Odhiambo Vincent Odhiambo, Scheinherrová Lenka, Abuodha Silvester Ochieng, Mwero John Nyiro, Marangu Joseph Mwiti
Department of Civil and Construction Engineering, University of Nairobi, Nairobi 00100, Kenya.
Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague, Czech Republic.
Materials (Basel). 2022 Dec 14;15(24):8935. doi: 10.3390/ma15248935.
Sulfate attack in concrete structures significantly reduces their durability. This article reports the experimental findings on the effects of sodium sulfate on limestone calcined clay cement (LC) in an alternate wet and dry media. The samples underwent wet-dry conditions of 28 cycles. Two types of LC were studied, one made from clay (LC-CL) and the other made from fired rejected clay bricks (LC-FR). The composition of each LC blend by weight was 50% clinker, 30% calcined clay, 15% limestone, and 5% gypsum. The reference compressive strength was evaluated at 2, 7, and 28 days of age. Then, ordinary Portland cement (OPC) and LC-CL blends were subjected to alternate wet-dry cycle tests, immersion in a 5% sodium sulfate solution, or in water. For all exposed samples, sorptivity tests and compressive strength were done. The results showed that LC blends met the requirements for KS-EAS 18-1:2017 standard, which specifies the composition and conformity criteria for common cements in Kenya. The LC blend also had a lower rate of initial absorption compared to OPC. Additionally, LC blend also showed good resistance to sodium sulfate when exposed to alternating wetting and drying environment. OPC showed higher compressive strength than LC blends for testing ages of 2, 7, and 28 days. However, the LC samples utilized in the sodium sulfate attack experiment, which were later tested after 84 days, exhibited higher compressive strengths than OPC tested after the same period.
混凝土结构中的硫酸盐侵蚀会显著降低其耐久性。本文报道了在干湿交替介质中硫酸钠对石灰石煅烧粘土水泥（LC）影响的实验结果。样品经历了28个干湿循环条件。研究了两种类型的LC，一种由粘土制成（LC-CL），另一种由废弃烧粘土砖制成（LC-FR）。每种LC混合物按重量计的组成是50%熟料、30%煅烧粘土、15%石灰石和5%石膏。在龄期2天、7天和28天时评估参考抗压强度。然后，对普通硅酸盐水泥（OPC）和LC-CL混合物进行干湿循环试验、浸泡在5%硫酸钠溶液或水中。对所有暴露的样品进行了吸水性试验和抗压强度测试。结果表明，LC混合物符合KS-EAS 18-1:2017标准的要求，该标准规定了肯尼亚普通水泥的组成和合格标准。与OPC相比，LC混合物的初始吸水率也较低。此外，在干湿交替环境中暴露时，LC混合物对硫酸钠也表现出良好的抗性。在2天、7天和28天的测试龄期，OPC的抗压强度高于LC混合物。然而，在硫酸钠侵蚀实验中使用的LC样品，在84天后进行测试时，其抗压强度高于同期测试的OPC。
