Percentage Loss Of Strength Research Articles

Durability of concrete made with groundnut shell ash as cement replacement

Concrete was considered in time past to be very durable, however many structures continue to show signs of deterioration during the specified or traditionally expected service life. The process of deterioration is more often caused by environmental factors. These have continued to enhance further research on processes as well as effective preventive measures on how best the use of available materials continually to produce durable concrete. The objective of this research is to investigating durability of using concrete produced with groundnut shell ash as replacement for cement. Groundnut Shell ash (GSA) was used to replace cement in percentages of 5%, 10%, 15%, 20% and 25% respectively. Sulfuric acid was used to provide the acid environment required for the short time durability test which comprise of 0.0005 %Ammonia (NH3), 0.00001 %Arsenic (As), 0.0002 %Chloride (Cl), 0.0001 %Heavy metals (Pb), 0.0001 %Iron (Fe), 0.00002 %Nitrate (No3), 0.00015 %, Oxygen absorbed (O), 0.0025 %and Non-volatile residue. Concrete Cubes were cast for control and three (3) samples for each for various percentage of cement replacement with 7, 14, 21 and 28 days curing period, a Second batch samples were inserted into sulfuric acid for another 28 days to determine durability of concrete. The results shows a loss in weight of the concrete with increase in curing age while decreases with increase in the dosage of GSA. With treatment, the concrete cube has a lower percentage loss in strength and the lowest value of percentage loss in strength achieved at 10% GSA at 28 days curing in sulfuric acid with a value of 0.18%. The reduction in percentage loss in weight recorded in the treated samples shows that concrete produced with GSA are more durable when compare to natural concrete.

Strength and durability of concrete using Rice Husk ash as a partial replacement of cement

Concrete is having most significant part in construction. The concrete mixture is made with the suitable ingredients like cement, fine aggregates, coarse aggregates and water. By using these materials, now a days the cost of the project is rising, to reduce the construction cost the natural materials are used to increase the strength values. In the current research the rice husk ash is used as a substitute for the cement in M20 grade concrete. The rice husk is the by product which is obtained from agriculture. The specimens are casted to determine the compressive, split tensile & flexural strength and durability of concrete. In this study the rice husk ash is used as a replacement of Ordinary Portland Cement (OPC) with 0%, 5%, 10%, 15%, 20% and 25% for workability, strength and durability values. From the experimental results it was noted that the highest values of compressive, split tensile and flexural strength for 7 days, 14 days and 28 days curing are obtained at 15% rice husk ash proportion & the percentage loss of strength and percentage loss of weight increases with increasing the rice husk ash content from 0% to 25% in M20 grade concrete.

EFFECT OF CURING METHODS ON STRENGTH PROPERTIES OF SELF COMPACTING CONCRETE INCORPORATED WITH METAKAOLIN AS SUPPLEMENTARY CEMENTING MATERIAL

The manufacturing of Self Compacting Concrete needs both chemical and mineral admixtures. The method of curing plays a vital role on strength and setting characteristics of SCC. Hence, this paper presents the results of an investigation dealing with the effects of curing methods on the compressive strength of SCC incorporating Metakaolin as supplementary cementing material. The SCC was prepared using 53grade OPC with and without Metakaolin as SCM. The Grades of concretes made were Standard concretes of M50 and High strength concretes of M80 grades. The compressive strength of the concrete was determined at 7 and 28days. The Curing methods adopted were the conventional method of water pond as reference and the Wax based Liquid membrane curing compound for research. The superplasticiser based on a polycarboxylic ether polymer with long lateral chains, is used to reduce water cement ratio and to improve the flow ability and filling ability of SCC. The ratio of water to binder is maintained at 0.4. It is observed that a significant loss in strength for High strength concretes of M80, around 25%, at 28 days of Wax based liquid membrane curing to that of Water curing. There is no significant change in compressive strength for the standard concretes of M50 grade using only 53grade OPC at 7 days of membrane curing to that of Water curing, but there is a loss in strength of around 8% at 28 days of membrane curing to that of Water curing. The incorporation of Metakaolin in high strength concretes reduced the percentage loss in strength because of reduced porosity.

The effect of sunlight and drying methods on the strength of Ghanaian Real Wax printed fabrics

AbstractThe effect of sunlight and drying methods on the strength of Real Wax printed cotton fabrics produced in Ghana was determined. Warp and weft specimens were washed using the Standard Launder‐Ometer (Gyrowash 315). Each laundered or unlaundered specimen was aired or dried on a flat surface or on clothesline in the sun or shade for 42 h. The breaking strengths of controlled and treated specimens were determined using the tensile testing machine (Hounsfield H5K‐S) and the average percentage loss in strength calculated. The analysis of variance and least significant difference for the separation of means were used to test significant differences between the treatments. Whether dried or aired, sunlight caused more loss in strength than shade. Laundered specimens lost more strength in the sun or shade than those unlaundered. Specimens dried or aired on a flat surface in the sun or shade lost more strength than those on clothesline. There were significant differences (P ≤ 0.05) as a result of the different treatments in the warp direction. For the weft specimens, there was a significant difference between only the aired and washed specimens. Conclusions and future research directions are discussed.