Nasir Shafiq

Effects of initial curing condition on the fluid transport properties in OPC and fly ash blended cement concrete

Abstract This paper presents an experimental study of the influence of two initial curing conditions, wet (fog room) and dry (65% RH and 20 °C), on the transport properties of fluid in normal concrete (100% OPC) and blended cement concrete (OPC/FA). After 28 days initial curing, concrete samples were dried at different relative humidities at 20 °C for about 12 weeks when the equilibrium moisture condition was achieved. Transport properties that include oxygen permeability, water permeability and oxygen diffusion were measured at the equilibrium condition of the samples, and total porosity and degree of saturation were also determined. The initial curing condition has significant effects on the transport properties; in particular the most prominent effects were observed on fly ash blended cement concrete, which performed extremely well when initially cured in wet conditions.

Effects of Different Mineral Admixtures on the Properties of Fresh Concrete

This paper presents a review of the properties of fresh concrete including workability, heat of hydration, setting time, bleeding, and reactivity by using mineral admixtures fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), metakaolin (MK), and rice husk ash (RHA). Comparison of normal and high-strength concrete in which cement has been partially supplemented by mineral admixture has been considered. It has been concluded that mineral admixtures may be categorized into two groups: chemically active mineral admixtures and microfiller mineral admixtures. Chemically active mineral admixtures decrease workability and setting time of concrete but increase the heat of hydration and reactivity. On the other hand, microfiller mineral admixtures increase workability and setting time of concrete but decrease the heat of hydration and reactivity. In general, small particle size and higher specific surface area of mineral admixture are favourable to produce highly dense and impermeable concrete; however, they cause low workability and demand more water which may be offset by adding effective superplasticizer.

Comparison of engineering and durability properties of fly ash blended cement concrete made in UK and Malaysia

Abstract Annual global production of fly ash is ∼6 × 108 ton out of which only 20 to 25% is utilised in the construction industry. Largely it is used as a partial replacement of cement for producing concrete. Properties of such concrete depend on the chemical composition of fly ash, source and method of burning of coal in power stations, etc. The present paper presents a comparative study on the properties on concrete containing fly ash obtained from two different sources, Drax Power Station, UK and Manjung Power Station, Malaysia. Fly ash obtained from Malaysia contained 11˙47%CaO and its particles were coarser than the fly ash obtained from Drax, UK, which contained less calcium oxide (2˙55%). Malaysian fly ash concrete required more water to achieve the targeted slump of 55 ± 5 mm of fresh concrete, such concrete showed 4 to 7% high porosity and 27 to 36% low compressive strength as compared with the porosity and compressive strength of the concrete made with Drax, UK fly ash.

Effect of silica fume on the fresh and hardened properties of fly ash-based self-compacting geopolymer concrete

The effect of silica fume on the fresh and hardened properties of fly ash-based self-compacting geopolymer concrete (SCGC) was investigated in this paper. The work focused on the concrete mixes with a fixed water-to-geopolymer solid (W/Gs) ratio of 0.33 by mass and a constant total binder content of 400 kg/m3. The mass fractions of silica fume that replaced fly ash in this research were 0wt%, 5wt%, 10wt%, and 15wt%. The workability-related fresh properties of SCGC were assessed through slump flow, V-funnel, and L-box test methods. Hardened concrete tests were limited to compressive, splitting tensile and flexural strengths, all of which were measured at the age of 1, 7, and 28 d after 48-h oven curing. The results indicate that the addition of silica fume as a partial replacement of fly ash results in the loss of workability; nevertheless, the mechanical properties of hardened SCGC are significantly improved by incorporating silica fume, especially up to 10wt%. Applying this percentage of silica fume results in 4.3% reduction in the slump flow; however, it increases the compressive strength by 6.9%, tensile strength by 12.8% and flexural strength by 11.5%.

Carbon footprint assessment of a typical low rise office building in Malaysia using building information modelling (BIM)

Concrete and steel are considered the main structural building materials in todays construction. A fair amount of carbon footprint known as embodied carbon footprint is released during their extraction to ultimate utilisation in construction activities. However, quantification and evaluation of the embodied carbon footprint from structural materials of various grades was lacking. This study aimed to evaluate the variation in embodied carbon footprint potential when various classes/grades of concrete and steel in six different combinations were adopted during the design and planning phase using life-cycle analysis (LCA). Building information modelling (BIM) was utilised to virtually construct a two-storey conventional office building, and embodied carbon footprints for each of the six models were quantified. The study highlighted that up to 31% of embodied carbon footprint was avoided from the building. Model M1 (G25XS280) yielded the highest whereas model M4 (G35XS460) was the lowest in contribution. The...

Effect of Chopped Basalt Fibers on the Mechanical Properties and Microstructure of High Performance Fiber Reinforced Concrete

This paper presents the mechanical properties and the microstructure of the high performance fiber reinforced concrete (HPFRC) containing up to 3% volume fraction of chopped Basalt fibers. Three types of the concrete were prepared, out of which, the first type was prepared by utilizing 100% cement content. The other two types of the concrete were prepared by replacing 10% cement content with silica fume and the locally produced metakaolin. Using each concrete type, four mixes were prepared in which Basalt fibers were added in the range of 0–3%; that is, total twelve mixes of the HPFRC concrete were prepared. From each of the twelve concrete mixes, total twelve specimens were cast to determine the mechanical properties of the HPFRC including compressive strength (cube and cylinder), splitting tensile strength, and the flexural strength. In this way, a total of 108 specimens were cast and tested in this study. Test results showed that the addition of the Basalt fibers significantly increased the tensile splitting strength and the flexural strength of the HPFRC, while there was slight improvement in the compressive strength with the addition of Basalt fibers. The microstructure of HPFRC was examined to determine the interfacial transition zone (ITZ) between the aggregates and the paste by using field emission scanning electron microscope (FESEM), which showed the improvement of the ITZ due to the addition of the Basalt fibers.

Strength development of high-strength ductile concrete incorporating Metakaolin and PVA fibers.

The mechanical properties of high-strength ductile concrete (HSDC) have been investigated using Metakaolin (MK) as the cement replacing material and PVA fibers. Total twenty-seven (27) mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

Challenges for Implementation of Building Information Modeling (BIM) in Malaysian Construction Industry

The construction industry of Malaysia is very dynamic in nature and the adoption of new technological advancements and construction methods has been a prime concerns for its key players and stakeholders. However, the adoption of BIM in such a dynamic industry is observed to be limited and its implementation has not been as successful as it should have been. The study focuses on the identification and prioritization the factors challenging the implementation of BIM in Malaysian construction industry. The data has been administrated through designed questionnaire by identifying the factors / barriers, by literature review, for implementation of BIM in construction industry. The prioritization of such factors is expected to help the major stake holders to address the issues according to their priority which will save lot of previous time and financial with smooth implementation of BIM in Architecture, Engineering and Construction (AEC) industry in future project.

Microwave Incinerated Rice Husk Ash (MIRHA) and Used Engine Oil (UEO): Towards Sustainable Concrete Production

Rice is a primary source of food for billions of people and covers 1% of the earth’s surface. On average 20% of the rice paddy is husk, giving an annual total production of 120 million tones. Nowadays, there are two common methods used to dispose the rice husk which is either it is being dump or burnt. Rice husk ash (RHA) which is produced by burning paddy husk led to the issue of ozone layer depletion. It also causes damage to the land and the surrounding area where it is being dumped. Previous studies have pointed out that RHA produced contains more than 80% pure silica and if properly prepared, it is in an active form which behaves very much like cement. Same goes with used engine oil (UEO). Many people are aware that UEO shouldn’t be dumped, but recycled. It is incredibly toxic stuff and a gallon can contaminate one million gallons of water. Pouring it on land doesn’t reduce the risk either as it can seep down into the water table.The objective of this research is to obtain an optimum percentage of inclusion of microwave incinerated rice husk ash (MIRHA) as a cement replacement and UEO in order to produce a better concrete in terms of compressive strength compared to normal OPC concrete. The test results showed MIRHA concrete performed better than normal OPC concrete and the incorporation of UEO and MIRHA in concrete showed the compressive strength give better performance.

Effect of crumb rubber and nano silica on the fatigue performance of roller compacted concrete pavement

Abstract Roller compacted concrete (RCC) pavement is subjected to continues traffic loading from vehicular activities which can results to fatigue cracking. Fatigue is one of the commonest defects affecting pavement which affect the cost of maintenance, and shortens pavement design life. To carter for these factors, higher deformation resistant pavements with longer design life need to be designed. Therefore, in this study, crumb rubber was used as a partial replacement to fine aggregate in RCC pavement to improve its fatigue life. Five mixtures were considered; one control mixture, two mixtures with fine aggregate replaced using crumb rubber at 10 and 20% by volume; one mixture containing 20% crumb rubber as partial replacement to fine aggregate 1% nano silica added by weight of cementitious materials. Lastly, one high volumefly ash (HVFA) RCC pavement mixture where 50% cement was replaced with fly ash, and 20% fine aggregate replaced with crumb rubber. The results showed that both crumb rubber and nano silica increases the bending resistance and fatigue life of RCC pavement. While HVFA decreases both flexural strength and fatigue performance of RCC pavement. The double logarithmic-equation can best be used to determine the stress level–number of cycles (S–N) fatigue behavior and relation for RCC pavement mixtures.