Khairul Nizar Ismail

Mechanical and microstructural evaluations of lightweight aggregate geopolymer concrete before and after exposed to elevated temperatures

This paper presents the mechanical and microstructural characteristics of a lightweight aggregate geopolymer concrete (LWAGC) synthesized by the alkali-activation of a fly ash source (FA) before and after being exposed to elevated temperatures, ranging from 100 to 800 °C. The results show that the LWAGC unexposed to the elevated temperatures possesses a good strength-to-weight ratio compared with other LWAGCs available in the published literature. The unexposed LWAGC also shows an excellent strength development versus aging times, up to 365 days. For the exposed LWAGC to the elevated temperatures of 100 to 800 °C, the results illustrate that the concretes gain compressive strength after being exposed to elevated temperatures of 100, 200 and 300 °C. Afterward, the strength of the LWAGC started to deteriorate and decrease after being exposed to elevated temperatures of 400 °C, and up to 800 °C. Based on the mechanical strength results of the exposed LWAGCs to elevated temperatures of 100 °C to 800 °C, the relationship between the exposure temperature and the obtained residual compressive strength is statistically analyzed and achieved. In addition, the microstructure investigation of the unexposed LWAGC shows a good bonding between aggregate and mortar at the interface transition zone (ITZ). However, this bonding is subjected to deterioration as the LWAGC is exposed to elevated temperatures of 400, 600 and 800 °C by increasing the microcrack content and swelling of the unreacted silicates.

Effect of Solids-To-Liquids, Na2SiO3-To-NaOH and Curing Temperature on the Palm Oil Boiler Ash (Si + Ca) Geopolymerisation System

This paper investigates the effect of the solids-to-liquids (S/L) and Na2SiO3/NaOH ratios on the production of palm oil boiler ash (POBA) based geopolymer. Sodium silicate and sodium hydroxide (NaOH) solution were used as alkaline activator with a NaOH concentration of 14 M. The geopolymer samples were prepared with different S/L ratios (0.5, 1.0, 1.25, 1.5, and 1.75) and Na2SiO3/NaOH ratios (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0). The main evaluation techniques in this study were compressive strength, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The results showed that the maximum compressive strength (11.9 MPa) was obtained at a S/L ratio and Na2SiO3/NaOH ratio of 1.5 and 2.5 at seven days of testing.

Mechanical Properties of Artificial Lightweight Geopolymer Aggregate (ALGA) Concreteusing Volcano Mud with Various Sintering Temperature

The mechanical propertiesof artificial lightweight geopolymer aggregate (ALGA) using volcano mud in concrete have been investigated at various sintering temperature. The volcano mud was mixed with alkaline activator, formed into spherical pellets, then sintered in the furnace at temperature of 500°C, 600°C, 700°C, 800°C, 900°C, 950°C, and 1000 °C. The lightweight concrete with density below than 1800 kg/m3 can be achieved at sintering temperature ALGA of 950 °C. The optimum compressive strength of 30.1 MPa was achieved at 28 days of testing. The lower water absorption of ALGA concrete was produced with 5-8 % in range.

Compressive Strength of Concrete from Lightweight Bubbles Aggregate

Compressive strength of concrete is the major mechanical properties of concrete that need to be focused on. Poor compressive strength will lead to low susceptibility of concrete structure towards designated actions. Many researches have been conducted to enhance the compressive strength of concrete by incorporating new materials in the concrete mixture. The dependencies towards natural resources can be reduced. Therefore, this paper presents the results of an experimental study concerning the incorporation of artificial lightweight bubbles aggregate (LBA) into cementations mixture in order to produce comparable compressive strength but at a lower densities. Three concrete mixtures containing various percentages of LBA, (10% - 50% of LBA) and one mixture used normal aggregate (NA) were prepared and characterized. The compressive strength of LBA in concrete was identified to be ranged between 39 MPa and 54 MPa. Meanwhile, the densities vary between 2000 kg/m3 to 2300 kg/m3.

Physicochemical properties of pyrolitic carbon black from waste tyres

Waste tyres which are mainly generated from automotive industries have become a major environmental problem to the local authorities, the tyre industries and tyre dealer. When tyres are no longer usable due to worn-out, defect or service failure they are usually dumped in the landfill sites. Pyrolysis is a process of the thermal decomposition of waste tyres in the absence of air and the oxygen. Pyrolysis may be an environmentally friendly process to transforms used tyres into gas, oil, steel and carbon black waste. The rate of recovery is 45 wt % for fuel, 30 wt % for carbon black and 10 wt % for steel wires for each end-of-life tyres. In this paper, the potential use of pyrolised carbon black generated from pyrolysis process of waste tyres is investigated. From the physical analysis of this carbon black waste, it was observed that there is various refraction particles sizes from the sieve test and different morphologies gathered from SEM analysis. Moreover, X-Ray Fluorescence (XRF) and TGA/DTG analysis on the carbon black waste showed high content of inorganic additives such as Silica (Si), Calcium (Ca) and Iron (Fe) which contaminate the sample. The carbon black waste started to decompose at a lower temperature of 480°C to 680°C compared to standard black at 500°C to 740°C. The test results gathered in this paper will act as a base-line towards alternative material or to replace the commercial carbon black available in the market.

Effects of Fly Ash Addition on Compressive Strength and Flexural Strength of Foamed Cement Composites

In this study, the mixing of polystyrene (PS) beads and fly ash as a sand replacement material in foamed cement composites (FCC) has been investigated. Specifically, the mechanical properties such as compressive strength and flexural strength were measured. Different proportions of fly ash were added in cement composites to replace the sand proportion at 3 wt. %, 6 wt. %, 9 wt. % and 12 wt. % respectively. The water to cement ratio was fixed at 0.65 meanwhile ratios of PS beads used was 0.25 volume percent of samples as a foaming agent. All samples at different mixed were cured at 7 and 28 days respectively. Based on the results of compressive strength, it was found that the compressive strength was increased with the increasing addition of fly ash. Meanwhile, flexural strength was decreased with the increasing addition of fly ash up to 9 wt. %. The foamed cement composites with 12 wt. % of fly ash produced the highest strength of compressive strength meanwhile 3 wt. % of fly ash produced the highest strength of flexural strength.

Performance of steel wool fiber reinforced geopolymer concrete

In this paper, performance of geopolymer concrete was studied by mixing of Class F fly ash from Manjung power station, Lumut, Perak, Malaysia with alkaline activator which are combination of sodium hydroxide and sodium silicate. Steel wool fiber were added into the geopolymer concrete as reinforcement with different weight percentage vary from 0 % - 5 %. Chemical compositions of Malaysian fly ash was first analyzed by using X-ray fluorescence. All geopolymer concrete reinforced with steel wool fiber with different weight percentage were tested in terms of density, workability, and compression. Result shows Malaysian fly ash identified by using XRF was class F. Density of geopolymer concrete close to density of OPC which is approximately 2400 kg/m3 and the density was increase gradually with the additions of steel fiber. However, the inclusions of steel fibers also shows some reduction to the workability of geopolymer concrete. Besides, the compressive strength was increased with the increasing of fibers a...

Review on Different Types of Geopolymer Concrete Fibres

Ordinary Portland Cement (OPC) has been used over the than hundred years for material construction especially as a binder in production of concrete. However, there are a few disadvantages with the using of OPC that have been found especially in terms of properties and green house effect. This paper reviews the potential of an alternative binder material with no cement usage (cementless) called as “geopolymer”. The history of the development geopolymer will be described. Different types of base materials used in the formation of geopolymer will be explained in details. The influence of different types of fibres to the mechanical properties especially compressive strength and flexural strength were explained well.

Performances of Artificial Lightweight Geopolymer Aggregate (ALGA) in OPC Concrete

The non-availability of natural lightweight aggregate and demand are increasing in worldwide, thus new alternatives on producing artificial aggregate should be developed. This paper discussed on the mechanical properties of artificial lightweight geopolymer aggregate (ALGA) made from LUSI mud and alkaline activator in concrete. LUSI means Sidoarjo mud from Indonesia which erupted on 2006 with high volume and impacted an area of almost 770 hectare. The alkaline activator used was combination of sodium hydroxide and sodium silicate. The geopolymer paste formed need to be pelleted and sintered at 950 °C. The results showed that the compressive strength of OPC-ALGA concrete is 41.89 MPa at 28 days of testing with a density of 1760.1 kg/m3 which can be classified as lightweight concrete. The water absorption of ALGA concrete is 2.77%.

Strength, Density and Water Absoprtion of Palm Oil Boiler Ash (POBA) Geopolymer Brick/IBS Brick

Geopolymer or alkali-activated binder is produced by synthesizing aluminosilicate source materials with an alkaline activator solution. This study has been conducted to produce palm oil boiler ash (POBA) geopolymer brick/IBS brick by using geopolymerisation method. Mix design of geopolymer brick/IBS brick was produced using NaOH concentration, ratio of S/L, ratio Na2SiO3/NaOH and curing temperature of 14 M, 1.5, 2.5 and 80 °C. The ratio of POBA-to-sand for geopolymer brick/IBS brick for this study was 1:3. The properties of geopolymer brick/IBS brick were analyzed in term of compressive strength, water absorption and density at different aging period, which is 1st, 3rd, 7th, 28th and 60th days. The result showed that the geopolymer brick produced using POBA, showed an increment in strength with times where the maximum strength obtained was up to 16.1 MPa (60th days). The density of this brick was in the range 1615 kg/m3 to 1750 kg/m3 and can be classified into medium weight for non-loading brick according to ASTM C129 (2013). As for the water absorption, the range was 6.8% to 12.2%, which is less than limit (17%) of ASTM C90 (2013) specification. For geopolymer IBS brick, the maximum compressive strength at 60th days was 14.3 MPa. There are slightly different strength of geopolymer IBS brick, which is due to the existence of tongue and groove on the surface of IBS brick thus leads to lower strength. The geopolymer IBS brick was classified as medium weight brick according to ASTM C129 (2013) with density a in the range 1792 kg/m3 to 1894 kg/m3 and water absorption 8.7% to 14.5%.