scholarly journals The influence of sulfate availability on rheology of fresh cement paste

2020 ◽  
Vol 30 (1) ◽  
pp. 54-63
Author(s):  
Willy Mbasha ◽  
Rainer Haldenwang ◽  
Irina Masalova
Keyword(s):  
Yield Stress ◽  
Calcium Sulfate ◽  
Chemical Properties ◽  
Plastic Viscosity ◽  
Cement Clinker ◽  
Flow Properties ◽  
Cement Pastes ◽  
Hardened Properties ◽  
Physical And Chemical ◽  
And Chemical Properties

AbstractNatural gypsum can degenerate into hemihydrate during cement clinker grinding which changes the physical and chemical properties of cement hydration, affecting therefore the fresh and hardened properties of cement based materials. Cement systems containing a constant total amount of calcium sulfate (4%) with relative proportions of hemihydrate and natural gypsum were considered. Rheological measurements were executed on an Anton Paar MCR51 rheometer to evaluate the flow properties of cement pastes. Results show that, the yield stress and the plastic viscosity of cement pastes were affected when the degeneration of natural gypsum exceeded 50%. Above this concentration, the yield stress remarkably increased and a variation in plastic viscosity of about 50% was observed. Using TG-DSC techniques, it was shown that, the amount of formed ettringite could not explain these rheological changes. However, centrifugational packing and SEM-SE measurements confirmed that, more than the amount of ettringite precipitated, ettringite morphology plays a major role in controlling the yield stress and plastic viscosity of fresh cement pastes.

Application of a-SiO2 Rich Additives in Cement Paste

2015 ◽  
Vol 749 ◽  
pp. 362-367 ◽  
Author(s):  
Jaroslav Pokorný ◽  
Milena Pavlíková ◽  
Eva Navrátilová ◽  
Pavla Rovnaníková ◽  
Zbyšek Pavlík ◽  
...  
Keyword(s):  
Cement Paste ◽  
Bending Strength ◽  
Setting Time ◽  
Chemical Properties ◽  
Xrd Analysis ◽  
Fast Reaction ◽  
Cement Pastes ◽  
Matrix Density ◽  
Physical And Chemical ◽  
And Chemical Properties

The effect of a-SiO2 of various origin on the properties of cement paste with incorporated different silica containing materials is experimentally studied in the paper. For the applied a-SiO2 materials, basic physical and chemical properties are accessed, together with their chemical composition. Amount of amorphous phase of SiO2 in particular siliceous materials is determined using XRD analysis. Matrix density, bulk density, total open porosity, compressive and bending strength are measured for all developed pastes with incorporated a-SiO2 containing materials, together with initial and final setting time of fresh mixtures. The obtained data give evidence on a high and fast reaction activity of tested siliceous materials which results in a significant improvement of porosity and mechanical strength of a-SiO2 modified cement pastes.

Concrete Dust Influence on Cement Stone Properties

1970 ◽  
Vol 17 (2) ◽  
pp. 197-202
Author(s):  
Donatas GRIGONIS ◽  
Ernestas IVANAUSKAS ◽  
Žymantas RUDŽIONIS
Keyword(s):  
Chemical Properties ◽  
Cement Stone ◽  
Exothermic Effect ◽  
Physical And Chemical Properties ◽  
Qualitative Properties ◽  
Cement Replacement ◽  
Hardened Properties ◽  
Physical And Chemical ◽  
Standard Tests ◽  
And Chemical Properties

The results of experimental investigation of reusing concrete dust (CD), from old concrete construction demolition as cement replacement are presented in the article. Tests were conducted on cement mass by replacing 0 % - 30 % of cement with CD mass. The physical and chemical properties of CD were stock reviewed to assess the possible influence on both fresh and hardened properties of cement. The results of qualitative properties evaluated by standard tests on different mixtures of Portland cement and CD proved to be promising. The comprehensive series of tests included rheology, compressive strength, absorbability, density, exothermic effect and rentgenographic. According to our findings CD can be used as cement replacement without strongly influencing the cement stone properties; CD can also become an alternative to  ecological concrete.http://dx.doi.org/10.5755/j01.ms.17.2.492

scholarly journals Hydrophobic Cryogels Based on Polyvinyl Alcohol and Polymeric Oil Resins

2019 ◽  
pp. 166-176
Author(s):  
Maria S. Fufaeva ◽  
Darya V. Fisenko ◽  
Vladimir N. Manzhay ◽  
Vladimir G. Bondaletov ◽  
Lyubov K. Altunina
Keyword(s):  
Polyvinyl Alcohol ◽  
Chemical Properties ◽  
Flow Properties ◽  
Road Pavement ◽  
Binder Component ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Pavement Construction ◽  
Physical And Chemical ◽  
And Chemical Properties

The paper presents the results of studies of the flow properties of viscous compositions consisting of polyvinyl alcohol, polymeric oil resin, and water. After a freeze-thaw cycle three-component cryogels are formed from them. Mechanical, thermal, physical, and chemical properties of the resulted elastic samples are studied. The prospects of using hydrophobic cryogels filled with polymeric oil resin as a binder component for road pavement construction are presented

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

Tailoring microstructures of materials through biomimetics

1993 ◽  
Vol 51 ◽  
pp. 500-501
Author(s):  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Chemical Properties ◽  
Design And Synthesis ◽  
Structure Sensitive ◽  
Macro Scale ◽  
Methods Of Synthesis ◽  
Successive Level ◽  
Engineering Materials ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Synthesis Of Materials

Biomimetics involves investigation of structure, function, and methods of synthesis of biological composite materials. The goal is to apply this information to the design and synthesis of materials for engineering applications.Properties of engineering materials are structure sensitive through the whole spectrum of dimensions from nanometer to macro scale. The goal in designing and processing of technological materials, therefore, is to control microstructural evolution at each of these dimensions so as to achieve predictable physical and chemical properties. Control at each successive level of dimension, however, is a major challenge as is the retention of integrity between successive levels. Engineering materials are rarely fabricated to achieve more than a few of the desired properties and the synthesis techniques usually involve high temperature or low pressure conditions that are energy inefficient and environmentally damaging.In contrast to human-made materials, organisms synthesize composites whose intricate structures are more controlled at each scale and hierarchical order.

Response of corn (Zea mays L.) to various organic-based fertilizers in marginal upland of Sta. Rita, Samar

2017 ◽  
pp. 31-43
Author(s):  
Berta Ratilla ◽  
Loreme Cagande ◽  
Othello Capuno
Keyword(s):  
Block Design ◽  
Management Strategies ◽  
Chemical Properties ◽  
Organic Fertilizers ◽  
Growth And Yield ◽  
Physical And Chemical Properties ◽  
Total N ◽  
Randomized Complete Block Design ◽  
Physical And Chemical ◽  
And Chemical Properties

Organic farming is one of the management strategies that improve productivity of marginal uplands. The study aimed to: (1) evaluate effects of various organic-based fertilizers on the growth and yield of corn; (2) determine the appropriate combination for optimum yield; and (3) assess changes on the soil physical and chemical properties. Experiment was laid out in Randomized Complete Block Design, with 3 replications and 7 treatments, namely; T0=(0-0-0); T1=1t ha-1 Evans + 45-30-30kg N, P2O5, K2O ha-1; T2=t ha-1 Wellgrow + 45-30-30kg N, P2O5, K2O ha-1; T3=15t ha-1 chicken dung; T4=10t ha-1 chicken dung + 45-30-30kg N, P2O5, K2O ha-1; T5=15t ha-1 Vermicast; and T6=10t ha-1 Vermicast + 45-30-30kg N, P2O5, K2O ha-1. Application of organic-based fertilizers with or without inorganic fertilizers promoted growth of corn than the control. But due to high infestation of corn silk beetle(Monolepta bifasciata Horns), its grain yield was greatly affected. In the second cropping, except for Evans, any of these fertilizers applied alone or combined with 45-30-30kg N, P2O5, K2O ha-1 appeared appropriate in increasing corn earyield. Soil physical and chemical properties changed with addition of organic fertilizers. While bulk density decreased irrespective of treatments, pH, total N, available P and exchangeable K generally increased more with chicken dung application.

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