EFFECTS OF VARYING WATER-CEMENT RATIOS ON DIFFERENT GRADES OF CONCRETE USING LOCALLY MATERIALS

This research focused on laboratory tests that was conducted using locally available 10mm washed all-in gravel, quarry dust with varying water cement ratio. The research was carried-out using 108 (150 x 150 x 150) mm standard cubes that were all tested from three designed concrete mixes. In the present study, the role of water-cement ratio in compressive strength of concrete was investigated. The mixed concrete samples with water-cement ratios of 0.3, 0.35 and 0.40 were experimented for 3, 7, 21 and 28 days of curing. The results of compressive strength experiment showed that due to increase in water-cement ratio from 0.3 to 0.40, the compressive strength improved from 22 N/mm2 to 24.33 N/mm2 for 1:1.5:3 design mix, the compressive strength improved from 22.88 N/mm2 to 24 N/mm2 for 1:2:1 design mix, while compressive strength improved from 24 N/mm2 to 25.3 N/mm2 for 1:1:2 design mix   respectively. The results for compressive strength experiments showed that the 0.4 water-cement ratio resulted in the optimum compressive strength for all three design mixes.     &nbsp

Grey and White Matter Magnetisation Transfer Ratio Measurements in the Lumbosacral Enlargement: A Pilot <i>In Vivo</i> Study at 3T

<div><p>Magnetisation transfer (MT) imaging of the central nervous system has provided further insight into the pathophysiology of neurological disease. However, the use of this method to study the lower spinal cord has been technically challenging, despite the important role of this region, not only for motor control of the lower limbs, but also for the neural control of lower urinary tract, sexual and bowel functions. In this study, the feasibility of obtaining reliable grey matter (GM) and white matter (WM) magnetisation transfer ratio (MTR) measurements within the lumbosacral enlargement (LSE) was investigated in ten healthy volunteers using a clinical 3T MRI system. The mean cross-sectional area of the LSE (LSE-CSA) and the mean GM area (LSE-GM-CSA) were first obtained by means of image segmentation and tissue-specific (i.e. WM and GM) MTR measurements within the LSE were subsequently obtained. The reproducibility of the segmentation method and MTR measurements was assessed from repeated measurements and their % coefficient of variation (%COV). Mean (± SD) LSE-CSA across 10 healthy subjects was 59.3 (± 8.4) mm² and LSE-GM-CSA was 17.0 (± 3.1) mm². The mean intra- and inter-rater % COV for measuring the LSE-CSA were 0.8% and 2.3%, respectively and for the LSE-GM-CSA were 3.8% and 5.4%, respectively. Mean (± SD) WM-MTR was 43.2 (± 4.4) and GM-MTR was 40.9 (± 4.3). The mean scan-rescan % COV for measuring WM-MTR was 4.6% and for GM-MTR was 3.8%. Using a paired t-test, a statistically significant difference was identified between WM-MTR and GM-MTR in the LSE (<i>p</i><0.0001). This pilot study has shown that it is possible to obtain reliable tissue-specific MTR measurements within the LSE using a clinical MR system at 3T. The MTR acquisition and analysis protocol presented in this study can be used in future investigations of intrinsic spinal cord diseases that affect the LSE.</p></div

Cross-sectional area (CSA) and magnetisation transfer ratio (MTR) measurements in the lumbosacral enlargement (LSE) of 10 healthy subjects.

<p>Abbreviations:- LSE-CSA: Lumbosacral enlargement cross-sectional area; LSE-GM-CSA: Lumbosacral enlargement grey matter cross-sectional area; WM-MTR: White matter magnetisation transfer ratio, GM-MTR: Grey matter magnetisation transfer ratio; DSC: Dice similarity coefficient.</p><p>Cross-sectional area (CSA) and magnetisation transfer ratio (MTR) measurements in the lumbosacral enlargement (LSE) of 10 healthy subjects.</p

Stacked plot diagram showing grey matter (GM) and white matter (WM) mean area fractions measured in a 15 mm section through the lumbosacral enlargement (LSE) in 10 healthy subjects.

<p>Stacked plot diagram showing grey matter (GM) and white matter (WM) mean area fractions measured in a 15 mm section through the lumbosacral enlargement (LSE) in 10 healthy subjects.</p

Prescription of the imaging volume between T11-L1 vertebral level to ensure coverage of the lumbosacral enlargement (LSE).

<p>Red arrow shows the position of the widest section of the LSE within the volume in this particular case.</p