Aubert J E, Husson B, Vaquier A
Laboratoire Matériaux et Durabilité des Constructions, INSA-UPS, 135 avenue de Rangueil, 31077 Toulouse Cedex 4, France.
Waste Manag. 2004;24(6):589-96. doi: 10.1016/j.wasman.2004.01.005.
This article focuses on the effects of metallic aluminum contained in municipal solid waste incineration (MSWI) fly ashes on cement-based materials in which they are added. The ash under study was treated by an industrial physicochemical process of neutralization. The paper also presents a method to quantify the metallic aluminum content of ash: it consists in measuring the amount of hydrogen gas produced by the oxidation reaction of metallic aluminum. This method is simple and fast. Results show that studied ash contains an appreciable amount of metallic aluminum. Investigations were carried out to study the incorporation of the ash in concrete: in this case, the presence of metallic aluminum is worrying because it could be responsible for disorders in concrete. In fact, swellings are observed on cement pastes and mortars containing ash during the first 24 h of hydration. A test based on hydrostatic weighing permits to quantify the swelling of fresh cement paste and to study the evolution of this swelling. Causes of swelling are analyzed. Results show that ettringite formation occurs after the end of the expansion reaction. So it can be concluded that metallic aluminum is the sole responsible for the observed swelling. Consequences of swelling are also analyzed by measuring compressive strength of ash-containing mortars: this swelling leads to cracks in the mortars and significant decrease of their compressive strength.
本文重点研究城市固体废弃物焚烧（MSWI）飞灰中所含金属铝对添加该飞灰的水泥基材料的影响。所研究的飞灰采用工业物理化学中和工艺进行处理。本文还提出了一种量化飞灰中金属铝含量的方法：该方法是测量金属铝氧化反应产生的氢气量。此方法简单快捷。结果表明，所研究的飞灰含有相当数量的金属铝。开展了将飞灰掺入混凝土的研究：在这种情况下，金属铝的存在令人担忧，因为它可能导致混凝土出现问题。事实上，在含灰水泥浆体和砂浆水化的最初24小时内观察到了膨胀现象。基于静水称重的试验能够量化新拌水泥浆体的膨胀量，并研究这种膨胀的发展过程。分析了膨胀的原因。结果表明，钙矾石在膨胀反应结束后形成。因此可以得出结论，金属铝是观察到的膨胀现象的唯一原因。通过测量含灰砂浆的抗压强度，也分析了膨胀的后果：这种膨胀导致砂浆出现裂缝，并使其抗压强度显著降低。
