Physical performance and durability evaluation of rubberized concrete

The main objective of this research is to develop rubberized concrete with achievable structural strength using simple mix design. Simple mix design is a description by using the crumb rubber, used as in condition just received from the plant without any washing or pre-treating procedure. Then, three types of durability test were conducted namely, 1) Chloride ion diffusion test, 2) Abrasion wear resistance test, and 3) Freezing and thawing test. Up-to-date, many successful achievements were reported by researchers around the world. However, in Asian cases, very rare information on the use of wasted as a mixture component is gathered. By conducting this study, it could provide useful and valuable knowledge for construction technology especially for Asian industry. This dissertation consists mainly of the seven chapters. In Chapter 1, the background, problem statement, significance, research contribution and novelty of this study are listed out. In Chapter 2, research review on previous researchers work on the application of waste tire rubber in mortar/concrete and durability are described. Several important properties related to this study were viewed and discussed. High reduction in strength properties was observed by previous researchers and many suggestions were proposed either by washing the rubber or the use of suitable treatment on the rubber surface in order to enhance the bonding of the matrix. However, in my research, by using conventional mixing method, it was proposed that to use the rubber without any treatment (use directly as received) with maximum 20% sand replacement in volume is a method to use crumb rubber effectively. As a result, each rubberized mixture showed an acceptable structural strength value. In Chapter 3, three step-by-step stages of mix design were conducted and discussed. The first stage was the preliminary study to determine the suitable waste tire rubber size and percentage replacement that can be used in rubberized mortar. Three rubber size group were received from the industry plant which where combination of 1mm-3mm, combination of 0.71mm-1.7mm and 0.425mm. Size of 1mm – 3mm with 10% of sand replacement was chosen in terms of acceptable fresh and hardened mortar properties. In second stage, suitable water-to-cement ratio (w/c) and required additional binder was determined before proceeding to concrete mix. Results shows that w/c = 0.35 gave reliable mortar physical properties. Finally, rubberized concrete with w/c =0.35 was carried out and specimens were prepared for mechanical test and durability test. Along these three stages, air content was carefully studied and controlled. In Chapter 4, experimental work and discussion on chloride ion diffusion in rubberized concrete tested by migration test and by immersion in salt water was described. Effective diffusion coefficient, De test was conducted according to JSCE-G571-2003. Meanwhile, immersion test in salt water was conducted according to JSCE-G572-2003. Additional concrete specimen with w/c = 0.50 was prepared to study the effectiveness of CR in high w/c in comparison with w/c = 0.35. Results showed that chloride transport characteristics were improved by increasing the amount of CR due to the fact that CR has the ability to repel water. Meanwhile, rubberized concrete with w/c = 0.35 gave better resistance against chloride ion compared to w/c = 0.50. In Chapter 5, discussion on the effectiveness of crumb rubber to improve wear resistance tested by surface abrasion test was described. An experimental study on abrasion wear resistance was conducted on mortar (w/c = 0.35, 0.30 and 0.25) and concrete (w/c = 0.35) specimen containing CR with and without silica fume. From test results, it was clearly seen that 10% crumb rubber addition as sand replacement provide good resistance against abrasion. Meanwhile, compressive strength was the most important factor affecting the abrasion resistance, where abrasion resistance was increased with an increase in compressive strength. However, abrasion resistance was found to be slightly decreased when compressive strength exceeds 50N/mm2. In Chapter 6, the role of crumb rubber as air void under freezing and thawing was studied. Specimen was prepared in three groups; first group was the specimen without silica fume with air content ranging between 4% to 5%, second group was the specimen without silica fume with air content ranging between 0% to 1.5% and third group was the specimen with silica fume with air content ranging between 4% to 5%. These rubberized concrete were tested on freezing and thawing resistance to understand this behavior. The temperature for freezing and thawing was set to 15oC ±5oC for thawing temperature and -18oC ±5oC for freezing. This test was continued until 300 cycles according to ASTM C666. Results show that up to 300 freeze-thaw cycle, there was no minus effect observed for all specimen. In Chapter 7, conclusions are drawn based on Chapter 4 to Chapter 6 and recommendations for future works is presented

A review on seawater as concrete composites and its effects on the strength and durability

The world is facing a big challenge of balancing a growing population and demand with a natural environment that is increasingly under stress. The rapidly changing environmental conditions especially intensity and frequency of extreme weather it has now become very important to explore in green technology. Effective use of natural resources is pressing concern. Particularly, water resources for drinking are predicted to be in serious shortage in 2050 due to increase in population and rapid urbanization throughout the world. The beginning of the 21st century is straddled with enormous environmental problems of which water shortage is one of the most serious. It is a well-known fact that fresh water resources are continuously declining throughout the world and according to a report by the United Nations, water will be very short in future. It is expected that 5bn people will be short of drinking water in 2050 [1]. In another report published by OECD, it is stated that a number of people living in river basins will be under severe water stress which is expected to be double in 2050 .

Preliminary Experimental Work on Concrete-Fly Ash Compressive Strength Blended with Seawater as Mixing Water

Fly ash is widely used in the construction sector, but application with seawater has not fully utilised. Seawater is utilised in construction to minimise the scarcity of drinking water. The concrete was strengthened by the utilisation of fly ash. Seawater replacing 100 percent tapwater as mixing water.  Meanwhile, fly ash was substituted with ordinary Portland cement at 10, 20, 30, and 40 percent. To achive the objective, the 100 mm x 100 mm x 100 mm cube size with 0.33 water-cementitious ratio were prepared. All series of mixture were casted  and cured in water for 7 and 28 days. The fly ash blended with seawater in concrete were investigate through its compressive strength. In addition, scanning electron miscroscope were carried out to capture surface image of the specimen. The experimental work result shows, with the existence of fly ash in concrete mixture, it decrease workability, density and compressive strength. Though the decreasing pattern was seen in every series, the structural strength was still deemed adequate

Preliminary Experimental Work on Concrete-Fly Ash Compressive Strength Blended with Seawater as Mixing Water

Fly ash is widely used in the construction sector, but application with seawater has not fully utilised. Seawater is utilised in construction to minimise the scarcity of drinking water. The concrete was strengthened by the utilisation of fly ash. Seawater replacing 100 percent tapwater as mixing water.  Meanwhile, fly ash was substituted with ordinary Portland cement at 10, 20, 30, and 40 percent. To achive the objective, the 100 mm x 100 mm x 100 mm cube size with 0.33 water-cementitious ratio were prepared. All series of mixture were casted  and cured in water for 7 and 28 days. The fly ash blended with seawater in concrete were investigate through its compressive strength. In addition, scanning electron miscroscope were carried out to capture surface image of the specimen. The experimental work result shows, with the existence of fly ash in concrete mixture, it decrease workability, density and compressive strength. Though the decreasing pattern was seen in every series, the structural strength was still deemed adequate

A Systematic Literature Review on the Effect of Seawater as A Promising Material on the Physical and Mechanical Performance of Concrete

Concrete is made from freshwater, cement, and aggregate and the only material shared with mankind, flora, and fauna is freshwater. One of the most concerning problems the world has been facing over the last few decades is the rising demand for freshwater due to the increasing global population and depleting source of freshwater by 2050. In Malaysia, the population is expected to rise from 32 million people in 2020 to 40.50 million people in 2050, which would correspondingly increase the demand for domestic houses, industrial areas, and other building construction as well as increase the overall usage of freshwater. The utilisation of seawater has been applied in constructing buildings and infrastructures since the time of the Roman Empire and the structures still survive for more than 2000 years against chemical attacks and underwater wave force. Given that seawater is considered an alternative mixing agent in concrete production, research on seawater-based concrete has continued to gain interest from the scientific community and undergone swift development. Therefore, the aim of this study was to present a systematic literature review on the recent development of concrete with seawater as the mixing agent and its effect on the physical and mechanical performance of the concrete. A four-stage investigation criterion was conducted for the data collection from the Scopus database, which includes the search parameter, identification, screening, and writing. The screening of the literature retrieved 53 articles, which were then classified based on the physical and mechanical properties of the concrete. Based on the review, the use of seawater as a single mixing agent reduced the physical and mechanical performance of the concrete. However, the incorporation of seawater with special chemical admixture, mineral admixture, and reinforcement with certain treatment resulted in a higher performance of the concrete. Finally, the review highlighted the various potential studies that can be performed to investigate the utilisation of seawater in the construction industry while achieving a sustainable solution to preserve the environment

Workability and Compressive Strength of Seawater-Mixed Concrete Containing Rice Husk Ash as Supplementary Cementitious Material

The world is grappling with the challenge of rapidly growing water crises. The increasing population demands increased infrastructure which at present leads to the consumption of trillion gallons of water every year in construction industry. This research aims to check the suitability of seawater as an alternate to freshwater for mixing and curing of concrete. Rice husk ash is used as supplementary cementing material in order to enhance the capacity of matrix to sustain higher stress. Specimens were prepared with rice husk ash using fresh water and seawater. Half of the specimens were cured in seawater and remaining half with freshwater. The water-cement ratio in this study was kept constant equal to 0.39. Workability of concrete was determined for both fresh water and sea water mixes. Density and strength parameters were determined at the end of curing periods. The workability of concrete was found to decrease in seawater compared to freshwater mixes. With the addition of RHA it was found to decrease in both freshwater as well as in seawater. The density showed a declining path with the use of seawater and increasing amount of RHA. The specimens for determining compressive strength were tested at 7 and 28 days. The compressive strength results concluded that initially rate of gaining strength of seawater specimen was higher than its freshwater counterpart. The seawater specimen showed higher strength at 10% replacement of cement with rice husk ash at the end curing period. It can be concluded that seawater added with RHA is suitable alternative to fresh water in concrete

Experimental Study on Cement and Fine Aggregate Replacement with Coal Bottom Ash in Seawater-Mixed Concrete

An experimental study was carried out to study the properties of concrete made with seawater as total mixing water, ground coal bottom ash as binary cement and coal bottom ash as sand replacement. The first stage mixes were prepared with three percentages (0, 10, 20 and 30) of ground coal bottom ash as partial replacement of binder. The second stage mixes involved 10 percent of ground coal bottom ash with 25%, 50%, 75% and 100% of coal bottom ash replacing natural sand. Properties investigated were materials properties, binder chemical composition, concrete hardened density, compressive strength, and SEM.  Test on hardened density was conducted on 7 and 28 days. Ground coal bottom ash was identified as Class F, while coal bottom ash has low specific density and high-water absorption compared to natural sand. Concrete density and compressive strength decreased on use of coal bottom ash as fine aggregate. Compressive strength was seen to decrease as CBA percentage rose, with the maximum value being 44.4 MPa for combination of 10 percent ground coal bottom ash and 25 percent coal bottom ash. Series with 10% CBA (ground coal bottom ash) reduces by roughly 51% while maintaining a sufficient structural strength value. The findings of this investigation showed that it is possible to produce seawater-concrete, which incorporates coal ash in concrete

Experimental Study on Cement and Fine Aggregate Replacement with Coal Bottom Ash in Seawater-Mixed Concrete

An experimental study was carried out to study the properties of concrete made with seawater as total mixing water, ground coal bottom ash as binary cement and coal bottom ash as sand replacement. The first stage mixes were prepared with three percentages (0, 10, 20 and 30) of ground coal bottom ash as partial replacement of binder. The second stage mixes involved 10 percent of ground coal bottom ash with 25%, 50%, 75% and 100% of coal bottom ash replacing natural sand. Properties investigated were materials properties, binder chemical composition, concrete hardened density, compressive strength, and SEM.  Test on hardened density was conducted on 7 and 28 days. Ground coal bottom ash was identified as Class F, while coal bottom ash has low specific density and high-water absorption compared to natural sand. Concrete density and compressive strength decreased on use of coal bottom ash as fine aggregate. Compressive strength was seen to decrease as CBA percentage rose, with the maximum value being 44.4 MPa for combination of 10 percent ground coal bottom ash and 25 percent coal bottom ash. Series with 10% CBA (ground coal bottom ash) reduces by roughly 51% while maintaining a sufficient structural strength value. The findings of this investigation showed that it is possible to produce seawater-concrete, which incorporates coal ash in concrete

Performance of independent horizontal and inclined bars as shear reinforcement for reinforced concrete beams

This paper presents an experimental results of concrete beams reinforced with new shear reinforcement design of using independent horizontal and inclined bars. A total of six beams, measuring 200 mm width x 250 mm height x 2300 mm length were tested up to failure under four-point loading. The effectiveness of using independent horizontal and inclined bars to the shear carrying capacity of the beam was investigated. The independent horizontal and inclined bars with reinforcement ratios between 1.0% and 2.9% were provided in reinforced concrete beams. All the beams were cast with normal grade of concrete compressive strength between 30 to 35 MPa. The performance of the tested beams in terms of ultimate load, mid-span deflection and crack patterns were recorded and compared. The test results showed that beams reinforced with independent horizontal and inclined bars of 1.9% and 2.9% experienced higher shear load capacities than beams with conventional shear reinforcement system. It can be concluded that the use of independent horizontal and inclined bars as shear reinforcement gives good shear resistant for the beams. Furthermore, these types of shear reinforcement system are more flexible, simple which significantly reduced the congestion of vertical links within shear span zone

Comparative study on structural behaviour of bonded and unbonded post-tenseoned beam

In this study, a simple computer program are written using FOTRAN 90 to investigate the behavior of simply supported beam constructed with straight tendon which are subjected to three different load cases. Considering the same stresses applied, beam subjected to loading at one third span shows a less deflection than other load cases. Behavior due to the deflection of bonded tendon gave better performance than unbonded tendon. However, beams with larger span-to-depth ratio would require deviators in case of external prestressing to achieve the desired performance. Parabolic and trapezoidal tendon allows the prestressed beam to carry heavier loads because of the balancing effects of the vertical component of the prestressing deflected tendon. Hence it will required less prestressing force at the mid span compared with the force required in the straight tendon