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In-Situ Production of Calcium Carbonate Nanoparticles in Fresh Concrete Using Pre-carbonation Method

机译：预碳化法在新鲜混凝土中原位生产碳酸钙纳米颗粒

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摘要

To reduce the carbon footprint of ordinary Portland cement (OPC)-based concrete, a novel technique, pre-carbonation process, has been developed to produce CaCO3 nanoparticles in fresh concrete. In this technique, gaseous CO2 is first absorbed into a slurry of calcium-rich minerals which is then blended with other ingredients to produce mortar/concrete. The objective of this work is to obtain an in-depth understanding of the underlying scientific mechanisms associated with the enhancement of strength and durability of the concrete induced by the new method. A comprehensive research plan has been carried out to study the carbonated slaked lime slurry and the effect of carbonated slaked lime slurry on the performance of OPC-based concrete, and to evaluate the potentials of the pre-carbonation method.;Experimental studies show that carbonating the calcium-rich mineral slurry with CO2 can produce CaCO3 nanoparticles and Ca(HCO 3)2 in the slurry, and these carbonation products were dictated by four parameters of the pre-carbonation method: the duration and temperature of the carbonation, the concentration of the calcium source slurry, and the stirring method of the calcium source slurry during the carbonation. The mechanical properties and durability of the mortar/concrete made with the carbonated slurry were significantly improved, which can be attributed to major mechanisms induced by the pre-carbonation method: promoted hydration of the cement and denser microstructure of the mortar/concrete. Calorimetry testing showed that the hydration of OPC was greatly improved by the pre-carbonation because of the extra heterogenous nucleation sites provided by the CaCO3 nanoparticles. XRD and TGA results revealed that more ettringite was produced in the mortar/concrete with pre-carbonated slaked lime slurry. The overall volume of the hydration products of the cement was increased by the pre-carbonation, leading to denser microstructure of the mortar/concrete.;It has been found that the pre-carbonation can be used to the OPC-supplementary cementitious materials (SCMs) blended cement mortar/concrete, as evidenced by the improved mechanical properties achieved by these mortars produced by using the pre-carbonation method. A preliminary study was also conducted to examine whether other calcium-rich minerals, such as Class C fly ash and limestone, can be used as calcium source in the pre-carbonation method.
机译：为了减少普通波特兰水泥（OPC）基混凝土的碳足迹，已经开发了一种新技术，即预碳化工艺，可以在新鲜混凝土中生产CaCO3纳米颗粒。在此技术中，首先将气态CO2吸收到富含钙的矿物浆液中，然后将其与其他成分混合以制成砂浆/混凝土。这项工作的目的是深入了解与新方法引起的混凝土强度和耐久性增强相关的基本科学机制。已经进行了全面的研究计划，以研究碳酸化熟石灰浆和碳酸化熟石灰浆对OPC基混凝土性能的影响，并评估预碳化方法的潜力。富含CO2的高钙矿物浆液可以在浆液中产生CaCO3纳米颗粒和Ca（HCO 3）2，这些碳酸化产物是由预碳酸化方法的四个参数决定的：碳酸化的持续时间和温度，碳的浓度。钙源浆，碳酸化过程中钙源浆的搅拌方法。用碳酸盐浆制成的砂浆/混凝土的机械性能和耐久性得到了显着改善，这可以归因于预碳化方法引起的主要机理：促进水泥的水合作用和砂浆/混凝土的致密微观结构。量热测试表明，由于碳酸钙纳米颗粒提供了额外的异质成核位点，预碳酸化大大提高了OPC的水合作用。 XRD和TGA结果表明，预碳酸化熟石灰浆在砂浆/混凝土中产生了更多的钙矾石。预碳化增加了水泥的水合产物的总体积，导致砂浆/混凝土的致密微观结构。现已发现，预碳化可用于OPC辅助胶结材料（SCM）。 ）混合水泥砂浆/混凝土，通过使用预碳化方法生产的砂浆可改善机械性能，证明了这一点。还进行了初步研究，以检查在预碳酸化方法中是否可以将其他富含钙的矿物质（例如C类粉煤灰和石灰石）用作钙源。

著录项

  • 作者

    Qian, Xin.;

  • 作者单位

    The University of Alabama.;

  • 授予单位 The University of Alabama.;
  • 学科 Civil engineering.;Materials science.
  • 学位 Ph.D.
  • 年度 2017
  • 页码 141 p.
  • 总页数 141
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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