Basalt fiber reinforced foam concrete with marble waste and calcium aluminate cement

As a typical cellular lightweight material, foam concrete is produced by mixing cement, water, aggregate and a suitable foaming agent and has a density usually below 1600 kg/m(3). The large number of air spaces present in foam concrete ensures that the concrete has advantages such as lightweight, high fluidity during pouring, excellent thermal and sound insulation, superior fire resistance, and outstanding energy absorption capacity. Its high porosity and the connectivity of the pores, which can allow the entry of negative substances into the concrete environment, cause foam concrete to have a very low physico-mechanical and durability performance. To eliminate or reduce these disadvantages, this study adopted the use of basalt fibers (BF) as eco-friendly fiber type and calcium aluminate cement (CAC) as aluminous cement with waste marble powder (WMP) as aggregates in foam concrete. In that respect, 9 mixes with varying content of foaming agent (FC) and basalt fiber have been prepared. Assessment of mechanical performance was based on compressive and flexural strength after 6 h, 1, 7, and 28 days. Dry bulk density, thermal conductivity, porosity, water absorption, and sorptivity of the concretes were determined. Durability characteristics of the concretes were examined by dry shrinkage, high temperature, magnesium sulfate, sulfuric, and hydrochloric acids. The obtained results showed that the content of BF affected the compressive strength of the mixtures slightly negatively or positively depending on the FC. The lowest value in thermal conductivity was gained as 0.645 (W/m K) for the mixture incorporating 1% BF and 50 kg/m(3) foam quantity. In addition, the foam concrete incorporating foam of 30 kg/m(3) and 1% BF showed the best resistance against MgSO4. The mixture with 2% BF and 30 kg/m(3) FC exhibited the lowest mass loss after HCI exposure.

Automated summary

Foam concrete is a lightweight material with excellent thermal insulation and energy absorption capacity. However, its high porosity and pore connectivity lead to low physico-mechanical and durability performance. This study used basalt fibers and calcium aluminate cement to improve the properties of foam concrete, and evaluated its mechanical performance, thermal conductivity, and durability under various conditions.