Studying the hardening and mechanical performances of rice husk and hemp-based building materials cured under natural and accelerated carbonation.
Studying the hardening and mechanical performances of rice husk and hemp-based building materials cured under natural and accelerated carbonation.
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DOI：
10.1016/j.conbuildmat.2015.06.032
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发表时间：
2015-09
影响因子：
7.4
通讯作者：
M. Chabannes;E. Garcia-Diaz;L. Clerc;J. Benezet
中科院分区：
文献类型：
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作者：
M. Chabannes;E. Garcia-Diaz;L. Clerc;J. Benezet
本文研究了稻壳、大麻秆制成的绿色混凝土的力学性能和石灰基胶凝材料的硬化。混凝土试件进行了不同的养护条件。在自然碳酸化条件下，试样在10个月内在气候控制室（20 °C - 50%RH）或暴露在室外进行固化。研究了加速碳化养护（CO2养护）对混凝土材料短期（1-2个月）抗压强度的影响，并在自然碳化10个月前和CO2养护后的不同时间进行了抗压强度试验。粉末状基质样品收集在散装和表面上的标本，调查碳化和水化的粘结剂通过热分析和酚酞测试被用来提供有关的碳化深度的信息。在自然碳化，结果表明，石灰基粘结剂几乎硬化以相同的方式为两种混凝土具有相似的碳化率。但稻壳混凝土的力学性能随时间的推移表现出天花板效应，这是由于稻壳与石灰之间的结合强度较低。至于暴露在室外的试样，由于更有利的碳化湿度条件，强度随时间的增加更为显着。加速碳化养护可在短期内提高混凝土的力学性能。CO2固化后的抗压强度大致相当于在自然碳酸化条件下户外暴露10个月后获得的抗压强度。
The purpose of this paper is to investigate the mechanical properties and the lime-based binder hardening of green concretes made of rice husk or hemp hurd. Concrete specimens were subjected to different curing conditions. Under natural carbonation, specimens were cured during 10 months either in a climate-controlled room (20 °C – 50%RH) or exposed outdoors. The work also focused on an accelerated carbonation curing (CO2curing) aiming to improve the short term compressive strength (1–2 months) of the concrete materials.Compressive strength tests were conducted at different dates until 10 months of natural carbonation and after CO2curing. Powdered matrix samples were collected in the bulk and on the surface of the specimens to investigate carbonation and hydration of the binder by thermal analysis and a phenolphthalein test was used to provide information about the carbonation depth.Under natural carbonation, the results indicated that the lime-based binder was almost hardened in the same way for both concretes with a similar rate of carbonation. However, the rice husk concrete was characterized by a ceiling effect of mechanical performances over time, which was attributed to the lower bonding strength between rice husks and lime. Concerning specimens exposed outdoors, the strength gain over time was more significant owing to more favorable humidity conditions for carbonation. The accelerated carbonation curing led to an increase of mechanical properties of the concretes in the short term. The compressive strength after CO2curing was approximately equivalent to those obtained after 10 months of outdoor exposure under natural carbonation.