Title:
Workability of Low-Clinker Mortars with Recycled Fine Aggregates and Different Polymers as Superplasticizer
Author(s):
Mareike Thiedeitz, Noah Tarrab Maslaton and Thomas Kränkel
Publication:
Symposium Paper
Volume:
362
Issue:
Appears on pages(s):
147-163
Keywords:
low clinker concrete, recycled aggregates, SCMs, workability
DOI:
10.14359/51740880
Date:
6/5/2024
Abstract:
The use of recycled aggregates in concrete has gained popularity due to its contribution to the reduction of primary resource extraction. In Germany, the use of recycled fine aggregates is not standardized while recycled aggregates larger than 2 mm can be used in concrete depending on their origin, exposure class, and humidity class. In this research framework, we investigated the workability, mechanical, and durability performance of low-clinker mortars using recycled fine aggregates compared to natural sands. Three polycarboxylate ether-based superplasticizers, differing in their polymer structure (chain lengths and charging density) were tested to achieve a comparable initial workability. Four mortar test series with recycled fine aggregates were analyzed with different supplementary cementitious materials to keep the clinker amount low. The initial water demand, presoaking of recycled aggregates, and the workability over time were tested. The workability of low-clinker mortars with recycled aggregates, analyzed through slump flow measurements, proved comparable results to natural aggregates once mixture proportions and superplasticizer type and content were adjusted. However, mechanical tests on mortars with optimized workability properties showed decreased compressive strength and increased capillary suction when using recycled fine aggregates and supplementing cement. An optimized workability procedure for enhanced mechanical properties is still ongoing research. The results are the basis for further mortar and concrete mixture optimizations to reach high-performance low-clinker mortars and concrete with recycled aggregates.