Matalkah Faris, Jaradat Yaser, Soroushian Parviz
Department of Civil Engineering, Yarmouk University, Irbid, 21163, Jordan.
Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI 48824, USA.
Heliyon. 2019 Apr 15;5(4):e01514. doi: 10.1016/j.heliyon.2019.e01514. eCollection 2019 Apr.
Restrained shrinkage cracking that appears on concrete surfaces during construction, or while concrete in the curing process adversely affect the long-term durability and other performance attributes of concrete-based-infrastructures. This study investigates the effects of early-age surface cracking on restrained shrinkage concrete made of alkali activated cement. Concrete produced using this class of cement differs from ordinary Portland cement concrete in terms of surface qualities and some other properties. Bleeding which could be a main cause of plastic shrinkage cracking was measured and compared with that of Portland cement. Rheological tests were performed to gain further insight into factors that may influence the early-age performance of the cement paste. Portland cement was used as control for comparative assessment of the alkali activated cement performance. Experimental test showed that alkali activated cement improved the characteristics of the newly produced concrete. The concrete prepared using alkali activated cement has low tendency to bleeding and higher resistance to plastic shrinkage, also, the viscosity and yield stress of the alkali activated cement paste were relatively higher when compared to those of ordinary Portland cement paste. Test data collected from rheological and bleeding tests on the alkali activated cement concrete were used to explain its desired resistance to plastic shrinkage cracking.
在施工过程中或混凝土养护过程中出现在混凝土表面的约束收缩裂缝，会对混凝土基础设施的长期耐久性和其他性能产生不利影响。本研究调查了早期表面裂缝对碱激活水泥制成的约束收缩混凝土的影响。使用这类水泥生产的混凝土在表面质量和其他一些性能方面与普通硅酸盐水泥混凝土有所不同。测量了可能是塑性收缩裂缝主要原因的泌水情况，并与硅酸盐水泥的泌水情况进行了比较。进行了流变试验，以进一步深入了解可能影响水泥浆体早期性能的因素。使用硅酸盐水泥作为对照，对碱激活水泥的性能进行比较评估。试验表明，碱激活水泥改善了新生产混凝土的特性。使用碱激活水泥制备的混凝土泌水倾向低，抗塑性收缩能力强，而且，与普通硅酸盐水泥浆体相比，碱激活水泥浆体的粘度和屈服应力相对较高。从碱激活水泥混凝土的流变和泌水试验中收集的试验数据用于解释其所需的抗塑性收缩裂缝能力。
