Fresh, mechanical and durability properties of sustainable cement grouts incorporating dredged materials from UAE dams

Abstract

The paper proposes the use of dam dredged materials (DDM) in the construction industry in the United Arab Emirates (UAE). The used DDM in this study were collected from a prominent dam in UAE. Four cement grout mixes were prepared by replacing aggregates with the following percentages of DDM: 0 %, 3 %, 5 % and 10 %. The fresh, mechanical and durability performance of the grout mixes were examined. The slump and rheology of the prepared grout mixes were measured over two hours, with one-hour intervals between two successive measurements. The rheology was assessed by conducting shear flow and stress growth tests. Further, air content, fresh bulk density and initial setting time were measured for all mixes. The mechanical properties were evaluated through measuring the compressive strength and hardened density at 7, 28, 56 and 90 days. Additionally, shrinkage, electrical conductivity and electrical resistivity were measured to assess the durability of the prepared mixes. The results showed that the dam dredged materials enhanced the mechanical and durability of the tested grouts. For example, the 28-day strength increased by approximately 40 % when DDM content was increased from 0 % to 10 %. Further, the DDM offset the shrinkage of the grouts, and shrinkage decreased with higher content of DDM. On the other hand, the cement grouts incorporating DDM were rated as medium resistance to chloride penetration after 90 days of curing. The cement grout mixes were implemented in two construction applications: tile adhesive and plaster. The samples for both applications showed favourable behaviour with no observed cracks after 11 months of exposure to harsh environmental conditions. The promising results of this study would contribute towards reducing the environmental impacts of dam dredged materials and preserving natural resources, leading to sustainable and economic benefits to the UAE.

Keywords: Cement grouts, Compressive strength, Dam dredged materials (DDM), Rheology; Thixotropy.