied: ASTM C 114 (water-soluble alkalies) and ASTM C 311 (available alkalies). The ASTM C 114 method gives only the amount of rapidly soluble alkali in the form of alkali salts (sulfates and chlorides). The ASTM C 311 standard and modified methods give values between 40 and 100 percent of total alkalies; in most cases, both methods clearly overestimate the percentage of alkalies available from supplementary cementing materials, probably because a large proportion of alkalies entrapped in secondary hydrates are released when the samples are thoroughly washed with water at the end of the tests. Indeed, for all good SCM tested, the results from pore solution chemistry suggest that more alkalies are entrapped in secondary hydrates than released from SCM in the pore solution (negative contributions). These results are in good agreement with expansion test on concretes made with the same SCM and two very reactive aggregates. The pore solution extraction method appears to be the best method to evaluate the balance between the alkalies released by SCM in the pore solution and those entrapped in reaction hydrates.

Available Alkalies From Supplementary Cementing Materials

Application of the NBRI accelerated mortar bar test to siliceous carbonate aggregates produced in the St. Lawrence lowlands (Quebec, Canada) part 1: Influence of various parameters on the test results

In-situ monitoring of concrete deformations and movements is the best way to assess the current expansion of concrete members affected by alkali-silica reactivity (ASR). However, laboratory tests on cores are less expensive and more rapid, and are commonly used to assess the potential for further expansion due to ASR. The risk of expansion and damage due to ASR can be reasonably assessed in the laboratory from: (1), the inherent expansivity of the concrete under study, which is determined by testing core samples in air at 100% RH and 38°C; (2), the residual absolute reactivity of the aggregates present in the concrete under study, which can be determined by testing core samples in 1N NaOH solution at 38°C or, even better for coarse aggregates, by testing aggregates extracted from cores through the concrete prism test CSA A23.2-14A or ASTM C 1293; (3), the amount of alkalies that are still active in the concrete, i.e. in the pore solution, which is estimated by a hot-water extraction method on ground concrete, and (4), humidity, (5), temperature, and (6), stress conditions (confinement, reinforcement, pretensioning, postensioning) in service. The individual risk indices corresponding to each of the above parameters are combined to determine the potential rate of ASR expansion of concrete members in service, either already affected by ASR or not.

Laboratory assessment of the potential rate of ASR expansion of field concrete

Application of the NBRI accelerated mortar bar test to siliceous carbonate aggregates produced in the St. Lawrence Lowlands (Quebec, Canada) part 2: Proposed limits, rates of expansion, and microstructure of reaction products

Marc-André Bérubé

Papers

Effectiveness of Lithium-Based Products in Concrete Made with Canadian Natural Aggregates Susceptible to Alkali-Silica Reactivity

Available Alkalies From Supplementary Cementing Materials

Application of the NBRI accelerated mortar bar test to siliceous carbonate aggregates produced in the St. Lawrence lowlands (Quebec, Canada) part 1: Influence of various parameters on the test results

Laboratory assessment of the potential rate of ASR expansion of field concrete

Application of the NBRI accelerated mortar bar test to siliceous carbonate aggregates produced in the St. Lawrence Lowlands (Quebec, Canada) part 2: Proposed limits, rates of expansion, and microstructure of reaction products