scholarly journals Influence of component fineness on hydration and strength development in ternary slag-limestone cements

2019 ◽  
Vol 4 ◽  
pp. 81-88 ◽  
Author(s):  
Samuel Adu-Amankwah ◽  
Susan A Bernal Lopez ◽  
Leon Black
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Cementitious Materials ◽  
Particle Packing ◽  
Simultaneous Optimization ◽  
Strength Development ◽  
Heat Of Reaction ◽  
Hydration Kinetics ◽  
Compressive Strength Development ◽  
Furnace Slag

The quest for sustainable alternatives to Portland cement has led to the exploration of a range of materials or their combinations, often with the aim of exploiting synergies in reactions or particle packing to maximize performance. Simultaneous optimization of both presents a viable option to increase the efficiency of cementitious materials. The objective of this study was to evaluate the effect of varying the fineness of the constituents in ternary blends of CEM I – granulated ground blast furnace slag (GGBS) - limestone on hydration kinetics and strength development. Eight (8) ternary cement mixes were tested at 0.5 water/binder (w/b) ratio. Hydration was followed by isothermal conduction calorimetry and setting time. In addition, X-ray powder diffraction, thermogravimetric analysis and compressive strength development up to 180 days of curing were assessed. The efficiency associated with changing the fineness of each component was evaluated in terms of the net heat of reaction and compressive strength. The results show that fine CEM I is critical for hydration at early age, and this is reflected in the compressive strength accordingly. The benefits associated with finer GGBS and similarly limestone depend on the fineness of the other constituents in the blend. Optimization of these should consider the inter-dependencies in terms of kinetics and microstructure development.

scholarly journals Influence of Mechanical and Mineralogical Activation of Biomass Fly Ash on the Compressive Strength Development of Cement Mortars

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6654
Author(s):  
Jakub Popławski ◽  
Małgorzata Lelusz
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Cement Mortar ◽  
Setting Time ◽  
Green Energy ◽  
Biomass Combustion ◽  
Strength Development ◽  
Compressive Strength Development ◽  
Biomass Fly Ash

Biomass combustion is a significant new source of green energy in the European Union. The adequate utilization of byproducts created during that process is a growing challenge for the energy industry. Biomass fly ash could be used in cement composite production after appropriate activation of that material. This study had been conducted to assess the usefulness of mechanical and physical activation methods (grinding and sieving), as well as activation through the addition of active silica in the form of silica fume, as potential methods with which to activate biomass fly ash. Setting time, compressive strength, water absorption and bulk density tests were performed on fresh and hardened mortar. While all activation methods influenced the compressive strength development of cement mortar with fly ash, sieving of the biomass fly ash enhanced the early compressive strength of cement mortar. The use of active silica in the form of silica fume ensured higher compressive strength results than those of control specimens throughout the entire measurement period.

scholarly journals Limestone and Calcined Clay-Based Sustainable Cementitious Materials for 3D Concrete Printing: A Fundamental Study of Extrudability and Early-Age Strength Development

2019 ◽  
Vol 9 (9) ◽  
pp. 1809 ◽  
Author(s):  
Chen ◽  
Li ◽  
Chaves Figueiredo ◽  
Çopuroğlu ◽  
Veer ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Cementitious Materials ◽  
Strength Test ◽  
Test Method ◽  
Strength Development ◽  
Early Age ◽  
Ambient Conditions ◽  
Calcined Clay ◽  
Green Strength

The goal of this study is to investigate the effects of different grades of calcined clay on the extrudability and early-age strength development under ambient conditions. Four mix designs were proposed. Three of them contained high, medium, and low grades of calcined clay, respectively, and one was the reference without calcined clay. In terms of extrudability, an extrusion test method based on the ram extruder was introduced to observe the quality of extruded material filaments, and to determine the extrusion pressure of tested materials at different ages. For evaluating the very early-age strength development, the penetration resistance test, the green strength test, and the ultrasonic pulse velocity test were applied. Furthermore, the mechanical properties of the developed mix designs were determined by the compressive strength test at 1, 7 and 28 days. Finally, the main finding of this study was that increasing the metakaolin content in calcined clay could significantly increase the extrusion pressures and green strength, shorten the initial setting time and enhance the compressive strength at 1, 7, and 28 days.

scholarly journals Effect of Bacillus cohnii on Some Physicomechanical and Microstructural Properties of Ordinary Portland Cement

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Ngari Reginah Wangui ◽  
Joseph Karanja Thiong’o ◽  
Jackson Muthengia Wachira
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Microstructural Analysis ◽  
Strength Development ◽  
Microstructural Properties ◽  
Calcite Precipitation ◽  
Strength Tests ◽  
Compressive Strength Development ◽  
Sustainability Challenges ◽  
Cement Setting

Cement-made materials face durability and sustainability challenges. This is majorly caused by the presence of cracks. Cracking affects the mechanical strength of cement-based materials. Microbiologically induced calcite precipitation (MICP) has been found to enhance compressive strength, thus enhancing on the mechanical and durability properties of these materials. This paper presents the findings of a study conducted to investigate the effect of Bacillus cohnii on compressive strength development of OPC mortar prisms and the effect of Bacillus cohnii on cement setting time and soundness. Microbial concentration of 1.0 × 107 cells·ml−1 was used. Compressive strength tests analyses were carried out for each category of mortar prisms. Compressive strength tests were carried out on the 2nd, 7th, 14th, 28th, 56th, and 90th day of curing in distilled water and microbial solutions. All microbial mortars exhibited a greater compressive strength compared to the control with the highest observed at 90 days. Highest percentage gain in compressive strength was observed at 90 days which is 28.3%. Microstructural analysis was carried out using a scanning electron microscope (SEM) after 28 days of curing. The results indicated the presence of calcium carbonate and more calcium silicate hydrate (CSH) deposits on the bacterial mortars. The bacteria did not have an effect on cement soundness. Setting time was significantly accelerated.

scholarly journals Rapid Indicators in Detecting Variation of Fly Ash for Making HVFA Concrete

2015 ◽  
Vol 815 ◽  
pp. 153-157 ◽  
Author(s):  
Antoni ◽  
Rianto Gunawan ◽  
Djwantoro Hardjito
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plants ◽  
Water Solution ◽  
Setting Time ◽  
Cementitious Materials ◽  
Strength Development ◽  
Quick Method ◽  
Alternative Material

The use of fly ash as an alternative material for cement substitute in concrete mix already a common practice nowadays. However, as a waste material, fly ash varies in quality and condition, as shown by variation of its fineness, specific gravity, Loss on Ignition (LOI) and also on its chemical composition. By measuring the acidity (pH) of the fly ash in water solution, percentage of mass retained on 45 μm sieve, and superplasticizer demand of the fly ash, we can develop a quick estimation of the quality of fly ash. This study aims to investigate a quick method to estimate the quality of fly ash by measuring the physical and chemical pointers, as indicator for its properties and the effect on the setting time and compressive strength of mortar. Fly ash content was varied from 0-70% of the total mass of cementitious materials to make HVFA mortar. Fly ashes were obtained from four power plants in Indonesia. Tests conducted were material characterization, setting time, temperature rise, and compressive strength of mortar at different ages. Different fly ash quality can be shown by the fast pointers; namely pH, superplasticizer demand and % retained on 45 μm sieve. Setting time and strength development were affected by the different properties of fly ash.

scholarly journals The influence of calcium sulfate content on the hydration of belite-calcium sulfoaluminate cements with different clinker phase compositions

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Maruša Mrak ◽  
Frank Winnefeld ◽  
Barbara Lothenbach ◽  
Sabina Dolenec
Keyword(s):  
Compressive Strength ◽  
Calcium Sulfate ◽  
Pore Solution ◽  
Bound Water ◽  
Strength Development ◽  
Hydration Kinetics ◽  
Calcium Sulfoaluminate ◽  
Molar Ratios ◽  
Degree Of Reaction ◽  
Compressive Strength Development

AbstractThe influence of different amounts of gypsum on the hydration of a belite-rich and a ye'elimite-rich belite-calcium sulfoaluminate clinker (BCSA) was investigated. The hydration kinetics, phase assemblages and compressive strength development of cements prepared using ye’elimite/ calcium sulfate molar ratios of 1, 1.5 and 2 were studied. Besides ettringite and monosulfate, aluminium hydroxide, strätlingite, C−S−H, iron-containing siliceous hydrogarnet and hydrotalcite were present as hydration products. Increasing the amount of gypsum increased the ratio of ettringite to monosulfate formed in the cement paste, lowered the amount of pore solution, delayed the dissolution of belite and ferrite, decreased the formation of strätlingite and, in the case of the ye’elimite-rich BCSA, led to an increase in compressive strength. Increased amounts of belite in the clinker led to the formation of higher quantities of C–S–H, at the expense of strätlingite and a lower compressive strength, as belite has a lower degree of reaction than ye’elimite and due to the formation of more C–S–H and strätlingite compared to the more space-filling ettringite. The thermodynamic model established for BCSA cement hydration agrees well with the experimental data. Compressive strength directly correlated with bound water from thermogravimetric analyses and inversely correlated with the porosity calculated from thermodynamic modelling.

scholarly journals The Influence and Application of Slag, Fly Ash, and Limestone Flour on Compressive Strength of Concrete Based on the Concrete Compressive Strength Development over Time (CCSDOT) Model

2020 ◽  
Vol 10 (10) ◽  
pp. 3572
Author(s):  
Jian Zheng ◽  
Guohua Liu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Mix Proportion ◽  
Practical Engineering ◽  
Compressive Strength Development ◽  
Compressive Strength Of Concrete ◽  
Selection Of

Concrete and cement have been widely used in past decades as a result of urbanization. More and more supplementary cementitious materials are adopted in concrete because its production complements environmental conservation. The influence of slag, fly ash, limestone, etc., on compressive strength of concrete is of interest to engineers worldwide. Many previous studies were specific to certain engineering or certain experiments that could not reveal the nature of the influence of the three supplementary cementitious materials on concrete’s compressive strength. The research concerning the influence of two or more kinds of supplementary cementitious materials on concrete’s compressive strength is still unclear. Moreover, there is a lack of clarity on the optimum proportion of one or more certain cementitious materials in practical engineering or experiments. To overcome these problems, this study adopts the concrete compressive strength development over time (CCSDOT) model, which generates an explicit formula to conduct quantitative research based on extensive data. The CCSDOT model performs well in fitting the compressive strength development of concrete containing cement, slag, fly ash, and limestone flour. The results reveal the nature of the influence of the three supplementary cementitious materials on concrete’s compressive strength through the parameter analysis in the model. Two application cases are analyzed concerning the selection of the three supplementary cementitious materials and design of concrete mix proportion for practical engineering. It is concluded that the CCSDOT model and the method in this study can possibly provide guidance on both the selection of supplementary cementitious materials and the design of optimal concrete mix proportion for practical engineering. Therefore, the study is highly essential and useful.

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