Rita Irmawaty

Compressive Strength and Hydration Process of Self Compacting Concrete (SCC) mixed with Sea Water, Marine Sand and Portland Composite Cement

In order to eliminate the main problems of clean water shortage and fine aggregate in the low land areas and the distant islands, it is purpose to utilized the sea water, marine sand and Portland composite cement to produce the high performance Self-Compacting Concrete (SCC), where Portland composite cement containing of fly ash. The evaluation result on the mix design, workability (slump flow, segregation), mechanical properties (compressive strength-static modulus) and hydration process of SCC were discussed.

Flexural Capacity of Reinforced Concrete Beams Strengthened Using GFRP Sheet after Fatigue Loading for Sustainable Construction

Fiber reinforced polymer (FRP) has been applied not only for the simple structures but also for the advanced structures such as bridges or highway bridges for sustainable construction. In case of bridges or highway bridges, the structures experience not only static loadings but also fatigue loadings that may limited the serviceability of the bridge structures. In order to extend of the application of FRP on the such bridge structures to have a sustainable structures, the flexural capacity due to fatigue loading should be clarified. Glass composed FRP sheet namely Glass Fiber Reinforced Plastics (GFRP) is most commonly used due to its relatively lower cost compared to the other FRP materials. GFRP sheet is applied externally by bonding it on the concrete surface. Many studies have been done to investigate the flexural capacity of concrete beams strengthened using GFRP sheets. However, studies on the flexural capacity after fatigue loadings are still very rarely. This study presented the results of experimental investigation on the flexural capacity of the strengthened concrete beams after fatigue loadings. A series of concrete beams strengthened with GFRP sheet on extreme tension surface were prepared. Results indicated that after 800000 time of load cycle, the flexural capacity of beams specimens may decrease to only approximately 60%. The beam failed due to delaminating of GFRP sheet.

Effect of Sea Water Submersion on GFRP-S Bonding Capacity of Reinforced Concrete Beam

An experimental investigation on laboratory simulation of reinforced concrete beams submerged in sea water was carried out. The research aimed to analyze the beam flexural behavior cause by submersion effect in the marine environment and simulation pool. Flexural testing was conducted by using two point loading up to beams ruptured. Total 18 reinforced concrete beams of 10 cm x 12 cm x 60 cm in dimension with GFRP-S bonded on the bottom side. Nine beams were submerged in the marine environment and 9 beams were submerged in the simulation pool. Exposure period is 1, 3 and 6 months after 28 days cured in fresh water. The result indicate that the ultimate load and bonding capacity of beam specimens submersed in the marine environment were relatively lower than the specimens submersed in simulation pool. Based on this experimental study, submerging of specimens in simulation pool (Pp ) could be used to predict specimens submersed in marine (Ps) by using equation

A STUDY ON LONG-TERM PERFORMANCE OF CONCRETE OVER 50 MPa IN COMPRESSIVE STRENGTH

In recent years, the early deterioration of concrete structures has become a major problem. One factor contributing to the deterioration of infrastructure is corrosion of embedded steel in concrete, which is mainly caused by the ingress of aggressive agents (chloride ion and carbon dioxide, CO2). Concern is growing about the durability of concrete, which depends not only on the quality of the concrete, but also on environmental conditions.Despite the huge amount of data available from a variety of studies, however, only a little real information exists on the long-term performance of concrete. Based on the reason, this study undertook experimental test long-term performance of concrete over 50 MPa in compressive strength. Five level of strength were evaluated in order to measure micro-pore structure associated with the transport of aggressive agent to achieve a certain level of durability, evaluations were also conducted on the prestressed concrete (PC) sheet pile and PC beams exposed in the marine environment for long period, and durability design for Indonesian climate was recommended. The results indicate that micro-pore structure is directly affected by characteristics of materials (type and amount of mineral admixtures, and aggregatequality), W/B and curing time. For PC sheet pile, even high strength concrete, cover depth of 30 mm is not enough for long-term serviceability under marine splash environments, and it is predicted to be only 20year service life. Besides that, the use of GGBFS shows a significant reduction in the diffusion coefficient, which can provide a good barrier against chloride ingress and able to extend the service period of structures up to 65 years for 50 mmcover depth. Even though carbonation of the concrete did not cause corrosion of the reinforcement, however; it may have contributed to degradation of the cover concrete and indicating severe corrosion conditions for 35 years-old post-tensioned beams with 30 mm cover depth. Increasing in corrosion area of strands caused prestress losses up to 25% and the load bearing capacity dropped by 10%.In each case, it is clear that the quality of concrete and depth of cover to the reinforcement determines the time to corrosion activation. By considering Indonesian climate, a concrete cover of 70 mm with maximum w/c of 0.35 and minimum strength of 50 MPais recommendedif using Portland pozzolan cement (PPC) for a service life of 50 years.