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

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.

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Effect of mineral admixtures on the mixed-mode (I/II) fracture characterization of cement mortar: CTS, CSTBD and SCB specimens

Engineering Fracture Mechanics ◽

10.1016/j.engfracmech.2014.12.008 ◽

2015 ◽

Vol 134 ◽

pp. 20-34 ◽

Cited By ~ 16

Author(s):

Hadi Fathipour Azar ◽

Naghdali Choupani ◽

Hassan Afshin ◽

Rasoul Hamidzadeh Moghadam

Keyword(s):

Mixed Mode ◽

Cement Mortar ◽

Mineral Admixtures ◽

Mode I ◽

Fracture Characterization

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Effect of steel slag powder, fly ash, and silica fume on the mechanical properties and durability of cement mortar

Materials Express ◽

10.1166/mex.2019.1587 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1049-1054

Author(s):

Yunxia Lun ◽

Fangfang Zheng

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Fly Ash ◽

Silica Fume ◽

Cement Mortar ◽

Steel Slag ◽

Mineral Admixtures ◽

Partial Replacement ◽

Slag Powder ◽

Steel Slag Powder

This study is aimed at exploring the effect of steel slag powder (SSP), fly ash (FA), and silica fume (SF) on the mechanical properties and durability of cement mortar. SSP, SF, and FA were used as partial replacement of the Ordinary Portland cement (OPC). It was showed that the compressive and bending strength of steel slag powder were slightly lower than that of OPC. An increase in the SSP content caused a decrease in strength. However, the growth rate of compressive strength of SSP2 (20% replacement by the weight of OPC) at the curing ages of 90 days was about 8% higher than that of OPC, and the durability of SSP2 was better than that of OPC. The combination of mineral admixtures improved the later strength, water impermeability, and sulfate resistance compared with OPC and SSP2. The compressive strength of SSPFA (SSP and SF) at 90 days reached 70.3 MPa. The results of X-ray diffraction patterns and scanning electron microscopy indicated that SSP played a synergistic role with FA or SF to improve the performance of cement mortar.

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The Influence of Combined Admixture of Super-Fine Limestone Powder and Low-Quality Fly Ash on the Performance of Cement Mortar

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.652-654.1181 ◽

2013 ◽

Vol 652-654 ◽

pp. 1181-1184

Author(s):

Guo Qiang Xu ◽

Zhi Guo You ◽

Lin Gao ◽

Dian Li Han

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Flexural Strength ◽

Cement Mortar ◽

Limestone Powder ◽

Mineral Admixtures ◽

Test Results ◽

Maximum Compressive Strength

The influence of admixture of super-fine limestone powder and low-quality fly ash in different proportions on the fluidity and strength of cement mortar is studied. The test results show that the mortar fluidity increases with the increase of the super-fine limestone powder (the mixing amount of fly ash reduces), and the strength of cement mortar can improve when limestone powder and low-quality fly ash are combined admixed to a certain ratio. The maximum flexural strength of the 28d mortar is 9.8MPa and its maximum compressive strength is 42.2MPa, and at this time, the limestone powder accounts for 33.3% of the mineral admixtures. However, when the mixing amount of super-fine limestone powder is over a certain range, the strength of 28d cement mortar will reduce.

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Research on Polypropylene Fiber and Mineral Admixtures on Fluidity of Cement-Based Materials

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.328-330.1301 ◽

2011 ◽

Vol 328-330 ◽

pp. 1301-1304

Author(s):

Xue Fei Li ◽

Tao Guo

Keyword(s):

Fly Ash ◽

Cement Mortar ◽

Polypropylene Fiber ◽

Maximum Flow ◽

Mineral Admixture ◽

Mineral Admixtures ◽

Polypropylene Fibers ◽

Intensity Level ◽

Reticular Fibers ◽

Cement Based Materials

The purpose of this paper is based on the cement-based materials by adding fibers and mineral admixtures for composite, to cement the improvement of liquidity. Experiment with the intensity level of 42.5 ordinary portland cement, by adding polypropylene fibers, slag and fly ash cement mortar as a mineral admixture, the production of cement mortar matrix for the test, were conducted on a variety of mix Fluidity test. Experiments show that the addition of polypropylene fiber is not conducive to the mobility of mortar, especially monofilament fiber was more obvious than the reticular fibers. To join the slag, fly ash, mortar fluidity increased, indicating that slag and fly ash added to improve the workability of cement-based materials. When the fiber content reaches the maximum degree of maximum flow, indicating that slag, fly ash and polypropylene fibers will increase the combined effect of fluidity value. This innovation is obtained by adding fiber cement-based materials for toughening effect, with the use of mineral admixture can improve the overall performance of cement based materials, with further research and promotion value.

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Long Term Behaviour of Portland Limestone Cement Concrete Exposed to Combined Chloride and Sulfate Environment. The Effect of Limestone Content and Mineral Admixtures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.688.185 ◽

2013 ◽

Vol 688 ◽

pp. 185-192

Author(s):

Konstantinos Sotiriadis ◽

Sotirios Tsivilis ◽

Jana Kosíková ◽

Vít Petranek

Keyword(s):

Fly Ash ◽

Visual Assessment ◽

Xrd Analysis ◽

Mineral Admixtures ◽

Cement Concrete ◽

Analytical Technique ◽

Blastfurnace Slag ◽

Concrete Damage ◽

Limestone Cement

The long term behaviour of limestone cement concrete, stored in combined chloride and sulfate environment, was studied, taking into consideration the effect of both the limestone content of the cement used and the mineral admixtures addition. Concrete specimens of seven different compositions were prepared. Three of them were made from ordinary Portland cement and from two Portland limestone cements (limestone content: 15% and 35% w/w). The rest four compositions were prepared by substituting a certain amount of the limestone cement (15% w/w limestone content) with natural pozzolana, fly ash, blastfurnace slag or metakaolin. The specimens were immersed in four solutions of various sulfate and chloride contents and stored at 5oC. Visual assessment of the specimens and mass measurements took place up to 55 months. XRD analytical technique was used to identify thaumasite in the deteriorated parts of the specimens. Higher contents of limestone in cement and of sulfates in the storage solutions resulted in more intensive concrete damage. The use of mineral admixtures improved the behaviour of limestone cement concrete. After 24 months of exposure, chlorides delay the deterioration of limestone cement concretes caused by sulfates. After 55 months, the presence of chlorides led to a greater mass loss for them. The specimens containing mineral admixtures showed more intensive deterioration at 24 months when chlorides were present along with sulfates. Their mass seems to not be affected by chlorides. Fly ash was proved as the most efficient material to improve limestone cement concrete's performance, while concrete containing metakaolin suffered from significant damage after 55 months. XRD analysis showed that the damage observed was due to the formation of thaumasite.

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Parameters affecting thaumasite formation in limestone cement mortar

Cement and Concrete Composites ◽

10.1016/s0958-9465(03)00119-7 ◽

2003 ◽

Vol 25 (8) ◽

pp. 977-981 ◽

Cited By ~ 20

Author(s):

G. Kakali ◽

S. Tsivilis ◽

A. Skaropoulou ◽

J.H. Sharp ◽

R.N. Swamy

Keyword(s):

Cement Mortar ◽

Limestone Cement

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Properties of Cement Mortars Mixed with SiO2 and CaCO3 Nanoparticles

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.539.244 ◽

2013 ◽

Vol 539 ◽

pp. 244-248

Author(s):

De Zhi Wang ◽

Yin Yan Zhang ◽

Yun Fang Meng

Keyword(s):

Compressive Strength ◽

Flexural Strength ◽

Cement Mortar ◽

Negative Impact ◽

Setting Time ◽

Water Requirement ◽

Mineral Admixtures ◽

Cement Pastes ◽

Optimal Replacement ◽

Cement Mortars

Water requirement of normal consistency, setting time and soundness of cement pastes mixed with SiO2 and CaCO3 nanoparticle and the flexural strength and compressive strength of cement mortars mixed with SiO2 and CaCO3 nanoparticles were experimentally studied. Results indicated that the added nano-SiO2 and nano-CaCO3 with a mass account of 4.0 wt. % decreased the setting time and increased the water requirement of normal consistency, flexural strength and compressive strength. And these nanoscaled mineral admixtures did not have a negative impact on cement soundness. The optimal replacement levels of cement by SiO2 and CaCO3 nanoparticles for producing cement mortar with improved strength were 2.0 and 4.0 wt.% respectively.

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