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Enhanced reactive magnesia cement-based concrete mixes

A technology of magnesium oxide and magnesium hydroxide, applied in the production of magnesium oxide, magnesium hydroxide, cement, etc., can solve the problems of low reactivity and availability, low reaction degree, low diffusion rate, low efficiency and so on

Active Publication Date: 2019-11-12
NANYANG TECH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The first is the low degree of reactivity related to the reactivity and availability of the unreacted phase
The second is CO 2 Low diffusion rate in cement matrix
These limitations in the hydration and carbonation of RMC lead to its ineffective use as a binder and limit the strength development of RMC-incorporated concrete formulations

Method used

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  • Enhanced reactive magnesia cement-based concrete mixes
  • Enhanced reactive magnesia cement-based concrete mixes
  • Enhanced reactive magnesia cement-based concrete mixes

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0146] Example 1: Materials

[0147] The primary cement binder used in the various examples herein was RMC (trade name "calcined magnesite 92 / 200") produced at approximately 1000°C obtained from Richard Baker Harrison, UK. 200)"). The chemical and physical properties of RMC are shown in Table 1 below.

[0148] Table 1-The chemical composition and physical properties of RMC

[0149]

[0150] *R 2 o 3 : Fe 2 o 3 and Al 2 o 3

[0151] The reactivity of the RMC (ie, measured by the time required to neutralize 0.25M acetic acid with 5 grams of RMC) was recorded as 520 seconds. Magnesium acetate ((CH 3 COO) 2 Mg) acts as HA to facilitate the hydration process. Using a specific surface area obtained from Fisher Scientific (Fisher Scientific, UK) with a specific surface area of ​​43.5 m 2 / g hydromagnesite seeds to provide additional nucleation sites and stimulate the nucleation and growth of HMCs in the pore space. figure 1 The microstructure of hydromagnesite see...

Embodiment 2a

[0152] Example 2a: General Example of the Process of the Invention

[0153] The method of the present invention first prepares a solution by dissolving a predetermined amount of HA in water (for example, at a concentration of 0M to 0.1M), and then seeds (for example, 0 weight percent (wt%) to 2wt% magnesium oxide-based cement and seeds) were introduced into the solution. The seeds were allowed to disperse in the solution by stirring using a magnetic stirrer at ambient temperature (eg, 30±3°C) for 5 minutes. When subsequently added to the RMC, the seeds in the solution were stirred to allow them to disperse evenly within the pores of the RMC. The well mixed solution can then be introduced into the RMC to form a paste. In some cases, coarse aggregate can then be added to the paste to complete the production of the concrete mix. The cast samples were then compacted and subjected to carbonization.

Embodiment 2b

[0154] Example 2b: General Characterization

[0155] Isothermal calorimetry characterization was performed on the samples in each of the examples below. The heat flow due to the hydration of each mixture was studied at 30°C by an I-Cal 8000 high precision calorimeter according to ASTM C1702-15a. The preparation of the paste involves dispersing the seed crystals in H 2 O or HA, the H 2 O or HA was preheated to 30 °C in order to produce samples at the same temperature as the measurement temperature. The seeded solution was then mixed with RMC. After mixing for about 15 to 20 seconds, the prepared paste was placed into an isothermal calorimeter channel to measure the heat of hydration.

[0156] For the water absorption test, each sample was measured after 14 and 28 days of carbonization. Record the initial mass of the sample before immersing it in the water tank. Absorbent mass is also measured when the sample reaches a constant mass under water, which reflects its abilit...

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Abstract

According to the present disclosure, a method of producing a hydrated magnesium carbonate based cement composite (HMCs) is provided. The method comprising providing an aqueous solution comprising a hydration agent and hydrated magnesium carbonate seed particles; contacting the aqueous solution with a magnesium oxide based cement to form magnesium hydroxide from the hydration agent and the magnesium oxide based cement, and on the hydrated magnesium carbonate seed particles; and exposing the magnesium hydroxide to carbon dioxide to form the hydrated magnesium carbonate based cement composite. The use of hydration agent and seed particles not not only increases formation of HMCs but also improves the mechanical performance of RMC based concrete formulations.

Description

[0001] Cross References to Related Applications [0002] This application claims priority from Singapore Patent Application No. 10201700636V filed on 25 January 2017, the entire contents of which are incorporated herein by reference for all purposes. technical field [0003] The present invention relates to a method for producing cement composites based on hydrated magnesium carbonate. The invention also relates to a cement composite based on hydrated magnesium carbonate. Background technique [0004] Carbon dioxide (CO2) emitted from the combustion of fossil fuels 2 ) concentration is a major environmental problem. The Portland cement (PC) industry is considered a CO 2 One of the major contributors to increased emissions, as global PC production of more than 4 billion tons per year contributes 5% to 10% of global anthropogenic CO 2 emissions and a large amount of resource consumption. The amount of energy consumed by this process is about 2780 to 3050 terawatt hours p...

Claims

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Application Information

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IPC IPC(8): C01F5/24C04B9/20C01B32/60C04B7/36C01F5/02C01F5/14
CPCC04B28/105C04B20/008C04B22/10C04B24/04C04B40/0231C04B22/0086C04B22/124C04B22/122
Inventor 赛斯·恩鲁尔阮天容
Owner NANYANG TECH UNIV
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