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Investigating the effect of cationic emulsified bitumen as an admixture of roller-compacted concrete pavement on the progress of alkali-silica reaction
Engineering Fracture Mechanics ( IF 4.7 ) Pub Date : 2021-05-01 , DOI: 10.1016/j.engfracmech.2021.107759
Seyed Vahid Pourjafar , Abolfazl Mohammadzadeh Moghaddam , Seyed Sajad Pourjafar , Maria Afsharirad

Alkali silica reaction (ASR) is one of the mechanisms that can reduce the durability of concrete. ASR causes concrete to swell, thereby creating internal stresses, which result in micro-cracking. This study investigated the impact of using rapid setting cationic bitumen emulsion (CRS) as an additive in roller-compacted concrete (RCC) on the progress of Alkali silica reaction (ASR). For this purpose, RCC specimens with different bitumen contents by weight of cement were prepared and subjected to ASR simulation conditions for one year. Length change, ultrasonic pulse velocity, and compressive strength tests were performed at the different ages (3, 7, 28, 90, 180, and 360 days). In addition, water absorption (WA) test, and Semi-circular bending (SCB) test at notch depths 19, 25 and 32 mm in loading mode I were performed, and thereby, the ASR-induced damage in terms of change in critical strain energy release rate (ΔJC) and water absorption (ΔWA) were also assessed. The results showed that as the bitumen content increased, the intensity of ASR progression decreased. In the control specimen (EAC0), a 0.1% increase in length, a 50% decrease in fracture toughness, and a 25% increase in water absorption due to ASR progress were observed, while for the specimen with 8% bitumen (EAC8), the results of 0.05% increase in length and 11% decrease in fracture toughness and 8% increase in water absorption were revealed. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDS) were performed to examine the microstructure of the specimens, as well. These examinations exhibited the fast progress of ASR and the extensive production of alkali-silica gel in the specimens without bitumen. However, in the mixture EAC8, aggregates near the bitumen-containing area revealed no trace of gel production, indicating that bitumen protects aggregates against ASR. One- and two-way analyzes of variance (ANOVA) performed at a 95% confidence level also confirmed the effectiveness of bitumen in preventing or reducing the intensity of ASR-induced damage in roller-compacted concrete.



中文翻译:

研究阳离子乳化沥青作为碾压混凝土路面掺合料对碱-硅反应进程的影响

碱二氧化硅反应(ASR)是可降低混凝土耐久性的机理之一。ASR使混凝土膨胀,从而产生内部应力,从而导致微裂纹。这项研究研究了在辊压密实混凝土(RCC)中使用速凝阳离子沥青乳液(CRS)作为添加剂对碱二氧化硅反应(ASR)进展的影响。为此,准备了具有不同水泥重量沥青含量的RCC标本,并在ASR模拟条件下进行了一年的测试。在不同年龄(3、7、28、90、180和360天)进行长度变化,超声脉冲速度和抗压强度测试。另外,在装载模式I下,在切口深度为19、25和32mm处进行了吸水(WA)测试和半圆形弯曲(SCB)测试,从而,C)和吸水率(ΔWA)也进行了评估。结果表明,随着沥青含量的增加,ASR进展的强度降低。在对照样品(EAC0)中,观察到由于ASR的进展,长度增加了0.1%,断裂韧性降低了50%,吸水率增加了25%,而对于含8%沥青的样品(EAC8),结果表明,长度增加了0.05%,断裂韧性降低了11%,吸水率增加了8%。还进行了扫描电子显微镜(SEM)和能量分散光谱(EDS)来检查样品的微观结构。这些检查显示了无沥青样品中ASR的快速发展和碱硅胶的大量生产。但是,在混合EAC8中,含沥青区域附近的骨料没有发现凝胶产生的痕迹,表明沥青可保护骨料免受ASR影响。在95%置信水平下进行的单向和双向方差分析(ANOVA)也证实了沥青在预防或减少碾压混凝土中ASR引起的破坏强度方面的有效性。

更新日期:2021-05-15
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