Structural behaviour of ferrocement channels slabs for low cost housing

This paper presents a new pre cast U-shape ferrocement forms reinforced with various types of metallic and non-metallic mesh reinforcement. This research was designed to investigate the feasibility and effectiveness of employing various types of reinforcing meshes in the construction of structural slabs incorporating permanent U-shape ferrocement forms as a viable alternative for conventional reinforced concrete slabs. Fiber glass meshes reinforcement was used for durability and protection against corrosion of reinforcing steel. To accomplish this objective, an experimental program was conducted. The experimental program comprised casting and testing ten slabs having the total dimensions of 500x100x2500 mm incorporating 40 mm thick U-shape permanent ferrocement forms. Series A consists of two conventionally reinforced concrete slabs were cast and tested and used as control slab without fibers and with fibers, volume fraction, 2.05 % and 2.177 %. Series B comprises of two slabs reinforced with one and two layers of expanded steel mesh, volume fraction 2.09 and 2.42% respectively. Series C comprises two slabs reinforced with two and four layers of welded galvanized steel mesh, having volume fraction 2.05 and 2.189% respectively. Series D Consists of two slabs reinforced with one layer and two layers of fiber glass meshes, having volume fraction 2.107 and 2.277% respectively. Series E comprises two slabs reinforced with 2 layers expanded steel mesh and one layer expanded steel mesh, having volume fraction 1.357 and 2.750 % respectively. The test specimens were tested as simple slabs under four-line loadings condition on a span of 2300mm. The performance of the test slabs in terms of strength, stiffness, strains, cracking behavior, ductility, and energy absorption properties was investigated. The behavior of the developed slabs was compared to that of the control slabs. The experimental results showed that high ultimate and serviceability loads, better crack resistance control, high ductility, and good energy absorption properties could be achieved by using the proposed slabs and low cost compared with control specimen

Experimental and numerical study of the behavior of RC slabs with openings reinforced by metal mesh under impact loading

The main objective of the following work is to inspect the effect of reinforcing metal mesh on the behavior of slabs with openings under impact loadings. Based on an earlier numerical study by Shaheen et al. (2017), slabs with mid-side openings revealed the worst behavior regarding to deflection and cracked pattern when subjected to impact loading compared to other slabs with different locations of openings. Hence, the present work focuses specifically on this type of slabs and the variation in their behavior when reinforced by welded or expanded metal mesh. Seven specimens were prepared and tested in Faculty of Engineering, Menoufia University, Egypt. Moreover, a FE model for the slabs was built using Abaqus 6.14 and verified against test results. It was found that expanded metal mesh had a significant effect on reducing deflection due to impact load as well as controlling of cracks in contrast with welded metal mesh

Effect of aggregates with high gypsum content on the performance of concrete

Sulfates in fine aggregate are a major problem when it exists in excessive amount especially in the Middle East and Iraq. Most of sulfate salts in fine aggregate are composed of calcium, magnesium, potassium and sodium sulfates. Calcium sulfates is the most common salt present in fine aggregate. It is usually finding as gypsum. It is difficult to obtain the specific sulfates content in fine aggregate within standard specifications. This research was conducted to investigate the effect of adding different contents of gypsum to fine aggregate as a replacement by weight on some properties of two types of concrete {self-compacted concrete (SCC) and high strength concrete (HSC)}. In these work three bases mixes of each type of concrete are used: mixes with different contents of metakaolin, mixes with different contents of gypsum and mixes incorporating different contents of metakaolin and gypsum. This study is devoted to determine the allowable content of sulfates in fine aggregate. Three levels of gypsum were tested (0.5, 1, 1.5) % by weight of fine aggregate and three levels of metakaolin were tested (5, 10, 15) % by the weight of cement. The experimental program is devoted to produce concrete with different levels of metakaolin and gypsum and determine its mechanical properties such as compressive strength and splitting tensile strength. The results arrived from this work show that the optimum gypsum content was 1.5% by weight of fine aggregates for mixes of SCC which gives increases in compressive strength and tensile strength, and 1% gypsum for mixes of HSC, results showed also that the metakaolin improved the properties of the two types of concrete and increased the loss which caused by sulfates. The best mix ever in SCC is 1% gypsum with 5% metakaolin, and 1% gypsum with 10% metakaolin for HSC

Pre- and Post-Fire Strength Assessment of Ferrocement beams

The results of an experimental investigation on the behavior of ferrocement beams after exposed to fire are presented in this paper. Different types of steel meshes are used compared with conventional reinforcement. The experimental program comprised casting and testing of eighteen beams having the dimensions of 100mm×100mm×1000mm. Three beams were reinforced as a conventional reinforcement. Each control beam was reinforced with two steel bars of diameter 8 mm in tension, two steel bar of diameter 6mm in compression and stirrups of 6 mm diameter placed at 200 mm intervals. The ferrocement beams were reinforced with steel meshes without any stirrups. Two types of steel meshes were used to reinforce the ferrocement laminate. These types are: square welded wire fabric, and expanded wire mesh. Single layer, double layers and three layers of square welded wire mesh were employed. Single layer and double layers of expanded wire mesh were employed. The experimental program was classified into three groups. First group was tested without exposure to fire, the second group was tested after exposure to fire for six hours and the last group was tested after exposure to fire under loading. All specimens were tested under 4-points flexural loadings. The performance of the test beams in terms of strength, stiffness, cracking behavior and energy absorption was investigated. The results showed that high serviceability and ultimate loads, crack resistance control, and better deformation characteristics could be achieved by using the proposed ferrocement forms

Flexural Behavior of Lightweight Composite Ferrocement Plates

In recent years, producing lightweight structures is considered as one of the most important application of concrete. It has extensive applications in the architect and insulation work. The main objective of this study is to investigate the behavior and the performance of lightweight ferrocement (LWF) composite plates with lightweight materials as filler materials in flexural. Fifteen lightweight ferrocement (LWF) composite plates were investigated by conducting flexural tests. The main variables are (the thickness of plates, the type of filler materials, the type and number of layers of meshes). The behavior of lightweight ferrocement (LWF) composite plates is investigated by conducting flexural tests on fifteen simply supported rectangular plates under three lines loadings. Fifteen plates represented in twelve lightweight ferrocement (LWF) plates and three conventional reinforced concrete (RC) plates. The ferrocement plates were divided into three groups according to the thickness of plates 6cm, 8cm and 10cm. The structural performances of the LWF and RC plates are investigated in terms of crack load, load-deflection curves, stiffness, energy absorption capacity, ductility index, ultimate flexural load-to-weight ratio, load-strain curves, crack patterns, and the failure modes. The test results revealed remarkable enhancement in the flexural behavior and potential application of lightweight ferrocement (LWF) composite plates to produce lightweight structural elements as compared to that of the reinforced concrete (RC) plates, which lead towards the industrialization of building system and meets with innovation and expansible application of concrete construction technology results in better efficiency of developing of lightweight composite ferrocement plates

Structural Behavior of Composite Reinforced Ferrocement Plates

The results of an experimental investigation to examine the structural behavior of composite reinforced ferrocement concrete plates are presented in this paper. The precast permanent ferrocement forms are proposed as a viable alternative to the steel panels in some of its uses. The experimental program comprised casting and testing of eighteen reinforced ferrocement plates having the dimensions of 550mm width, 1100mm length and different thicknesses (60, 80,100) mm. Each control plate was reinforced with four steel bars of 6mm diameter at the bottom of the plate and six steel bars of 6mm diameter at the transverse direction. Two types of steel mesh were used to reinforce the ferrocement plates. These types are: galvanized welded wire mesh of size of opening 12.5x12.5mm, and (33 X 16.5mm) expanded metal wire mesh of diamond size 33x16.5mm. Single layer, double layers and three layers of each type of the steel mesh were employed. All specimens were tested under 3-lines flexural loadings. The flexural performances of the all tested plates in terms of strength, stiffness, cracking behavior, ductility and energy absorption properties were investigated. The results showed that high serviceability and ultimate loads, crack resistance control, and good energy absorption properties could be achieved by using the developed ferrocement plates.

MRI and pathology correlations in the medulla in SUDEP: A post-mortem study

Aims: Sudden unexpected death in epilepsy (SUDEP) likely arises as a result of autonomic dysfunction around the time of a seizure. In vivo MRI studies report volume reduction in the medulla and other brainstem autonomic regions. Our aim, in a pathology series, is to correlate regional quantitative features on 9.4T MRI with pathology measures in medullary regions. Methods: Forty‐seven medullae from 18 SUDEP, 18 nonepilepsy controls and 11 epilepsy controls were studied. In 16 cases, representing all three groups, ex vivo 9.4T MRI of the brainstem was carried out. Five regions of interest (ROI) were delineated, including the reticular formation zone (RtZ), and actual and relative volumes (RV), as well as T1, T2, T2* and magnetization transfer ratio (MTR) measurements were evaluated on MRI. On serial sections, actual and RV estimates using Cavalieri stereological method and immunolabelling indices for myelin basic protein, synaptophysin and Microtubule associated protein 2 (MAP2) were carried out in similar ROI. Results: Lower relative RtZ volumes in the rostral medulla but higher actual volumes in the caudal medulla were observed in SUDEP (P < 0.05). No differences between groups for T1, T2, T2* and MTR values in any region was seen but a positive correlation between T1 values and MAP2 labelling index in RtZ (P < 0.05). Significantly lower MAP2 LI were noted in the rostral medulla RtZ in epilepsy cases (P < 0.05). Conclusions: Rostro‐caudal alterations of medullary volume in SUDEP localize with regions containing respiratory regulatory nuclei. They may represent seizure‐related alterations, relevant to the pathophysiology of SUDEP

Intra-operative acquisition of sensorimotor fMRI during glioma resection: evaluation of feasibility and clinical applicability

Intra-operative fMRI has the potential to improve neurosurgical outcomes and we have previously shown that the task-related BOLD signal can be acquired under general anaesthesia. Our next goal was to acquire fMRI intra-operatively with the skull open. In 12 patients, we performed 24 acquisitions of a passive sensorimotor paradigm during the resection of their brain tumour. The fMRI data were evaluated by neuroradiologists, assessing its applicability for the provision of a clinical report on the location of sensorimotor activation to the neurosurgeon. 17/24 acquisitions were scored as useful. We conclude that intra-operative fMRI is feasible and produces clinically useful data

Acquisition of sensorimotor fMRI under general anaesthesia: Assessment of feasibility, the BOLD response and clinical utility

We evaluated whether task-related fMRI (functional magnetic resonance imaging) BOLD (blood oxygenation level dependent) activation could be acquired under conventional anaesthesia at a depth enabling neurosurgery in five patients with supratentorial gliomas. Within a 1.5 T MRI operating room immediately prior to neurosurgery, a passive finger flexion sensorimotor paradigm was performed on each hand with the patients awake, and then immediately after the induction and maintenance of combined sevoflurane and propofol general anaesthesia. The depth of surgical anaesthesia was measured and confirmed with an EEG-derived technique, the Bispectral Index (BIS). The magnitude of the task-related BOLD response and BOLD sensitivity under anaesthesia were determined. The fMRI data were assessed by three fMRI expert observers who rated each activation map for somatotopy and usefulness for radiological neurosurgical guidance. The mean magnitudes of the task-related BOLD response under a BIS measured depth of surgical general anaesthesia were 25% (tumour affected hemisphere) and 22% (tumour free hemisphere) of the respective awake values. BOLD sensitivity under anaesthesia ranged from 7% to 83% compared to the awake state. Despite these reductions, somatotopic BOLD activation was observed in the sensorimotor cortex in all ten data acquisitions surpassing statistical thresholds of at least p < 0.001uncorr. All ten fMRI activation datasets were scored to be useful for radiological neurosurgical guidance. Passive task-related sensorimotor fMRI acquired in neurosurgical patients under multi-pharmacological general anaesthesia is reproducible and yields clinically useful activation maps. These results demonstrate the feasibility of the technique and its potential value if applied intra-operatively. Additionally these methods may enable fMRI investigations in patients unable to perform or lie still for awake paradigms, such as young children, claustrophobic patients and those with movement disorders