Biography:3 Abdelhamed Ganaw is a lecturer at Alkhums University, Alkhums, Libya. He received his 4BSc and MSc in civil Engineering from Tripoli University, Libya and his PhD from 5University of Bradford, UK. His research interest includes high workability mortars using 6 super-plasticisers and fly ash and their effect on the production of preplaced aggregate 7 concrete, and concreting in hot environment. 8Ashraf F. Ashour is a Reader at the University of Bradford, UK. He received his BSc and 9MSc from Mansoura University, Egypt, and his PhD from the University of Cambridge, UK. 10His research interests include shear, plasticity, repair, strengthening and optimization of 11 reinforced concrete structures, fibre reinforced polymer composites, sustainable construction 12 and concrete technology. 13 Abstract 14The principal aim of this paper is to investigate the effect of sand grading, surface 15 morphology and content on the rheological properties, i.e., yield stress and plastic viscosity 16 of fresh mortar. Mortars were produced from four different types of sand, at two volumetric 17 cement-sand ratios of 1/0.9 and 1/0.6. Each blend was prepared with five water-cement ratios 18 of 0.60, 0.55, 0.50, 0.45 and 0.40. The rheometer, Viskomat NT, was used to determine yield 19 2 stress and plastic viscosity parameters of each cement paste and mortar. Test results show 20 that the relative yield stress and plastic viscosity of mortar to cement paste is inversely 21proportional to the excess paste thickness up to low values below which the surface texture of 22 sand particles becomes significant. 23 Introduction 24High flowability of fresh concrete is needed in modern concrete technology, such as in self-25 compacting concrete where no compaction is employed upon cast works and in pre-placed 26 aggregate concrete where mortar must develop high flowability filling the voids between the 27 coarse aggregate compacted mass without any vibration (Warner, 2004; Abdelgader, 1999). 28 Erdogan et al. (2008) reported that, although the flow characteristics of fresh concrete are 29 usually identified by its workability properties, it still lacks an accurate quantitative basis. 30Hence, rheology, that is the science of the deformation and flow of matter in the form of 31 relationships between stresses, strains and time, has been recently introduced to tackle this 32 problem. Tattersall (1991) reported that, for full understanding of material flowability 33 characteristics, both yield stress and viscosity are important parameters to be identified as 34 some materials may have the same yield stress but different viscosity or vice versa. 35Few investigations were conducted so far under the study of the effects of physical properties 36 of sand on mortar rheology (Banfill, 1994; Westerholm et al., 2008; Donza et al., 2002; Hu, 37 2005; Cortes et al., 2008). Banfill (1994) and Westerholm et al. (2008) concluded that an 38 increase of sand fineness increases both yield stress and plastic viscosity of mortar because of 39 both the ...
This paper investigates the effect of cement based grout rheology on the injection process through coarse aggregate for producing preplaced aggregate concrete (PAC). Four different sands were used in the grout production at different watercement ratios and cement-sand ratios. Superplasticiers (SP) and pulverised fuel ash (Pfa) were also employed in the grout production. Coarse aggregate of known weight was compacted into 150mm cubic forms, and then the grout was injected through a plastic pipe under self weight into the stone skeleton. It has been found that thereare threshold values of the rheological parameters beyond which full injection is not possible. In particular, all grout mixes with and without additives and admixtures exhibited the same yield stress threshold value for full injection, whereas the threshold values for other rheological properties including the grout plastic viscosity, flow time and speed were different according to the materials added to the mix.
It is well known to all of us that water plastic bottles waste has become a major problem to the environment. At the same time, incorporating the fibres in concrete like polypropylene is advantageous as they improve its properties. Nowadays self compacting concrete (SCC) has become very common in casting concrete due to its high flow properties and attained the required strength. The aim of this research is to study the effect of addition of shredded waste water plastic bottles to the constituents of SCC and comparing the results with those resulted from employing polypropylene fibre available in the market to the mix. In the study, SCC was produced at constant water content of 0.4 with the addition of constant super-plasticizer of 2% of cement weight, four fibre contents of 0.05, 0.075, 0.1 and 0.125 of the cement weight were employed to the mix, and then fresh and hardened properties of concrete were measured. From the results obtained, it was clearly observed that fresh and hardened properties of SCC can be obtained by using fibres produced from recycled water plastic bottles, and that off course will help in minimizing the pollution of environment.
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