The current study investigates the effect of shrinkage reducing admixtures (SRA) on volume changes that may lead to shrinkage cracking and early age cracking. Drying shrinkage (DS) and autogenous deformation (AD), the impetus for shrinkage cracking, were measured over 2.5 years for three concretes with and without 1% SRA addition: an ordinary Portland concrete, a fly ash concrete and a slag concrete. The latter two concretes were also tested in the Temperature‐stress testing machine (TSTM), which measures AD, thermal dilation (TD) and restrained stress development for a concrete subjected to realistic temperature curing conditions. SRA was found to have a substantial and permanent impact on DS and AD for all three concretes (up to 32% reduction of the total deformation after 2.5 years). The higher the shrinkage, the higher the effect of SRA. For the slag concrete, where AD was found to be the main impetus of early age volume changes, SRA had a clear beneficial effect on the cracking tendency. For the fly ash concrete, where TD provided the main contribution to the volume changes, SRA had a less pronounced effect. The test results were also compared with AD and DS modeled by Model Code 2010.

中文翻译：

---

减缩剂对混凝土的干缩，自生变形和早期应力发展的影响

目前的研究调查了减缩剂（SRA）对体积变化的影响，该变化可能导致收缩开裂和早期开裂。2.5年内，对三种添加和不添加1％SRA的混凝土进行了干缩（DS）和自生变形（AD）的测量，这些都是收缩开裂的动力：普通硅酸盐混凝土，粉煤灰混凝土和矿渣混凝土。后两种混凝土也在温度应力试验机（TSTM）中进行了测试，该试验机测量了经受实际温度固化条件的混凝土的AD，热膨胀（TD）和约束应力的发展。发现SRA对所有三种混凝土的DS和AD都有实质性和永久性的影响（2.5年后总变形降低了32％）。收缩率越高，SRA的效果越好。对于矿渣混凝土，发现AD是早期体积变化的主要推动力，而SRA对开裂趋势具有明显的有利影响。对于粉煤灰混凝土，运输署对体积变化起主要作用，而SRA的影响不那么明显。还将测试结果与由Model Code 2010建模的AD和DS进行了比较。