Mohd Warid Hussin

Mix design and compressive strength of geopolymer concrete containing blended ash from agro-industrial wastes

Geopolymer concrete is a type of amorphous alumino-silicate cementitious material. Geopolymer can be polymerized by polycondensation reaction of geopolymeric precursor and alkali polysilicates. Compared to conventional cement concrete, the production of geopolymer concrete has a relative higher strength, excellent volume stability and better durability. This paper presents the mix design and compressive strength of geopolymer concrete manufactured from the blend of palm oil fuel ash (POFA) and pulverized fuel ash (PFA) as full replacement of cement with a combination of sodium silicate and sodium hydroxide solution used as alkaline liquid. The density and strength of the geopolymer concrete with various PFA: POFA ratios of 0:100, 30:70, 50:50 and 70:30 together with sodium silicate to sodium hydroxide solution by mass at 2.5 and 1.0, are investigated. The concentrations of alkaline solution used are 14 Molar and 8 Molar. Tests were carried out on 100x100x100 mm cube geopolymer concrete specimens. Specimens were cured at room temperature and heat curing at 60°C and 90°C for 24 hours, respectively. The effects of mass ratios of PFA: POFA, the alkaline solution to PFA: POFA, ratio and concentration of alkaline solution on fresh and hardened properties of concrete are examined. The results revealed that as PFA: POFA mass ratio increased the workability and compressive strength of geopolymer concrete are increased, the ratio and concentration of alkaline solution increased, the compressive strength of geopolymer concrete increases with regards to curing condition.

Application of Proteus mirabilis and Proteus vulgaris mixture to design self-healing concrete

AbstractThis study investigated two indigenous micro-organisms that can be isolated from soil. The isolated micro-organisms could precipitate calcium carbonate. These micro-organisms were applied to design self-healing concretes. Concrete is one of the most important materials which is used to build structures. Strength and durability of concrete is very important. Hence, a lot of research in this field is being conducted. Although a few reports can be found on the use of different micro-organism to design self-healing concretes, no research has been carried out to isolate suitable indigenous micro-organisms in Malaysia. In this study two strains of microorganisms were isolated from soil. Broken concrete was treated by a medium culture (MC) containing micro-organisms. Results of this study showed that, cracked concrete could be filled by calcium carbonate after treating by a MC containing micro-organisms. However, this treatment is not very effective on the strength of concrete. Results of this study can ...

Properties of aerated concrete containing various amount of palm oil fuel ash, water content and binder sand ratio

Palm oil fuel ash (POFA), a waste by-product from palm oil mills, is continuously increasing in amount. The POFA which is disposed off by the Malaysian palm oil mills into landfills could be causing environmental pollution and there is a need to study the possibility of recycling this waste product. A study was carried out on the behavior of this agro based aerated concrete based on the usage of different ash replacement levels, water content and binder sand ratio. Initially, mortar cubes (70.6mm) containing various replacement levels of ash were produced and tested for their compressive strengths. From these results the optimum strength from the related replacement level (20%) of POFA was used to investigate further the properties of the mortar cubes due to water content and binder sand ratio. Tests carried out for compressive strength followed the procedures in BS 1881: Part 116. The results show that the integration of 20% POFA in aerated concrete could be used as the production of a new green product suitable for non structural applications. Study also suggests that appropriate water content is necessary to promote aeration process that is responsible for the lightness of this material. However, integration of too much water content may promote rupture of pores and bleeding thus diminishes the strength of concrete. Sufficient cement is vital for the binding of the fine aggregates thus promoting concrete with good strength.

Compressive Strength of High Volume Slag Cement Concrete in High Temperature Curing

Recent consideration has been given to use of GGBFS as separate cementitious material mixed along with Portland cement in production of concrete. Problems are frequently encountered in producing good-quality concrete specially slag cement concrete in hot climates.Curing problems are exaggerated when concreting in hot weather, as a result of both higher concrete temperatures and increased rate of evaporation from the fresh mix. The disadvantage of GGBFS concretes is that they proved to be more sensitive to poor curing than OPC Therefore, special care must be taken when using this type of concrete, especially on site, where the working conditions and the application of curing are not as easy to control as in the laboratory concrete. The purpose of this paper is investigation and evaluation strength loss in slag cement concrete in poor curing situation. To carry out this aim, 72 cube specimens with three different proportion of slag are made and cured in two different conditions. And result of compressive tests compared together to determine susceptibility of GGBFS concrete in hot-dry condition.

Sustainable Pervious Concrete Incorporating Palm Oil Fuel Ash as Cement Replacement

Pervious concrete is one of the best materials used in sustainable drainage system to control the stormwater at source. The use of waste materials in concrete is able to reduce the negative impacts of concrete towards the environment. Therefore, this study presents the development of a sustainable pervious concrete by partially replacing cement with palm oil fuel ash (POFA) from palm oil industry. Properties, including void content, compressive and tensile strength as well as permeability were discussed. The results indicated that it is possible to produce sustainable pervious concrete by incorporating POFA. Furthermore, pervious concrete containing POFA showed higher water permeability and void content but lower compressive and tensile strength than control pervious concrete. However, the obtained compressive and tensile strength were within the acceptable range which is reported for strengths of pervious concrete.

Behavior of Palm Oil Fuel Ash and Metakaolin Ternary Blend Cement Mortar at Elevated Temperatures

This study examines the effect of a ternary blend of palm oil fuel ash (POFA) and metakaolin (MK) on the behavior of cement mortar exposed to elevated temperatures. The ternary blend was produced by combining 10% POFA and 10% MK by weight as a substitute to cement. Three additional samples which include plain portland cement (OPC), 20% MK binary and 20% POFA binary were also produced for comparison. Compressive strengths and ultrasonic pulse velocities of the mortar samples after heating to temperatures of 200, 400, 600, and 800°C for 2 h were assessed. Furthermore, X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy analysis were carried out to examine the microstructure of the samples. The results show that the compressive strength and microstructure of mortar exposed to elevated temperatures improved with the simultaneous use of POFA and MK compared to plain OPC mortar and when POFA or MK is singly used. The ternary blend of cement/POFA/MK can, therefore, be used as a fire resistant material.

Workability, Compressive Strength and Leachability of Coal Ash Concrete

One of the essential steps for planning solid waste management towards sustainable development is to reuse solid waste in the construction industry. Coal is one of the worlds most important sources of energy, fueling almost 40 % of electricity worldwide. Malaysia is commonly producing electricity through burning millions of tonnes of coal. This process generates around 8.5 Mt of coal ash, which comprised of 80 % Fly Ash (FA), and 20 % Bottom Ash (BA) as waste. The study aims to investigate the workability, compressive strength and leachability of concrete containing BA and FA as replacement of sand and cement. Cement was substituted with 20 % of FA by mass and fine aggregate was replaced with BA at 0, 20, 50, 75 and 100 % in the concrete mix. The results show that the percentage sum of SiO2, Al2O3 and Fe2O3 (the main chemical composition in coal ash) in FA and BA are about 78.82 % and 83.24 %. The leaching test showed that the heavy metal concentrations in leachates are much lower than recommended in the USEPA SW 846. Workability of concrete was reduced by increasing BA content as a sand replacement in the concrete mixture. After 91 d and 180 d curing periods, the compressive strength of both the experimental and control samples of concrete were roughly comparable. It can be concluded that BA and FA can be used as a replacement of sand and cement in normal concrete without any environmental problem.

Durability of Blended PFA and POFA Geopolymer Concrete

Ordinary Portland Cement (OPC) concrete is one of the most widely used construction materials globally, though its production in construction has negative environmental impact. About 0.9 ton of CO2 is emitted for every one (1) ton of cement produced. In order to reduce the amount of CO2 emission from cement industry, the utilization of supplementary cementitious materials such as pulverized fuel ash (PFA), blast-furnace slag and natural pozzolans is common and effective. Geopolymer is an inorganic binder material and can be produced by a geopolymeric reaction of alkali activating solution with silica and alumina rich source materials such as PFA and blast-furnace slag. In this study, the durability of concrete such as the resistance to sulfuric acid and sulfate solutions due to the effect of blended as of PFA and palm oil fuel ash (POFA), along with alkaline activators were investigated. Consequently, the optimum mix design of the blended ash geopolymer (BAG) concrete and OPC concrete specimens were prepared with water to cement ratio of 0.5 by mass as control. The micro structural analysis by X-ray diffraction (XRD) was done. BAG concrete showed better performance in 2% sulfuric acid and 5% sulfate solutions. From micro structural analysis, it was evident that BAG binder gel (N-A-SH) produced more durable material compared with C-S-H binder gel of OPC. The BAG concrete is strongly recommended to be used as an alternative to OPC concrete in addition to its environmental friendliness. Abundant PFA and POFA can be efficiently utilized to produce a high performance concrete.

Determining the causes of delay by using factor analysis in Tehran’s construction projects

Construction industry is one of the most profitable sectors in Iran’s economic. Delay is common problem in the construction projects in Iran. By considering all viewpoints of the parties, this research identified the most effective and severe causes of delay in construction projects in the Capital of Iran, Tehran. Questionnaires were distributed among respondents who are involved in the construction project in Tehran. The process of data analysis and discussions were conducted based on the two statistical techniques namely descriptive analysis (RII) and factor analysis. Using factor analysis, most critical factors of Tehran’s construction delay were recognized as: (1) lack of commitment; (2) inefficient site management; (3) poor site coordination; (4) Complexity in heritage and legislation; (5) Lack of estimation skills and skilled workers; (6) Lack of communication between parties; (7) Improper planning; and (8) Lack of clarity in contract. These results are anticipated to be important contributions to construction projects in Tehran in controlling the time overruns in construction contracts.