The Effect of Microbes and Fly Ash to Improve Concrete Performance

This paper presents the application of�fly ash�combining with microbes in concrete to reduce cement content.�A class F fly ash as cement replacementwas applied with ratios of 20%, 30%, 40%, and 50% to reduce hydration heat. Microbes from bacterial consortium were applied to as the filler to increase concrete compressive strength. The concrete mix design from SNI 03�2834�2000 was applied for a compressive strength target of 30 MPa. The mechanical test was carried out consisting compressive and tensile test.�Concrete�workability�and the heat hydration measurement were performed for fresh concrete.�The results showed that the maximum strength of 45.10 MPa was obtained from specimens with 30% fly ash content.�Application of microbes associated with�fly ash content of 40% showed the maximum strength of 48.47 MPa.�It was found that the tensile strength also increased with the application of�fly ash�and microbes.�Hydration temperature of concrete decreased with the increase of�the ash�content.�This proves that the application of�fly ash�and microbes in concrete can reduce the cement as well as increasing the concrete performance.

Performance of Recycled Concrete Made from Railway Sleeper: Experimental Study

Concrete railway sleeper has been used in Indonesia since about 1990�s. It has more advantage that is less maintenance, stabile, good quality, shapeable, onsite raw material, and higher loading ability [9-10, 20 - 22]. But It is prone to damage such as cracking and breaking during construction, so it is often thrown away as a solid waste that can contaminate the land and reduce soil fertility. Therefore, it should be utilized in order to be more useful that is used as recycle aggregate. The concrete waste that is taken from broken concrete railway sleeper will be crush as an aggregate as raw material in the concrete to substitute part or all of the normal concrete. It is called recycled aggregate and concrete that is made from recycled aggregate is called recycled concrete. Base on the testing of raw material, the recycled aggregate can be met to the specification as ASTM [1], so it can be used for concrete raw material. Recycled concrete compressive strength result lower the normal concrete compressive strength in the same initial strength design. The strength value of recycled concrete is decrease about 1 � 17% for 25 MPa and 10 � 18% for 30 MPa. It is also happened to tensile strength of recycled concrete that decrease about 2 � 13 % for 25 MPa and 7 � 22 % for 30 MPa.

Flexural Behaviors of Precast Reinforced Concrete -EPSfoam-Steel Deck Hybrid Panel

This paper presented the flexural behavior of the newly developed hybrid panel which included the comparison of the ultimate load, load-deflection behavior, and failure modes. The experimental study was carried out on precast reinforced concrete-EPSfoam-steel deck hybrid panels (CES)� consist of three layers of material : concrete� layer is on the top, the steel deck is located on the bottom layer, and the EPS foam layer as the core. The dimensions of CES are 300 mm x 1200 mm with thickness of concrete layer and EPS foam as variables. The concrete thick were 30 mm and 40mm. The density of EPS foam was 12 kg/m3, 20 kg/m3, and 30 kg/m3. The static flexural test of CES was conducted in accordance with the ASTM C 393-00 standard for determination of flexural strength on concrete, the load was applied at third-point loading. This test was carried out with monotonic static load, deflection control using a loading frame with capacity of 10 kN. The results show that increase the thickness of the concrete layer from 30mm to 40mm with� EPSfoam density of 12 kg /m3, 20 kg/m3, and 30 kg/m3 achieved a maximum load increase of 33.51%; 46,13%; and 37.35%, respectively.

Comparison of California Bearing Ratio (CBR) Value Based on Cone Penetration Test (CPT) and Dynamic Cone Penetrometer (DCP)

In civil engineering, land is important because as a place for building infrastructure to be built, so that the building infrastructure on it is stable, adequate carrying capacity is needed. The amount of soil bearing capacity can be determined in several ways, including the California Bearing Ratio (CBR) Field Test, Cone Penetration Test (CPT) and Dynamic Cone Penetrometer (DCP). The CBR and DCP tests are often used to determine the level of surface soil density on road structures, while CPT is usually used to determine the hard soil layer on the building structure. However, in certain situations Sondir and DCP data are often used to predict the CBR value, because the test is quite practical and efficient compared to the CBR test. CBR testing requires heavy equipment which in most small-scale projects is not available. In this study, we compared the CBR value based on the data obtained from the Sondir and DCP tests. Data collection was carried out in Surakarta and its surroundings. Based on the test results, the CBR value generated from the DCP test tends to be smaller than that from the CPT test with a ratio of 0.62: 1. This study resulted in the relationship between CBR values from the results of the CPT and DCP tests shown in the following equation: CBR (DCP) % = 0.2552 CBR(CPT) + 2.6306 and CBR (DCP) % = 0.617 CBR(CPT).

Behavior of Normal Concrete Reinforced with Fiber

Concrete is a material with the ability to withstand a fairly high pressure, yet it has a low ability to withstand tension. To be utilized as a structure material, improvements need to be made to increase its tensile strength. Addition of fiber in the concrete mixture is recognized to be one among the existing methods to increase the tensile strength. Considering its high tensile strength, This study aimed to examine the compressive strength, the split tensile strength, the flexural and elastic modulus of the normal concrete with Menjalin fibers. The examination was conducted using a cylinder with the diameter of 15 cm and the height of 30 cm and a beam with the size of 15x15x60 cm. Fiber addition was 0.65% of the total concrete materials with various fiber lengths ranging from 2.5 cm, 5 cm, 7.5 cm to 10 cm. The experiment was made by the means of a concrete cylinder compressive test and a flexural test of unreinforced concrete blocks. Results of the study showed, at the age of 21 days, the highest average compressive strength value of 194.37 kg/cm2 and the split tensile strength of 30.43 kg/cm2 in the concrete with fiber of 5 cm long were obtained. The highest flexural modulus value of concrete occurred in the specimen with the fiber length of 7.5 cm (55.7 kg/cm2), while the highest elasticity of concrete occurred in the specimen with the fiber length of 5 cm (2.45x105 kg/cm2).

Comparison of Stress-Strain Relationship for Confined Concrete Using Two-Dimensional Fiber-Based Cross-Sectional Analysis

Stress-strain relationship is the main parameter to identify the strength, ductility and behavior of the structure. Various constitutive models were created in order to simplify the analytical approach of concrete behavior. In this paper, the behavior of reinforced concrete column is modeled using Attard and Setunge�s (1996) and Mander�s (1988) stress-strain constitutive model. The appropriate model for reinforced concrete column was determined based on the existing experimental data. Two-dimensional simulation of reinforced concrete column using fiber-based cross-sectional analysis in MATLAB is sighted. And the performance of the reinforced concrete column from the experimental data is compared with the analysis result from the simulation. There are two comparation methods used in this research. The first method is to compare the linear regression with the reference line. The smallest degree between the linear regression and the referrence line is expected. The second method is to compare the Root Mean Square Defiation (RMSD) value. The smallest RMSD value is expected to get the most suitable constitutive model compared to the experimental data. From the computational process, it was found that Mander�s Constitutive model is preferaed to be used in further analysis problem concerning reinforced concrete column

The axial capacity of a full height rectangular opening castellated steel beam with steel reinforcement stiffeners

The axial capacity of a full height rectangular opening castellated steel beam with steel reinforcement stiffeners is proven to prevent Vierendeel failure mechanism. The effect is an increase in flexural capacity of the structure. Diameter of the steel reinforcement stiffeners is revealed to have an effect on its strength in resisting axial forces occur in the structure. However, size of the diameter is limited to the strength maximum value of the steel flange section in withstanding the moment force. Using optimal design of the castellated steel structure, this research aimed to find out the increase value of the axial capacity. There were two models of steel structures employed in the study, IWF 200x100x5.5x8 and castellated beam 362x100x5.5x8, both were loaded with axial directions. Analyses were conducted using truss and pushover methods. Results of the study showed an increase in both flexural (36.81%) and axial (60.78%) capacities. The increase in the value of structure capacity mainly influenced by the stiffeners shortened the effective length of the structure.

Retrofitting of Reinforced Concrete Beams Using a Fiberglass Jacketing System

Building collapse that occurred mostly caused by structure failure in containment earthquake load. Factors that lead to the failure of the beam, among others is beam planning that does not calculate ductility or restraint, resulting decline of beams performance. One way to improve beam strength and ductility are to retrofit the beam by wrapping beams using fiberglass. Research aims to discover the increase amount of bending load capacity from concrete beam that has been retrofitted using jacketing fiberglass. Experimental testing was carried out on beam specimens with a cross section size of 150x200 mm and a length of 1400 mm. Three beam specimens were subjected to bending loads with a three point loading system, with different levels of damage, namely BL1 with collapse at level-1, BL2 at level-2, and BL0 at level-5 as a comparison. Then the BL1 and BL2 were retrofitted by being coated with 2 layers of fiberglass which were glued using epoxy resin. Beams BL-1 and BL-2 are then subjected to a bending test again until they reach level-5 collapse. The test results showed that retrofitted beams were able to increase flexural strength, BL-1 increased 115.15% from the original load and BL-2 increased 52.27% from the original load.

The Relation Tensile Strength And Flexibility Of Bamboo For Soil Stabilization

Bamboo is an abundant material and easily available in Indonesia. In addition to having high compressive strength and tensile strength as well as ease of obtaining and low prices, bamboo is a consideration and focus in developing in the world of construction today. In this study, bamboo is used for soil stabilization, where bamboo is used in the form of fibre. This research focuses on the strength properties of various types of bamboo. The focus is to investigate the relationship between the maximum tensile strength of bamboo and the flexibility of bamboo in soil stabilization. This is very important, because bamboo fibers used for soil stabilization rely on their tensile strength rather than their compressive strength. Thus, the optimum tensile strength and flexibility of bamboo must be of particular concern. From the results of the study of the tensile strength of two types of bamboo, namely Apus Bamboo and Java Bamboo, the Apus Bamboo results were found to have a higher tensile strength of 225.57 mpa with maximum flexibility of 19.99 mm and 43.76 mpa for tensile strength of Javanese Bamboo with a level of flexibility of 10.26 mm.

Utilization of Oil Palm Empty Fruit Bunch in Cement Bricks

Oil palm empty fruit bunch (EFB) is a biomass waste abundantly produced by the oil palm industry in Malaysia. To minimize the environmental impacts, it needs to be properly disposed of or being rapidly consumed as a raw material of another industry. This study investigated the feasibility of substituting EFB in cement bricks, which is in high demand by the construction industry. A total of 120 specimens having the cement-to-sand (c/s) ratios of 1:2.5 and 1:3 were produced in the laboratory. EFB fibre was used to replace 10% to 25% of sand in the mix by volume. The specimens were tested for the compressive strength, density and water absorption after 28 days of casting. For the mix of 1:2.5 c/s ratio, 25% EFB content reduced 22% of density, decreased 59% of compressive strength and increased 43% of water absorption capacity of normal cement brick. This was mainly attributed to the porous cellular structure of EFB fibre that created a large volume of voids in the mix. Based on the feasibility evaluation, EFB fibre can only replace up to 15% and 10% of sand in the mixes of 1:2.5 and 1:3 c/s ratios respectively.