Inhibiting Effect of Mineral Powder on Sulfate Attack of Cement Mortar

2006 ◽  
Vol 302-303 ◽  
pp. 73-78 ◽  
Author(s):  
Quan Lin Niu ◽  
Nai Qian Feng
Keyword(s):  
Cement Mortar ◽  
Diffusion Mechanism ◽  
Resistance Coefficient ◽  
Sulfate Attack ◽  
Mineral Admixtures ◽  
Capillary Absorption ◽  
Inconsistent Result ◽  
Inhibiting Effect ◽  
Chemical Attack ◽  
Physical And Chemical

ASTM C1012 and GB2420 method were employed to evaluate the inhibiting effect of different mineral admixtures on sulfate attack of cement mortar, and the mass loss of mortar specimens after drying-wetting cycles was measured for comparison. It is shown that all the mineral admixtures, including ground blast furnace slag (SL), fly ash (FA), natural zeolite (NZ) and metakaolin (MK) were effective in decreasing the 15-week expansion and increasing the corrosion resistance coefficient of the specimens immersed in Na2SO4 solution. The wetting and drying test however, showed inconsistent result, as both physical and chemical attack may soon occur due to quick accumulation of sulfate by capillary absorption instead of diffusion mechanism.

Study on the Durability of Concrete with Mineral Admixtures to Sulfate Attack by Wet-Dry Cycle Method

2011 ◽  
Vol 295-297 ◽  
pp. 165-169
Author(s):  
Guan Guo Liu ◽  
Jing Ming ◽  
Xiong Wen Zhang ◽  
Ai Bin Ma
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sulfate Attack ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Partial Replacement ◽  
Change Environment ◽  
Physical Mechanisms ◽  
Chemical Attack ◽  
Tidal Area

Sulfate attack is one of several chemical and physical mechanisms of concrete deterioration. In actual situation, concrete structures always suffer from the coupled effects of multifactor such as wet-dry cycle and sulfate attack when exposed to tidal area or groundwater level change environment. Partial replacement of cement with mineral admixture is one of the efficient methods for improving concrete resistance against sulfate attack. In this regard, the resistance of concrete with fly ash and slag to sulfate attack was investigated by wet-dry cycle method. The degree of sulfate attack on specimens after different cycles was observed using scanning electron microscopy. The results of compressive strength and percentage of compressive strength evolution factor at various cycling times show an increase in the sulfate resistance of concrete with 60% of fly ash and slag than that only with 40% fly ash. The microstructural study indicates that the primary cause of deterioration of concrete under wet-dry cycle condition is swelling of the sulfate crystal rather chemical attack.

Effect of Different Mineral Admixtures on Sulfate Attack to Mortars

2009 ◽  
Vol 405-406 ◽  
pp. 278-282 ◽  
Author(s):  
Quan Lin Niu ◽  
Nai Qian Feng
Keyword(s):  
Corrosion Resistance ◽  
Blast Furnace Slag ◽  
Natural Zeolite ◽  
Resistance Coefficient ◽  
Expansion Ratio ◽  
Sulfate Attack ◽  
Mineral Admixtures ◽  
Granulated Blast Furnace Slag ◽  
Mortar Bar ◽  
Furnace Slag

Corrosion resistance coefficient of mortars incorporating different mineral admixtures were tested according to GB2420, and the expansion ratio of mortar bar immersed in 5% Na2SO4 solution was measured according to ASTM C1012. It is shown that all the mineral admixtures, including ground granulated blast furnace slag (SL) fly ash (FA), natural zeolite (NZ) and metakaolin (MK) were effective in decreasing the 15-week expansion and increasing the corrosion resistance coefficient of the specimens immersed in Na2SO4 solution as well.

scholarly journals Reología, comportamiento físico-mecánicos y de durabilidad de hormigones con nanosílice.

2012 ◽  
Vol 2 (2) ◽  
pp. 82-88
Author(s):  
E. Téllez Girón ◽  
A .N. Martín Acosta ◽  
A. Pérez Hernández ◽  
U. Verdecia Rodríguez
Keyword(s):  
Resistance Coefficient ◽  
Ultrasonic Pulse ◽  
Effective Porosity ◽  
Capillary Absorption ◽  
Water Absorption Coefficient ◽  
Characterization Methods ◽  
Natural Pozzolans ◽  
Chemical Admixtures ◽  
Microscopy Analysis

RESUMENLa nanosílice es una de las aplicaciones de la nanotecnologia en la construcción, a base de sílica amorfa nanométrica, que se emplea igual que la microsílice, pero con la ventaja que no produce contaminación al medio ambiente y la agresión a la salud por inhalación de ésta. Se dan los resultados de la caracterización física de dos compuestos de nanosílice comerciales mediante los métodos de la caracterización de aditivos y el empleo de la microscopia para la determinación de compuestos fundamentales, de sus actividades puzolánicas en morteros, así como la determinación de la absorción capilar, velocidad ultrasónica, masa volumétrica, coeficientes de resistencia a la penetración de agua, coeficiente de absorción de agua y porosidad efectiva en hormigones elaborados con los compuestos evaluados y en hormigones con aditivos superplastificantes y tobas zeolitizadas como patrones de comparación. Los valores demuestran un mejor comportamiento de durabilidad en los hormigones elaborados con nanosílice.Palabras Clave: nanotecnología; nanosílice; microsílice; aditivos químicos; adiciones.ABSTRACTNanosilice based in nanometric amorphous silica is one of the aplications of nanotechnology in the building industry, that has the same use than microsilica, but with the advantage that it does not produce environmental pollution or respiratory complains due to inhalation. We give the results of the physical characterization of two commercial nanosilice compounds by the admixtures characterization methods and electronic microscopy analysis to determine the fundamental compound, its pozzolanic activity in mortars, as well as its capillary absorption, ultrasonic pulse speed, volumetric mass, water penetration resistance coefficient, water absorption coefficient and effective porosity in concrete with nanosilice and in ordinary concrete with natural pozzolans and superplasticizer admixtures like comparative patterns. Results show a better behavior of durability in concretes with nanosilice.Keywords: nanotechnology; nanosilica; microsilica; chemical admixtures; additions.

Study on Sulfate Resistance of Concrete with Compound Mineral Admixture

2011 ◽  
Vol 99-100 ◽  
pp. 420-425 ◽  
Author(s):  
Qian Rong Yang ◽  
Xiao Qian Wang ◽  
Hui Ji
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Steel Slag ◽  
Sulfate Attack ◽  
Mineral Admixture ◽  
Sulfate Resistance ◽  
Chemical Attack ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

The strength, expansion and amount of scaling of concrete with compound mineral admixture (CMA) from steel slag, granulated blast furnace slag and fly ash were studied. The result shows that damage by crystallization press from sulfate attack when concrete was exposed to sulfate environments under wetting–drying alternation is much larger than that from sulfate chemical attack. Adding CMA to concrete could reduce the damage from expansion of concrete caused by sulfate chemical attack, but the resistance of concrete to damage by crystallization press from sulfate attack was remarkably reduced.

scholarly journals Effect of Durability properties on Geopolymer concrete – A Review

2020 ◽  
Vol 184 ◽  
pp. 01092
Author(s):  
M Niveditha ◽  
Srikanth Koniki
Keyword(s):  
Environmental Sustainability ◽  
Elevated Temperatures ◽  
Mineral Admixtures ◽  
Geopolymer Concrete ◽  
Conventional Concrete ◽  
Curing Conditions ◽  
Durability Properties ◽  
Chemical Attack ◽  
Strength And Durability ◽  
Micro Structures

Geopolymer concrete is prepared by reacting silicate as well as aluminate consisting materials with a caustic activator. More often, waste materials such as GGBS, fly ash, slag from metal and iron production are used. Recent investigations adding new materials like Alccofine, which improves the properties of geopolymer concrete even at ambient temperature condition. This research paper presents a details literature survey on the durability properties of geopolymer concrete. Various research literatures are previewed on durability of geopolymer concrete with the addition of different supplementary cementious materials as their necessity is increasing due to insistent constituents. Past studies from the literature reviews suggested that replacement of cement with chemical and mineral admixtures enhanced the properties of strength and durability of concrete. The micro structures, Morphological structures by SEM, lower shrinkage, higher mechanical strengths, superior durability with environmental sustainability are observed. XRD studies shown enhanced polymerisation reaction which is responsible for development of strength. Elevated temperatures and Surface deterioration are controlled in GPC than OPC. Geopolymer concrete provides better resistance for specimens to chemical attack and also water absorption, sorptivity, porosity have good influence to the durability properties in ambient curing conditions compared to conventional concrete.

scholarly journals Mechanical Properties and Microscopic Mechanism of Coral Sand-Cement Mortar

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Luoxin Wang ◽  
Junshuai Mei ◽  
Jing Wu ◽  
Xingyang He ◽  
Hainan Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cement Mortar ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hardened Cement ◽  
Hydration Reaction ◽  
Microscopic Mechanism ◽  
X Ray ◽  
Volume Stability ◽  
Coral Sand

The workability and mechanical performance of coral sand-cement mortar (coral mortar, for short) and the modification effects of mineral admixtures on the coral mortar were studied in this paper. The results showed that the strength of coral mortar was lower than that of standard mortar, but the strength of coral mortar was improved by compositing with the mineral admixture, which can be attributed to the improvement of the microstructure and interface transition area. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to explore the microscopic mechanism involved in the mechanical properties, volume stability, and hydration of mortar. The analyses revealed that the internal curing effect of coral sand improved the mechanical properties of mortar and its ability to resist shrinkage. The uneven surface of coral sand formed a meshing state of close combination with the hardened cement mortar, which helped to improve the volume stability of mortar. The Ca2+ and Mg2+ ions from coral sand participated in the hydration reaction of cement, which contributed to generating more hydration products. Moreover, the microaggregate filling and pozzolanic effects of fly ash and slag improved the mechanical properties of coral mortar and resistance to chloride ion diffusion.

Use of mineral admixtures to prevent thaumasite formation in limestone cement mortar

2003 ◽  
Vol 25 (8) ◽  
pp. 969-976 ◽  
Author(s):  
S. Tsivilis ◽  
G. Kakali ◽  
A. Skaropoulou ◽  
J.H. Sharp ◽  
R.N. Swamy
Keyword(s):  
Cement Mortar ◽  
Mineral Admixtures ◽  
Limestone Cement
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