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The purpose of this paper is to examine the use of phragmites australis ash (PAA) in cementitious systems to achieve sustainable construction.

In this paper, the properties of mortar containing PAA as partial cement replacement are determined. The PAA is produced through slow burning in a closed system to minimize the CO₂ emission. A total of four mortar mixes are prepared with PAA replacement levels ranging from 0% to 30% by weight. The water to binder and the proportions of binder to sand are 0.55 and 1:3 by weight, respectively. The properties tested are density, compressive strength, flexural strength, ultrasonic pulse velocity, water absorption by total immersion and capillary rise. Testing is conducted at 1, 7, 28 and 90 days.

While there is a decrease in strength as the amount of PAA increases, there is strong indication of pozzolanic reaction in the presence of PAA. This is in agreement with the results reported by Salvo et al. (2015), where they found noticeable pozzolanic activities in the presence of straw ash, which is rich in SiO₂ and relatively high K₂O content. At 90 days of curing, there is a decrease of 5% in compressive strength at 10% PAA replacement. However, at 20% and 30% replacement, the reduction in compressive strength is 23% and 32%, respectively. The trend in flexural strength and ultrasonic pulse velocity is similar to that in compressive strength. The water absorption by total immersion and capillary rise tends to increase with increasing amounts of PAA in the mix. There seems to be a linear relationship between water absorption and compressive strength at each curing age.

The Phragmites australis plant used in this investigation is obtained from one location and this present a limitation as the type of soil may change the properties. Also one method of slow burning is used. Different burning methods may alter the composition of the PAA.

This outcome of this research will contribute towards sustainable development as it will make use of the waste generated, reduce the amount of energy-intensive cement used in construction and help generate local employment in the area where the Phragmites australis plant grows.

To the best knowledge of the authors, the ash from the Phragmites australis plant has not been used in cementitious system and this research can be considered original as it examines the properties of mortar containing PAA. Also, the process of burning in a closed system using this material.

The purpose of this paper is to concern with using municipal solid waste incineration bottom ash (MSWI-BA) in concrete application.

In this paper, the performance of reinforced concrete (RC) beams containing MSWI-BA was investigated. Four concrete mixes were used in this study. The control mix had a proportion of 1 (cement): 2 (fine aggregates): 4 (coarse aggregates) by weight. In the other three mixes, the fine aggregates were partially replaced with 20%, 40% and 60% MSWI-BA (by weight). The water to cement ratio was kept constant at 0.5 in all mixes. Concrete cubes and cylinders were prepared to determine some physical and mechanical properties of concrete, whereas RC beams were used for determining the structural performance.

There was an increase in compressive strength, tensile strength and the modulus of elasticity when 20% of fine aggregates were replaced with MSWI-BA. However, beyond 20% these properties were reduced. The load bearing capacity and deflection were the highest for the control beam and the beam with 20% MSWI-BA.

The research conducted in this investigation used a specific type of MSWI-BA. The composition of the waste can vary from one plant to another and this presents one of the limitations.

The findings of this research indicate that MSWI-BA can partially substitute fine aggregate, thus reducing the impact of construction on the environment.

The MSWI-BA used in this research differs from other types as the waste papers and cartons are removed from the waste and used to produce other products. Therefore, this study is considered original as it examines MSWI-BA with different properties for use in construction.