کد مقاله کد نشریه سال انتشار مقاله انگلیسی ترجمه فارسی نسخه تمام متن
10621928 989038 2011 10 صفحه PDF سفارش دهید دانلود رایگان
عنوان انگلیسی مقاله ISI
Characterization of aerial lime-based mortars modified by the addition of two different water-retaining agents
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موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی صنعتی و تولید
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Characterization of aerial lime-based mortars modified by the addition of two different water-retaining agents
چکیده انگلیسی
Two different commercial additives that have been reported to act as viscosity enhancing, water retaining admixtures, namely hydroxypropyl methylcellulose and a guar gum derivative, were added to lime-based mortars in order to test their performance. Different properties of lime-based mortars were evaluated: fresh mixture behaviour through water retention, air content and setting time; hardened mixtures properties such as density, shrinkage, water absorption through capillarity, water vapour permeability, long-term compressive strengths, pore structure through mercury intrusion porosimetry and durability assessed by means of freezing-thawing cycles. Hydroxypropyl methylcellulose, unlike its well-known effect in cement-based materials, showed a very limited viscosity enhancing behaviour in aerial lime mortars. An adsorption mechanism of this additive on the Ca(OH)2 crystals was reported to reduce its entanglement between chains and hence the viscosity of the pastes as well as its water retention ability. The guar gum derivative, which has a larger quantity of ionized groups at alkaline pH, reduced its adsorption onto slaked lime particles and gave rise to a clear increase in viscosity. However, this involved a larger water-retention capacity, which in fact resulted in a delay in setting time. The guar gum derivative proved to raise the air content, and changed the pore size distribution of the hardened mortars, thus improving the water absorption through capillarity and durability in the face of freezing-thawing cycles.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Cement and Concrete Composites - Volume 33, Issue 2, February 2011, Pages 309-318
نویسندگان
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