Chloride Migration in Graphene Oxide Concrete

This paper presents experimental work on the chloride penetration resistance of concrete, incorporating 0%, 2% and 3% Graphene Oxide (GO) by weight of cement. Nine 100mm diameter and 200mm high concrete cylinders were cast in the Materials Laboratory at the University of Plymouth. The cylinders were cut into 50mm thick disks and rapid chloride migration tests were carried out. After the tests, the penetration depth of the disks were measured and chloride migration coefficients were determined. It was found that compared with the control samples, the addition of 2% and 3% GO reduced the migration coefficient of concrete by about 11% and 17% respectively at 28 days after casting. This suggests that the inclusion of GO into a cementitious mix does have a noticeable effect on the increase of chloride resistance and hence the longevity of concrete.

Compressive Strength of Uncured Concrete Cylinders Fully Wrapped with Post-Tensioned Metal Straps (PTMS).

During a national lock down and a curfew, most of the concrete projects are left without curing and therefore, the elements of the building need strengthening. An effective way in strengthening is using Post-Tensioned Metal Straps (PTMS) which is a relatively new method. Therefore, in this study, the effectiveness of using PTMS is tested in strengthening cylinder samples without curing. For this purpose, 15 cylinders are cast and 12 of them are left without curing for 28 days. Three samples are tested without any strengthening and are used as control samples. The rest are strengthened using 1, 2, 3, and full layers of PTMS. To compare the strength of the cylinders, 3 cylinders of the same batch are prepared and cured for 28 days. It is proved that the compressive strength of the cylinders can increase by 39%, 57%, 84% and 125% if the samples are strengthened using 1, 2, 3, and full layers of PTMS. It is also found that the failure becomes ductile as the number of layers is increased.

Performance of Light Weight Concrete with Coconut Shell and Fly Ash

The major factor that affects the housing delivery is high cost of materials for any conventional concrete. This has lead to find an alternative. An attempt has been made to find an alternative by using partial replacement of coarse aggregate by coconut shell aggregate and cement by fly ash. This report provides the information obtained from a literature search. And also provides laboratory experiments on Cement, Sand, Coarse aggregate and Coconut shell. This project is done using partial replacement of coarse aggregate by coconut shell aggregate and cement by fly ash.10 % of fly ash was kept constant as replacement for cement. And Coarse aggregate was replaced by 5%, 10%, 15%, and 20% of coconut shell aggregate.30 concrete cubes of 150x150x150 mm size were casted and 3 cubes were tested after 7 days of curing and 3 cubes were tested after 28 days of curing for each percentage.30 concrete Cylinders of 150x300 mm size were casted and 3 Cylinders were tested after 7 days of curing and 3 Cylinders were tested after 28 days of curing for each percentage.15 concrete Beams of 100X100X500 mm size were casted and 3 beams were tested after 28 days of curing for each percentage. Two models were done using ANSYS Software using the same failure loads from the experimental part. Keywords: Light weight concrete, coconut shell, Fly-ash, experimental.

Effective Strain of BFRP for Confined Heat-Damaged Concrete Cylinders

It is widely accepted that concrete columns confined with fiber-reinforced polymer (FRP) jackets exhibit significant increases in strength and ductility with reference to the unconfined case. Existing experimental studies have indicated that the hoop rupture strains measured in the FRP jackets are significantly lower than the material strain capacity determined by the flat coupon tensile tests. An FRP efficiency factor is then usually used to define the ratio of the average hoop rupture strain to the material strain capacity of the FRP jackets, which governs the lateral FRP confinement as well as the peak strength and ultimate strain of the FRP-confined concrete under axial compression. FRP jackets are also expected to be a promising solution to repair damaged RC columns after fire exposure. However, there is lacking research on the behavior of FRP-confined fire or heat-damaged concrete columns. In particular, the FRP efficiency factor of FRP-confined fire or heat-damaged concrete columns has not yet been established. The study presents the results of an experimental study aimed to investigate the effects of the historical high temperature and the layer of basalt FRP (BFRP) jackets on the efficiency factor of BFRP for the confined heat-damaged concrete cylinders. A sum of 51 standard concrete cylinders is prepared and tested under axial compression. The parameters varied between tests are the historical high temperature (200°C, 400°C, 600°C, or 800°C) that is used to produce the heat damage of concrete cylinders and the number of layers of BFRP jackets (2, 3, or 4). The test results have indicated that the efficiency factor of BFRP jackets increases with the historical high temperature but decreases slightly with the increase in the BFRP layers. A new temperature-dependent design equation for the BFRP efficiency factor of the confined heat-damaged concrete is proposed to consider the effects of the parameters mentioned above and can be used for practical design.

Analysis Of Use Sea Sand as A Fine Aggregate Replacement To Strong Press Concrete

Concrete is a composite building material made from a combination of aggregate and cement. The limitation of concrete material, in this case, is a fine aggregate (river sand). The utilization of sea sand as an alternative to fine aggregate in the manufacture of concrete is motivated by the availability of sea sand in nature in very large quantities. This study aims to determine the comparison and how much the compressive strength of concrete produced when using sea sand. The test was carried out when the specimens were 7, 14, and 28 days old with the specimens used in this study were concrete cylinders with a diameter of 15 cm and a height of 30 cm. The results showed that the use of sea sand as a substitute for fine aggregate showed an average compressive strength in 7 days of 18.86 MPa, an average compressive strength of 14 days of 25.52 MPa, an average compressive strength of 28 days of 29.00 MPa. Then for the average compressive strength value of the use of river sand in 7 days is 17.17 MPa, the average compressive strength of 14 days is 23.24 MPa, the average compressive strength of 28 days is 26.41 MPa.