Mohammad Mastali

Carbon dioxide sequestration of fly ash alkaline-based mortars containing recycled aggregates and reinforced by hemp fibers: Properties, freeze-thaw resistance, and carbon footprint

The authors would like to acknowledge the financial support of the Foundation for Science and Technology (FCT) in the frame of project IF/00706/2014-UM.2.15.

Carbon dioxide sequestration of fly ash alkaline-based mortars containing recycled aggregates and reinforced by hemp fibers: Mechanical properties and numerical simulation with a finite element method

The authors would like to acknowledge the financial support of the Foundation for Science and Technology (FCT) in the frame of project IF/00706/2014-UM.2.15.

Carbon dioxide sequestration on fly ash/waste glassalkali-based mortars with recycled aggregates: Compressive strength, hydration products, carbon footprint, and cost analysis

The authors would like to acknowledge the financial support of the Foundation for Science and Technology (FCT) in the frame of project IF/00706/2014-UM.2.15.

Comparative Study on the Drying Shrinkage and Mechanical Properties of Geopolymer Foam Concrete Incorporating Different Dosages of Fiber, Sand and Foam Agents

A recent innovation, geopolymer foam concrete (GFC), combines the advantages of geopolymer technology and foam concrete, and provides the opportunity to reduce the environmental footprint of construction materials in terms of raw materials, embodied CO2 and operational energy in service. Foam concrete is generally defined as a type of lightweight concrete that consists of a cementitious binder with a high degree of void space, with or without the addition of fine aggregate. One of the main drawbacks of these materials is high drying shrinkage. This paper presents an extensive experimental study to reduce the drying shrinkage in foam geopolymer concrete. Moreover, mechanical properties of foam geopolymer concrete were characterized by compressive and flexural strengths. To reduce the drying shrinkage in foam geopolymer concretes different strategies used, including foam content (0.2%, 0.5%, 0.8%), sand/binder content (0.30, 0.35, 0.40, 0.45, 0.50, 0.75, 1.00, 1.25, 1.50), and using polypropylene (PP) fibers with different lengths (6 mm and 20 mm) and fiber volume fractions (0.2%, 0.6%, 1%, and 1.4%). The obtained results showed that increasing sand content up to 50% reduced the drying shrinkage, while the drying shrinkage increased above this sand content. Additionally, increasing foam content intensified the increase of drying shrinkage. This increase was proportional to foam content. In general, regardless of fiber type and content, reinforcement of foam geopolymer concrete reduced the drying shrinkage and enhanced mechanical properties.

Structural performance of hybrid sandwich slabs under shear loading

In a hybrid panel with glass fiber-reinforced polymer (GFRP) bottom skin and ribs, and deflection hardening cementitious composites (DHCC) top layer, it is very important to provide good shear connection between these various components in order to increase the load carrying capacity of the resulting hybrid slabs and a larger increment of deflection before the occurrence of the structural softening of this panel. The effectiveness of the proposed hybrid sandwich panels strongly depends on the performance of the shear connectors. The efficiency of indented shear connectors in improving the flexural performance of hybrid sandwich panels is here demonstrated. Since the efficiency of indented shear connectors in the hybrid sandwich panels is unknown, efforts are made in this paper in investigating the shear performance of hybrid slabs. A special focus is given on the indented shear connector’s behavior, considering different shear span ratios in ranges of 2.00, 1.39, and 0.77. In this regard, six hybrid sandwich panels were manufactured and experimentally tested under different shear loads. Then, the results are interpreted comprehensively. The results obtained show that the GFRP rib thickness and height, and shear span ratios influence the damage events and the structural performance of the hybrid sandwich panels. Moreover, it was observed that using indented shear connectors in the hybrid slabs, regardless of the shear span ratios, provides high load capacity, high stiffness, and large residual deflection.