Effects of Eggshells Ash (ESA) on the Setting Time of Cement

Admixture properties of eggshells ash (ESA), with a focus on the setting time, were investigated. ESA was obtained by incinerating fowls’ eggshells to ash. The ash was sieved through 75μm sieve. The ash passing the 75 μm sieve was used in the investigation. Consistency test was carried out to establish the quantity of water required to constitute a standard cement paste of normal consistency in accordance to BS 12: 1991 [1]. Cement-eggshells ash (CESA) paste was constituted using 0%, 0.1%, 0.5%, 1%, 1.5%, 2.0% and 2.5% of ESA by weight of cement. Setting time test was conducted on the CESA paste in accordance to BS 12:1991 n[1]. Results show that the addition of ESA to the ordinary Portland cement (OPC) decreases the setting time of the cement. Conclusions drawn are that ESA is an accelerator; the higher the ESA content, the faster the rate of setting; all contents of the of the ESA employed in this investigation satisfy the setting time requirements of BS 12:1991 [1] for both the initial and final setting times. Thus, it is recommended that ESA can be used as an accelerator in concrete

Recycling of waste glass powder and tyre fiber in the development of eco-efficient concrete for high-performance structural application

Concrete suffers from several drawbacks due to the pollution associated with cement production, low tensile strength and low strain capacity that result in low resistance to cracks. Several attempts have been made to utilize waste materials for economical, sustainable construction and to improve concrete characteristics. This paper aims to investigate the effect of waste glass powder (WGP) as a partial replacement of cement and waste tyre fibre (WTF) as fibre reinforcement in the production of high performance concrete (HPC). ACI 211.1 was used to design a grade 50 HPC. At the first stage, WGP was introduced at a replacement level of 0 to 25 at a 5% interval by weight of OPC increment. Compressive strength at 3, 7, 28, 56, and 90 days of curing and slump flow was investigated, as well as establishing the optimum WGP content. WTF was then added to the optimal WGP-HPC in varying percentage addition of 0 to 2% at an increase of 0.4% by weight in the second stage. The compressive, splitting tensile, and flexural strengths at 3, 7, 28, 56, and 90 days were investigated. Slump flow was also investigated. It was discovered that the WGP is a suitable material for use as a pozzolana as it satisfied the minimum requirement given in ASTM C618. The compressive strength of HPC increased up to a 10% OPC replacement level by WGP before it starts declining. This signifies that the highest compressive strength was obtained at 10% WGP replacement level. It was also shown that adding the WTF decrease the slump flow and enhanced the compressive, splitting tensile and flexural strengths of WGP-HPC up to 1.2% and then dropped. Overall, an optimal HPC mix with 10% OPC replacement by GWP and 1.2% WTF addition outperforms all other mixes

Evaluation of the Influence of Ground Wastes Glass on Mechanical Properties of High Performance Concrete

The construction industry is largely reliant on the use of cement-based products. Every tonne of ordinary Portland cement (OPC) emits equivalent amount of CO2 into the atmosphere, contributing to increased raw material consumptions and environmental concerns. In this regard, the use of waste materials that can be blended with OPC as partial or full replacement to reduce the environmental impacts is strongly desirable. This research was experimentally carried out to evaluate the influence of ground waste glass (GWG) as a partial replacement of cement in high performance concrete (HPC). A grade 50 HPC was designed based on ACI 211.1-91. Various experiments were carried out to determine the mechanical properties of the HPC. Tests include specific gravity of constituent materials, sieve analysis of GWG and aggregates, slump flow of fresh HPC, compressive, splitting tensile and flexural strengths of hardened HPC were carried out. The chemical composition analysis of GWG was conducted using X-Ray Fluorescence (XRF) analytical method. HPC cubes, cylinders and beams were cast, cured and tested at curing ages of 3, 7, 28, 56 and 90 days using 0, 5, 10 15, 20 and 25 percentage replacement levels. The optimum compressive strength of 57.44 N/mm2 was obtained at 10% cement replacement after 28 days of curing age. The slump test result shows that the workability of the HPC decreased as the GWG content increases. Generally, the strengths of HPC reduced as the percentage of GWG replacement increased beyond 10% but increases with curing age. Therefore, 10% is the optimum replacement level of GWG for cement in HPC. &nbsp