-
Sustainable Concrete Containing Recycled Aggregates and Pozzolana in Sudan
Eltahir Elshiakh,
Salma Mahmoud
Issue:
Volume 4, Issue 2, December 2020
Pages:
33-38
Received:
17 July 2020
Accepted:
3 August 2020
Published:
13 August 2020
Abstract: Sustainable trails in the building industry called for preserving the natural resources through the production of green concrete. This is concrete where waste materials are used as at least one of its components, or its production does not lead to environmental destruction through the reduction, reuse or recycling techniques. Experimental results from a study on the potential usefulness of recycled coarse aggregates (RCA) blended with locally available natural Pozzolana are outlined in this paper. Eight concrete mix scenarios were considered: a standard mix with 100% natural coarse aggregates (NCA), 25% RCA, 50% RCA, 75%RCA, 100% RCA and no Pozzolana, 100% RCA and 10% Pozzolana, 100% RCA and 20% Pozzolana, 100% RCA and 30% Pozzolana. Slump test was conducted and the results were all within the specific limits. It was conversely realized that the workability decreased in the cases of replacing NCA by RCA with no Pozzolana while an increase was recognized when the Pozzolana was add in the different percentages with the best results achieved with 100% RCA and 20% Pozzolana. The compressive strength results were consistent for the different curing ages with the highest strength being acquired with the mix that contained 100%RCA and 10% Pozzolana. The results of the durability test revealed better values for the wave length speed value when the NCA was replaced by the RCA. Considering these outcomes, the optimum result was achieved in the case of 100%RCA and 10%Pozzolana. Thus, the experimental results offer good indication for a potential usefulness of RCA proposing a reasonable way for preserving virgin natural materials.
Abstract: Sustainable trails in the building industry called for preserving the natural resources through the production of green concrete. This is concrete where waste materials are used as at least one of its components, or its production does not lead to environmental destruction through the reduction, reuse or recycling techniques. Experimental results f...
Show More
-
A Review on Problems of the Public Building Maintenance Works with Special Reference to Nepal
Ram Chandra Dahal,
Khet Raj Dahal
Issue:
Volume 4, Issue 2, December 2020
Pages:
39-50
Received:
8 July 2020
Accepted:
4 August 2020
Published:
18 August 2020
Abstract: The study was conducted during the period from the month of March to April 2020. Published literatures such as thesis, paper, manuals, reports, and database were collected from different sources and studied thoroughly. The conclusions were drawn on the basis of the studied materials. The study found that the public buildings of any nation are too valuable assets and maintaining them at regular functional state is becoming challenging job for developing countries like Nepal. The most significant building maintenance problems are: plumbing and w/s, toilet, bathroom and sanitary, electrical problems, poor maintenance management and practices, peeling of paint, dampness, surface cracking, growth of fungi or small plants and decay or breaking of floor/tile. Decay, deterioration and failure of the fabric and finishing of a building due to negligence of maintenance have harmful effects on the contents and occupants. Causes of maintenance problems can be grouped as managerial, technical, building user related and natural causes. There are major causes such as design defects, inadequate contractor and construction supervision, use of low quality materials and workmanship, unavailability of qualified human resources and quality materials, poor maintenance management, insufficient maintenance fund but high and unexpected cost, age of building, natural disaster and earth settlement and so on. Lack of proper maintenance department, programs, plan and policy are the critical issues of improvement by public institutions. Patent and latent defects in buildings are serious issues and failure to address them would contribute to additional rectification cost, hamper the smooth operation of the building and reduce its service life. Buildings and facilities that are not properly maintained can cause discomfort and lead to accidents and injury to the users. The study would like to suggest that the handling of maintenance problems should be minimized by identifying the root causes and applying the effective and efficient maintenance management program. Precaution should be applied at design and construction stage ensuring quality construction and delivery with all building documents. Furthermore, each public institution should formulate maintenance objectives, apply suitable strategy, manage adequate resources, develop maintenance action plan, periodic review of performance and strategy at service stage.
Abstract: The study was conducted during the period from the month of March to April 2020. Published literatures such as thesis, paper, manuals, reports, and database were collected from different sources and studied thoroughly. The conclusions were drawn on the basis of the studied materials. The study found that the public buildings of any nation are too v...
Show More
-
A Review on Disaster Resilient Residential Structure with Special Reference to Nepal
Ranjana Pokharel,
Khet Raj Dahal
Issue:
Volume 4, Issue 2, December 2020
Pages:
51-60
Received:
22 July 2020
Accepted:
19 October 2020
Published:
23 October 2020
Abstract: Natural disasters are counterproductive to developing countries’ economic growth, as they may be accompanied by a reduction in the Gross Domestic Product (GDP), rise in imports, and deterioration in fiscal balances. The research was conducted during the period from September to December 2019. The main goal of this analysis was to find out the weakness of the construction of disaster-resilient residential in and around the world. The special focus is given to Nepal. Throughout this analysis, secondary literature received from various sources such as published reports, papers, thesis, database, and manuals were collected and the conclusion is drawn based on studied materials. It is noted that 21 major natural disasters in Southern African countries led to an overall worsening of the trade balance owing to an increase in import growth and, to a lesser extent, a reduction in export growth. Due to flooding in 2000, Mozambique lost over 10% of its total viable land, as well as the crops in the field, and about 40,000 head of cattle were washed away. The study also found that the Nepal’s Building Codes were not properly enforced, which resulted in poor housing., the building construction materials are another culprit of the poor quality buildings in Kathmandu Valley along with the design of the residential structures. The study would like to suggest that the building codes should be implemented and the laws and bylaws prepared by the concerned authority should be strongly enforced. Furthermore, the practice of building designing of the residential houses by the owner themselves should be banned.
Abstract: Natural disasters are counterproductive to developing countries’ economic growth, as they may be accompanied by a reduction in the Gross Domestic Product (GDP), rise in imports, and deterioration in fiscal balances. The research was conducted during the period from September to December 2019. The main goal of this analysis was to find out the weakn...
Show More
-
Strengthening of Corroded RC Bridge Piers Subjected to Seismic Loads Using UHPFRC Jacketing
Heba A. Mohamed,
Mohamed Husain,
Sayed Ahmed
Issue:
Volume 4, Issue 2, December 2020
Pages:
61-76
Received:
5 November 2020
Accepted:
16 November 2020
Published:
24 November 2020
Abstract: Corrosion of steel reinforcement is the main damage issue for the efficiency and performance of reinforced concrete (RC) bridge piers located in aggressive environments. In this study, the possibility of strengthening corroded RC bridge piers with high corrosion leveled by ultra-high performance fiber RC (UHPFRC) jacketing was investigated numerically. The model of nonlinear 3-D finite-element (FE) was constructed by using ANSYS software. The parameters of axial force ratio, longitudinal reinforcement ratio, aspect ratio, and transverse reinforcement ratio were studied to determine their effect on the lateral load resistance of strengthening corroded RC bridge piers. The verification carried out between the constructed FE and the experimental results of ten RC bridge piers in four experimental studies. The performance of RC bridge piers under cyclic lateral displacement and axial force was studied with different ratios. Finally, a practical model to calculate the lateral load resistance of corroded RC bridge piers was proposed. The results of this research suggest that this technique could be applied for existing concrete bridge exposed in the marine environment whereas, the concentration of corrosive chlorides are high and can also use for any shape of a column and this technique allows keeping the initial dimension of the column.
Abstract: Corrosion of steel reinforcement is the main damage issue for the efficiency and performance of reinforced concrete (RC) bridge piers located in aggressive environments. In this study, the possibility of strengthening corroded RC bridge piers with high corrosion leveled by ultra-high performance fiber RC (UHPFRC) jacketing was investigated numerica...
Show More
-
The Effect of Sugarcane Bagasse Ash on the Properties of Portland Limestone Cement
Olubajo Olumide Olu,
Nuuman Aminu,
Likita Nazif Sabo
Issue:
Volume 4, Issue 2, December 2020
Pages:
77-87
Received:
7 November 2020
Accepted:
21 November 2020
Published:
4 December 2020
Abstract: This paper tries to investigate sugarcane bagasse ash (SCBA) as a cement replacement material and its effect on the water consistency, setting times, soundness, specific gravity, water absorption and mortar compressive strength of SCBA-Portland limestone cement (PLC) blend at cement replacement from 0 -15 wt.% at interval of 2.5 wt.%. Calcination of sugarcane bagasse was conducted and the optimum condition was obtained ash at 650°C at 90 mins with a higher Si + Al + Fe content from nine compositional analysis of ashes obtained via X-ray fluorescence spectrometer and then employed as cement replacement material for this research work. The consistency and setting times of the blended cement samples were carried on paste using Vicat apparatus while the soundness, specific gravity and compressive strength using Le Chatelier apparatus, density bottle and strength testing machine respectively according to ASTM standards respectively. Results showed an increase in the water consistency and setting times of SCBA cement pastes as SCBA content was increased from 2.5 – 15wt.% which was attributed to unburnt carbon present in the ash due to its high LOI. The elongated setting times could also due to clinker diminution by cement replacement with SCBA and high-water demand. The SCBA cement blends produced accelerated setting time results compared to PLC owing to lime present in SCBA which enhances early hydration. The specific gravity diminished while the volume expansion of the SCBA cement pastes experienced an increase as SCBA was increased due to lower density of SCBA compared to PLC and increased lime content due to increased SCBA content respectively. An increase in the mortar compressive strengths of SCBA cement blends was experienced as the curing days progressed from 3 to 60 days. PLC blended with SCBA produced an enhanced early strength due to the presence of lime which tends to accelerate the rate of formation of hydration assembly. Whereas, at a high cement replacement of 12.5 wt.% SCBA produced exceptional mortar compressive strength especially at 60 days despite clinker diminution indicating pozzolanic activity due to SCBA inclusion. The optimal cement replacement with SCBA was observed at 5 wt.% in comparison with control especially at 28 days and did not adversely affect its strength owing to pozzolanic activity.
Abstract: This paper tries to investigate sugarcane bagasse ash (SCBA) as a cement replacement material and its effect on the water consistency, setting times, soundness, specific gravity, water absorption and mortar compressive strength of SCBA-Portland limestone cement (PLC) blend at cement replacement from 0 -15 wt.% at interval of 2.5 wt.%. Calcination o...
Show More
-
Effect of Saw Dust Ash and Eggshell Powder on the Properties of Cement Blends
Issue:
Volume 4, Issue 2, December 2020
Pages:
88-99
Received:
29 November 2020
Accepted:
11 December 2020
Published:
22 December 2020
Abstract: The presence of calcium hydroxide (CH) can pose deteriorating effect on the durability of the cement from the inclusion of Eggshell powder (ESP) into the cement matrix. The incorporation of supplementary cementitious materials (SCM) such as Saw dust ash (SDA) could improve the properties of ESP-cement blends by eliminating some undesirable effects at the later age. This paper tries to explore the effect of possibility of replacing eggshell powder (ESP) cement blend with SDA and cement replacement on the properties such as consistence, setting times, volume expansion and strength gain. Saw dust was calcined at 600°C for 1 hour and sieved with 90µm sieve to obtain SDA. Portland limestone cement CEM II A-L was blended with ESP was replaced with SDA between 0 – 20 wt.% at 5 wt.% intervals and 0 -12.5 wt.% at 2.5 wt.% interval for physical properties and mortar compressive strength using 50 mm cubes with mixing ratio 1:3:5 (water, binder and sand) respectively. The chemical analysis of SDA revealed a high silica content (56.81 wt.%) with SiO2+Al2O3+Fe2O3 > 70% (72.2 wt.%), thus classified as Class F pozzolan according to ASTM C618 while ESP indicated a high lime content (48.5 wt.%) and considered a filler. Results indicated an increase in the consistence and setting time of the ternary blends as ESP was replaced with SDA owing to the unburnt carbon present in the SDA as well as clinker diminution. Likewise, an increase in the cement replacement led to an increase in water consistence and setting times. The retarded setting times of SDA-ESP cement blends could be attributed to increased water required due to SDA’s unburnt carbon whereas, ESP-cement blend produced accelerated setting times. A decrease in the volume expansion of the cement blends was observed as ESP was replaced with SDA which could be attributed to the decrease in the available lime while an increase in the volume expansion was also experienced as the cement replacement was increased from 0 – 20 wt.% at various SDA/SDA-ESP ratios from 0 – 0.8 except ratio of 1.0. The mortar compressive strength of cement blended with ESP and SDA experienced an increase as curing age was lengthened despite clinker diminution. This enhanced strength could be linked with SDA’s pozzolanic reactivity, provision of nucleation sites and formation of muscovite resulting in denser CSH with the optimal cement replacement observed at 5 wt.% with SDA/SDA-ESP ratio of 0.2 and 0.4 respectively.
Abstract: The presence of calcium hydroxide (CH) can pose deteriorating effect on the durability of the cement from the inclusion of Eggshell powder (ESP) into the cement matrix. The incorporation of supplementary cementitious materials (SCM) such as Saw dust ash (SDA) could improve the properties of ESP-cement blends by eliminating some undesirable effects ...
Show More
