Effect Of Limestone Powder Research Articles

Effect of Limestone Powder on Microstructure and Strength of Ultra High Performance Cement-Based Materials

Effect of Limestone Powder on Microstructure and Strength of Ultra High Performance Cement-Based Materials

The Effect of Limestone Powder and Clay Content on MB Value of Manufactured Sand

In this paper, the correlation between limestone powder content and MB value in manufactured sand is analyzed and the effect of limestone powder content and clay content of manufactured sand on the MB value is studied, the results show that with the increase of pure limestone powder content, the MB values remained almost unchanged, and were less than 1.0; when the limestone powder content increased from 5% to 15%, with the increase of clay content, the MB value increased gradually; when the limestone powder content was taken as 7%, 12% and 15%, the clay content was taken as1.8%, 2.7% and 2.3% respectively with the MB value kept at 1.0, which still could meet the requirement of the engineering construction standard JGJ52-2006 about clay content.

The Effect of Limestone Powder and Clay Content on MB Value of Manufactured Sand

The Effect of Limestone Powder and Clay Content on MB Value of Manufactured Sand

C3A-CaSO4·2H2O 계의 수화반응에 미치는 석회석 미분말의 영향

In this work, effects of limestone powder on hydration of C 3 A-CaSO 4 ·2H 2 O system was discussed based on the XRD Quantitative analysis, and the possibility of Delayed Ettringite Formation was also discussed. The early hydration of C 3 A was delayed by addition of CaCO 3 powder. The delay effect was enhanced by increasing of CaCO 3 content and finer powder of CaCO 3 addition. After consumption of CaSO 4 ·2H 2 O, the reaction of CaCO 3 is started. Delayed Ettringite Formation would take place because monosulfoaluminate is not stable in presence of CaCO 3 . In order to prevent the delayed ettringite formation in C 3 A-CaSO 4 ·2H 2 O-CaCO 3 system, the reduction of monosulfoaluminate formation is important. Therefore, by increasing the amount of CaCO 3 addition and finer CaCO 3 powder addition, the delayed ettringite formation can be prevented.

Effect of Limestone Powder on Autogenous Shrinkage of Concrete

The effect law and mechanism of limestone powder on autogenous shrinkage of concrete was studied. The results indicate that limestone powder accelerates autogenous shrinkage speed of concrete on which effect of fineness is little, and limestone powder reduces autogenous shrinkage which decreases with the increase of fineness. The change law of autogenous shrinkage of concrete is consistent with that of chemically combined water of paste. Autogenous shrinkage of concrete is also divided into 2 stages according to the initial vapor saturated stage and subsequent reduction stage of interior relative humidity, with both showing a good linear correlation at each stage.

Influence of Limestone Powder on Immobilization of Chlorine Ion of Portland Cement

The effect of limestone powder on immobilization of chlorine ion of Portland cement was studied by the method of the chemical analysis. The immobilization of chlorine ion of Portland cement, which was hardened by cement clinker or cement clinker and gypsum mixed limestone powder with different proportions, was tested at 28d. The results show that the amount of immobilization of chlorine ion of Portland cement increases more than doubled, and the free chlorine ion content decreases 41% without gypsum, when the limestone powder content increases from 0% to 12%; the immobilization content of chlorine ion increases first, and then decreases, the free chlorine ion content decreases a little with gypsum, when the limestone powder content increases from 0% to 8% .

Study on the Ultra High Performance Concrete Containing Limestone Powder

A new kind of ultra high performance concrete containing limestone powder was studied in this paper. The results show that the compressive strength of the ultra high performance concrete containing limestone powder is higher than 120MPa; the hydration activity and the accelerating effect of limestone powder are obvious under the condition of high temperature. The limestone powder hydrated and formed calcium monocaboaluminate hydrates. The cost would be reduced when adding certain amount of limestone powder when confect ultra high performance concrete. It is economical and feasible.

Effect of limestone powder and fly ash on magnesium sulfate resistance of mortar

The effect of limestone powder and fly ash on magnesium sulfate resistance of mortar was studied by testing on the strength, expansion and hydration products of the specimens stored in MgSO4 solution at certain periods. The experimental results show that the strength of mortar stored in MgSO4 solution increases a little before 28 d, but decreases fast subsequently. The more the contents of limestone powder and fly ash, the less the strength losses. Mortar swells in the MgSO4 solution with the soaking time. And the more the contents of limestone powder and fly ash, the less the expansion rate is. The expansion or strength loss of mortars results from the expansion of gypsum, as well as the loss of Ca(OH)2 and other hydration products of cement. The magnesium sulfate resistance of the mortars containing limestone powder and fly ash is high.

Effect of limestone powder on microstructure of concrete

The effect of limestone powder on microstructure of concrete was studied by using mercury intrusion porosimetry (MIP), backscattering scanning electron(BSE), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The experimental results show that the compressive strength of concrete containing 100 kg/m3 limestone powder can meet the strength requirement. Limestone powder has not pozzolanic activity; it is still unhydrated at the age of 28 days. But its filling effect can make the paste matrix and the interfacial transition zone between matrix and aggregate denser, which will improve the performance of concrete.

The effect of limestone powder, fly ash and silica fume on the properties of self-compacting repair mortars

Self-compacting repair mortars (SCRM) are preferred for the rehabilitation and repair of reinforced concrete structures especially at narrow mould systems. Self compactability and stability are susceptible to ternary effects of chemical and mineral admixture type and their content. In this study, the effect of limestone powder (LP) on the properties of SCRM has been compared with other mineral additives (silica fume (SF) and fly ash (FA) and their combinations) effects. Fresh properties, flexural and compressive strengths and water absorption properties of mortars were determined. The use of SF in mortars significantly increased the dosage of superplasticiser (SP). At the same constant SP dosage (0·8%) and mineral additives content (30%), LP can better improve the workability than that of control and FA mixtures by 19% and 27%. However, the results of this study suggest that certain FA, SF and LP combinations can improve the workability of SCRMs, more than FA, SF and LP alone. LP can have a positive influence on the mechanical performance at early strength development while SF improved aggregate-matrix bond resulting from the formation of a less porous transition zone in mortar. SF can better reducing effect on total water absorption while FA and LP will not have the same effect, at 28 days.

Effects of Limestone Powder in Manufactured Fine Aggregate on Early Hydration Process and Types of Cement Hydrates

The crusher dust in Manufactured fine aggregate (MFA), e.g. limestone powder in calcareous MFA, constitutes micro gradation of the aggregate and suitable content of crusher dust in MFA can improve the properties of concretes. In this paper, early hydration processes of samples substituting limestone powder and fly ash for part of cement are analyzed, and effects of limestone powder on cement hydrates are studied through experiment of mortar prepared with MFA partially replaced by limestone powder and fly ash. The result reveals that both the dormant period and acceleration period of hydration ended earlier in the samples substituting limestone powder for part of cement, and amount of crystals of calcium hydroxide and hydrated calcium carboaluminate increases in hardened paste in the samples substituting limestone powder for part of MFA, i.e. calcareous dust (limestone powder) in MFA can stimulate and enhance hydration of cement.

Experimental Studies on the Volume Change of the Super High Strength and High Performance Concrete

Volume change of super high strength and high performance concrete with different binder-aggregate ratios and different curing conditions were investigated in this paper, and the volume changes of cement paste and mortar were also tested. The results indicated that the change of cement paste was much higher than mortar and concrete under the same curing conditions；the curing condition has a obvious influence on the volume change; there was a moisture swell for the water curing concrete; the specimens with limestone powder have smaller volume change than those specimens without limestone powder. The volume change mechanism was explained, and the effect of limestone powder on the volume change was also discussed.

XRD/Rietveld Analysis of the Hydration and Strength Development of Slag and Limestone Blended Cement

The X-ray diffraction (XRD)/Rietveld method was applied to analyze the hydration progress of cement paste prepared with blast furnace slag powder (BFS) and limestone powder (LSP). The Rietveld method can be used to quantify the amount of amorphous phase as well as crystalline phases. However, in cement paste containing BFS, two kinds of amorphous phases, unhydrated BFS and C-S-H, are included and the Rietveld method cannot distinguish them. In order to discriminate these two phases, a selective dissolution method was used to quantify the amount of unhydrated BFS. By combining these two methods, it became possible to quantify the amount of BFS and C-S-H in hydrated cement. The analysis results show that BFS accelerates the hydration of C3S, C3A, and especially C4AF. The strength increasing effect of LSP is more pronounced in the ordinary Portland cement (OPC) - BFS system than in the OPC system. This is attributed to the higher amount of calcium aluminate hydrates generated in the BFS contained system compared to the system without BFS. The additional calcium aluminate hydrates fill pores as calcium carboxaluminate by the reaction with LSP, increasing the compressive strength. These results show the effectiveness of the XRD/Rietveld method as an analysis tool for cement hydration relating to various properties of cement materials.