scholarly journals Effect of the water/binder ratio on the hydration process of Portland cement pastes with silica fume and metakaolin

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Mara Monaliza Linhares Pereira ◽  
Ana Luiza Rocha de Souza ◽  
Valdirene Maria Silva Capuzzo ◽  
Rodrigo de Melo Lameiras
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Cementitious Materials ◽  
Hydration Process ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Binder Ratio ◽  
Water Binder Ratio ◽  
Mineralogical Phases

abstract: The microstructure of cement pastes is important to understand the effect of some parameters in the hydration process. In this context, this study had as objective to evaluate the effect of different water/binder (w/b) ratios in the hydration process of cementitious pastes produced with and without incorporation of silica fume and metakaolin. The pastes were obtained with water/binder ratios of 0.3, 0.4 e 0.5, with replacement, by weight, of Portland cement for silica fume and metakaolin, in the contents of 10% and 20%, respectively. It was performed the X-ray diffraction test of the pastes in the ages of 1, 3, 7, and 28 days, to evaluate the hydration evolution of the cementitious materials. According to the results obtained, it was observed that the cementitious pastes presented similar mineralogical phases, except for the pastes containing metakaolin due to the formation of new aluminate phases. With the increase of the water/binder ratio, the pozzolanic reactions and hydration occurred in greater proportion, standing out the metakaolin with greater reactivity.

Effect of Heat Treatment on Properties of Portland Cement Pastes: Determination through Ultra-Microhardness Test

2015 ◽  
Vol 820 ◽  
pp. 492-496
Author(s):  
D.C.S. Garcia ◽  
Roberto Braga Figueiredo ◽  
Maria Teresa Paulino Aguilar
Keyword(s):  
Heat Treatment ◽  
Portland Cement ◽  
Optical Microscopy ◽  
Silica Fume ◽  
Ordinary Portland Cement ◽  
Cement Pastes ◽  
Microhardness Test ◽  
Material Hardness ◽  
Binder Ratio ◽  
Water Binder Ratio

The aim of this paper was to investigate the influence of heat treatment on hardness evolution of cement pastes containing silica fume. The specimens were prepared with Ordinary Portland Cement, water/binder ratio of 0,40 and 25% wt. silica fume. The specimens were cast at room temperatures and after 24 hours, they were placed in a furnace for 24 hours, with heat regimes of 100°C, 200°C and 300°C and then submitted to the ultra-microhardness test. The microstructure was analyzed using optical microscopy. The results showed that the silica fume prevents the production of calcium hydroxide and the heat treatment increases the material hardness.

Pozzolanic Reactions in Cementitious Materials for Subsurface Applications

2014 ◽  
Author(s):  
Neven Ukrainczyk ◽  
Jure Zlopaša ◽  
Eduardus Koenders ◽  
Camila Aparecida Abelha Rocha ◽  
Romildo Dias Toledo Filho
Keyword(s):  
Silica Fume ◽  
Isothermal Calorimetry ◽  
Cementitious Materials ◽  
Microstructural Development ◽  
Oil Well ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
Beneficial Effects ◽  
Binder Ratio ◽  
Offshore Industry

Silica fume (SF) is used as a constituent to formulate cementitious materials for subsurface (oil-well) applications, e.g. by the offshore industry. Using green supplementary pozzolanic materials like silica fume could both improve the material’s performance and the footprint of the sustainable solution. X-ray diffraction and isothermal calorimetry were employed to investigate the evolution of cement paste hydration (water to binder ratio 0.44) after 14 h, 3, 7, and 28 days of curing. Experimental results are presented for both cement pastes made of Class G Portland cement and for a blended paste system where 8% of the Class G cement has been replaced by silica fume. The results indicate beneficial effects of SF on the microstructural development of the slurry.

scholarly journals Synthesis of a New Polycarboxylate at Room Temperature and Its Influence on the Properties of Cement Pastes with Different Supplementary Cementitious Materials

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shuncheng Xiang ◽  
Yingli Gao ◽  
Caijun Shi
Keyword(s):  
Room Temperature ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Heat Evolution ◽  
Hydration Heat ◽  
Supplementary Cementitious Materials ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Water Binder Ratio

Three polycarboxylates with different comb structures (i.e., the same degree of polymerization in side chains but different main chains) were synthesized via radical polymerization reaction at room temperature. The effect of polycarboxylates on the surface tension and the flowability in cement pastes was determined. The best product was selected to study its effects on the hydration heat evolution, compressive strength, autogenous shrinkage, and drying shrinkage of cement pastes with different kinds and contents of supplementary cementitious materials. The results showed that with the increase of molar ratio between AA and TPEG to 6 : 1, we could synthesis the best product. When the water-binder ratio was 0.4, with the increase of polycarboxylates, the cement hydration heat evolution had been slowed down, and the more the dosage was, the more obvious the effect was. Adding supplementary cementitious materials to cement under the same experimental conditions also played a mitigation role in slowing down the hydration heat. When the water-binder ratio was 0.3, supplementary cementitious materials could increase the strength of cement by 24.5% in maximum; its autogenous shrinkage and drying shrinkage could be decreased, respectively, by 60.1% and 21.9% in the lowest.

Mineralogical Analysis of Portland Cement Pastes Rehydrated

2020 ◽  
Vol 46 (1) ◽  
pp. 15-23
Author(s):  
Tiago Assunção Santos ◽  
Guilherme Augusto de Oliveira e Silva ◽  
Daniel Véras Ribeiro
Keyword(s):  
Portland Cement ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Curing Period ◽  
Hydraulic Binder ◽  
Before And After ◽  
Hydrated Products ◽  
Rehydration Process

Hydrated products, such as (hydrated) cement pastes, decomposition through physical-chemical alterations when submitted to high temperatures. One of the main factors that lead to microstructural changes during calcination up to 800ºC, is the dehydration phases of hydrated Portland cement. The present study sought to characterize crystalline phases occurring before and after calcination to the produced pastes using X-ray diffraction (XRD) analysis. Cement pastes were produced using Portland cement CP V-ARI RS, similar to type II (ASTM C150-07), with water/cement ratio 0.5. After a 28-day curing period, the pastes were calcinated at 800°C for 60 minutes with a 10°C/min heating rate. Afterwards, the newly produced hydraulic binder was cooled abruptly and reactivated through a rehydration process, and underwent analyses on the 7 and 28 day. During this study it was observed that the originally hydrated products can be rehydrated.

Preliminary Study of the Use of a Secondary Lead Smelting Slag as an Addition to Portland Cement

2018 ◽  
Vol 761 ◽  
pp. 175-180 ◽  
Author(s):  
Janneth Torres Agredo ◽  
Sergio Gallego Restrepo ◽  
Fernando Álvarez Hincapié ◽  
Daniela Giraldo Alzate
Keyword(s):  
Portland Cement ◽  
Pozzolanic Activity ◽  
Hydration Process ◽  
Partial Replacement ◽  
Curing Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lead Smelting ◽  
Smelting Slag ◽  
Preliminary Study

In this work, the preliminary study about the use of secondary lead smelting slag (SLSS) as an addition to Portland cement is presented. SLSS is a waste from a Colombian secondary lead smelter. The chemical, physical and mineralogical characteristics of the raw materials were evaluated by X-ray fluorescence, particle size and X-ray diffraction. To assess the SLSS pozzolanic activity, the ASTM C618 standards were used. Additionally, cement pastes added with SLSS as Portland cement replacement in proportions of 0, 5, 10, 20 and 30% were prepared, to study the hydration process at 7, 14 and 28 of curing times. To determine the hydration products the technique of X-ray diffraction was used. Furthermore, the environmental test TCLP (Toxicity Characteristic Leaching Procedure) was performed in pastes with 28 days of curing time. Results showed that SLSS reported an index of pozzolanic activity of 87%, this value meets the standard (greater than 75%). The hydration process showed that since early curing time the waste presented a good reactivity. TCLP results satisfied the environmental standards. The outcomes showed that this waste could be used as a partial replacement of Portland cement.

scholarly journals Measurement of Pozzolanic Activity Index of Scoria, Pumice, and Rice Husk Ash as Potential Supplementary Cementitious Materials for Portland Cement

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Hieronimi A. Mboya ◽  
Cecil K. King’ondu ◽  
Karoli N. Njau ◽  
Alex L. Mrema
Keyword(s):  
Portland Cement ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Activity Index ◽  
Cementitious Materials ◽  
Pozzolanic Activity ◽  
Supplementary Cementitious Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Setting Times

This work investigated the properties of scoria and pumice as supplementary cementitious materials (SCMs) for Portland cement and compared to those of rice husk ash (RHA). X-ray fluorescence, X-ray diffraction, and pozzolanic activity index (PAI) tests confirmed the suitability of these two materials as potential SCMs. Scoria and RHA samples achieved over 75% PAI at 7 days whereas pumice did this after 28 days. Initial and final mean setting times observed for the composite cement blended with these materials were 166 and 285 min, respectively. These setting times are longer than that of ordinary Portland cement but shorter compared to that of common Portland pozzolana cement. The ultimate mean compressive strengths achieved at 28 days of curing were 42.5, 44.8, and 43.0 MPa for scoria, pumice, and RHA, respectively, signifying that these materials are good SCMs. Higher fineness yielded higher ultimate mean strength. For instance, a scoria sample with a fineness of 575 m2/kg achieved the strength of 52.2 MPa after 28 days.

Characterization of Cement-Rice Husk Ash Composites

2017 ◽  
Vol 866 ◽  
pp. 187-190
Author(s):  
Thossapon Jaihlong ◽  
Nittaya Jaitanong ◽  
Suparut Narksitipan
Keyword(s):  
Portland Cement ◽  
Rice Husk ◽  
Fiber Optic ◽  
Rice Husk Ash ◽  
Cementitious Materials ◽  
Cement Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lime Water

In present research, the cement-rice husk ash composites were prepared and characterized. The samples were added fiber optic and rice husk ash was used as replacement cementitious materials at 10, 20, 30 and 40 wt% of portland cement. The samples were demolded after 24 h casting and cured in saturated lime water for 3 days. After these periods, the samples were wrapped with plastics films for 7 and 28 days. Then, samples were dried in air for 24 h. The chemical compositin of portland cement and rice husk ash were characterized by using x-ray fluorence spectrometry (XRF). Additionally, dried samples were analysized phase compositions and crystalline structure by using x-ray diffraction (XRD) technique. The chemical element compositions and microstructure were detected by scanning electron microscopy (SEM), respectively. Moreover, The effect of rice husk ash in these cement composites were investigated in this research.

scholarly journals Phase Composition of Silica Fume—Portland Cement Systems Formed under Hydrothermal Curing Evaluated by FTIR, XRD, and TGA

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2786
Author(s):  
Eva Kuzielová ◽  
Michal Slaný ◽  
Matúš Žemlička ◽  
Jiří Másilko ◽  
Martin Tchingnabé Palou
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
High Temperature Phase ◽  
Molecular Water ◽  
Temperature Phase ◽  
Polymerization Degree ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Treatment Regimes

Two substitution levels of Portland cement by silica fume (SF; 30 and 50 mass%) and three hydrothermal treatment regimes (0.5, 1.2, and 2 MPa and 165, 195, and 220 °C for 7 days, respectively) were selected for the investigation of high-temperature phase formation. A combination of thermogravimetric, X-ray diffraction, and Fourier transform infrared analyses in the mid-IR region was used to overcome the shortcomings of individual techniques for the identification of these complex systems. Changes in molecular water amounts, the polymerization degree of silicate chains, or their decomposition due to transformations and crystallization of phases at hydrothermal conditions were observed and discussed concerning composition. Contrary to the calciochondrite, hydrogrossular phases, α-C2SH, and jaffeite detected in the systems without SF, a decrease in CaO/SiO2 ratio resulted in the formation of stable tobermorite in the case of 30 mass% SF, whilst calcium hydrogen silicate, gyrolite, and cowlesite were identified as more thermally stable phases in the samples with 50 mass% SF.

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