Behavior of Natural Pozzolana-Lime-stabilized Clayey Soils Artificially Contaminated by Sulfates

IF 1 Q4 ENGINEERING, CIVIL
Hamid Gadouri
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引用次数: 0

Abstract

The use of lime in sulfate-bearing clayey soils has historically caused structural damage to infrastructures due to the formation of an expansive ettringite mineral. In this paper, a research was conducted to study the effectiveness of natural pozzolana (NP) for providing better stabilization of sulfate-bearing soils. Compaction and free-swell potential tests were first performed on lime-stabilized grey and red clayey soils (GS and RS) containing different contents of added sodium and calcium sulfates (2, 4 and 6% Na2SO4 or CaSO4·2H2O). Then, the same tests were repeated by adding 20%NP. The test results indicated that the presence of 4% and 6% Na2SO4 in the soil resulted in an abnormal increase in the swell potential of both lime-stabilized GS and RS. The X-ray diffraction (XRD) results confirmed the growth of the ettringite mineral responsible for this higher swell potential. However, the use of 8% lime with 20%NP in stabilizing sulfate-bearing clayey soils produced significant improvements in the optimum moisture content (OMC) and maximum dry density (MDD), as well as in the swell potential. The addition of 20%NP into the lime-stabilized GS and RS eliminated the harmful effect of Na2SO4. In addition, for 120-day curing period, the use of 6% CaSO4·2H2O was found very effective by reducing the swell potential of NP-lime-stabilized GS and RS from 7.33% to 0.4% and from 2.79% to 0.2%, respectively trips. KEYWORDS: Clayey soils, Mineral additives, Sulfates, Compaction, Swell potential, Stabilization.
硫酸盐人工污染天然灰泥稳定粘土的特性研究
在含硫酸盐的粘土中使用石灰,由于形成膨胀的钙矾石矿物,历来会对基础设施造成结构性破坏。本文研究了天然灰火山灰(NP)对含硫酸盐土壤的稳定性。首先对添加不同硫酸钠和硫酸钙(2,4和6% Na2SO4或CaSO4·2H2O)的石灰稳定灰粘土和红粘土(GS和RS)进行了压实和自由膨胀电位试验。然后,通过添加20%的np重复相同的测试。结果表明,土壤中Na2SO4含量分别为4%和6%导致石灰稳定GS和RS膨胀势异常增大,x射线衍射(XRD)结果证实了钙矾石矿物的生长导致了这种高膨胀势。然而,在稳定含硫酸盐粘土中,使用8%石灰和20%NP,在最佳含水量(OMC)和最大干密度(MDD)以及膨胀势方面都有显著改善。在石灰稳定的GS和RS中加入20%的np可以消除Na2SO4的有害影响。此外,在120天的养护期内,6%的CaSO4·2H2O的使用非常有效,可以将硝酸石灰石稳定的GS和RS的膨胀势分别从7.33%降至0.4%和2.79%降至0.2%。关键词:粘性土,矿物添加剂,硫酸盐,压实,膨胀势,稳定
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来源期刊
CiteScore
2.10
自引率
27.30%
发文量
0
期刊介绍: I am very pleased and honored to be appointed as an Editor-in-Chief of the Jordan Journal of Civil Engineering which enjoys an excellent reputation, both locally and internationally. Since development is the essence of life, I hope to continue developing this distinguished Journal, building on the effort of all the Editors-in-Chief and Editorial Board Members as well as Advisory Boards of the Journal since its establishment about a decade ago. I will do my best to focus on publishing high quality diverse articles and move forward in the indexing issue of the Journal.
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