Power-Ultrasound as a tool for sustainable concrete production - first upscaling of laboratory experiments

DFG资助的基础研究“功率超声对水泥悬浮液流动和固化行为的影响”表明，PUS在生产混凝土方面具有巨大的潜力。在会议和期刊上发表的结果引起了工业和研究的极大兴趣。必须指出的是，所有以前的研究都是在实验室规模上进行的。到目前为止，FIB /魏玛大学提供的超声波处理器不允许我们对混凝土混合物进行超声处理，即到目前为止，仅对用于制备砂浆配方的水泥悬浮液进行超声处理。为了提供有关实践中结果可转移性的可靠信息，缺少中试规模试验以及预制和预拌混凝土生产中技术测试的转移（所谓的“高档”-尝试）。拟议的项目将在试验规模上进行测试。这意味着寻求具有专门设计的泵电路的高功率超声波发生器，其允许对更大体积的水泥悬浮液进行超声处理，从而导致生产混凝土的有效且相关的方式。从超声水泥悬浮液混凝土棒铸造和测试的工作性，强度发展，耐久性和变形行为。将这些结果与以标准方式和已知悬浮技术混合的相应混凝土的结果进行比较，使我们能够评估PUS对混凝土特性的优点和可能的缺点。在此基础上，我们将决定PUS是否是一种可用于实践的处理方法，以及PUS是否应在技术测试中应用于混凝土（即在预制厂和预拌混凝土生产中）。拟议项目的第一个目标是优化PUS混合参数，如泵送回路中的压力、超声功率和振幅，以获得混凝土早期强度的最大加速。第二部分对新拌混凝土的性能、孔结构、强度、变形性能和耐久性（常规搅拌法、悬浮法和PUS-Mix法）进行了比较。在调查的第三部分中，如第一部分中所定义的最佳声音状态（泵压和PUS -性能）用于增加五种标准混凝土的早期强度（在恒定的可加工性下）。混凝土的成分设计成这样，即可以评估PUS是否能够在降低水泥强度等级的情况下确保恒定的混凝土强度（这可以节省研磨能量）。另一方面，将考虑PUS是否能够通过用粉煤灰、矿渣或石灰石替代波特兰水泥熟料来节省水泥熟料。

DFG-funded basic research on "Impact of power ultrasound on the flow and solidification behavior of cement suspensions" showed that PUS has a great potential for the production of concrete The presentation of results at conferences and in journals encountered a great deal of interest from industry and research. Limiting must be said that all previous studies were performed on a laboratory scale. Up to date the ultrasonic processor available at the FIB /University of Weimar does not allow us to sonicate concrete mixes, i.e. so far only cement suspensions for preparing mortar formulations were sonicated. In order to provide sound information on the transferability of the results in the practice, trials at pilot scale and the transfer of technical tests in the precast and ready mix concrete production are missing (so called "upscale" - attempts). The proposed project will be carried out tests on a pilot scale. This means a high power ultrasound generator with a specially designed pump circuit is sought that allows to sonicate cement suspensions on bigger volumes, thus leading to an efficient and relevant way to produce concrete. From the sonicated cement suspensions concrete bars are casted and tested for workability, strength development, durability and deformation behavior. Comparing these results with those of the corresponding concretes mixed in a standard manner and by the known suspension technology enables us to evaluate advantages and maybe disadvantages on PUS on concrete characteristics. On this basis we will then decide whether PUS is a recommendable treatment for practice and if PUS should be applied to concrete in a technical test (i.e. in precasting plant and in ready mix concrete production).The first target in the proposed project is to optimize the PUS mixing parameters such as pressure in the pumping circuit, ultrasound power and amplitude to obtain a maximum acceleration of the concrete early strength. In the second section the properties of fresh concrete, the pore structure, the strength, the deformation behavior and the durability of concrete (by conventional mixing techniques, suspension and PUS-mixing method) are compared. In the third part of the investigations optimum sound regime (pump pressure and PUS - performance) as defined in the first part are used to increase the early strength of five standard concretes (at constant workability). The composition of the concrete is designed in such a way, that it can be evaluated whether PUS is capable to ensure constant concrete strength at reduced cement strength class (which allows saving of grinding energy). On the other hand, it will be considered whether PUS enables saving of Portland cement clinker by replacing it by fly ash, slag or limestone.