Influence of Several Nano Minerals on The Mechanical Properties of Fresh and hardened Concrete

The current study aims at obtaining the influence of adding several nano-minerals on the mechanical properties of fresh and hardened concrete. Four types of Nano minerals were investigated in this work; namely: Brown Iron Oxide, Barium Sulfate, Titanium Dioxide and Poly Acrylic Acid. Five contents of each nano-minerals were studied. A range of contents starting from 0.5% to 2.5% with an increment of 0.5% by cement content of Brown Iron Oxide and Barium Sulfate was investigated. The Titanium Dioxide and Poly Acrylic Acid were added to concrete in percentages of 1% to 5% with an increment of 1% by cement content. Adding 5% Poly Acrylic Acid to the other three nano-minerals at selected contents separately was also studied. The measured mechanical properties of concrete comprised slump value, 7 and 28 days compressive strength. Some of the results revealed that there was 24% increase in the slump value corresponding to every 1% increase in PAA content. An improvement of 6.9% in the 28 days compressive strength was measured at every 0.5% increase of Brown Iron Oxide. It was also found that by adding 5% Poly Acrylic Acid and 2.5% Brown Iron Oxide to the concrete at the same time, the slump increased from 90 mm to 170 mm (88.9% increase) and the 28 days compressive strength improved from 37.37 kg/cm2 to 49.35 kg/cm2 (32.1% increase)

Effect of forta-ferro fibers on fresh and mechanical properties of ultra high performance self compacting concrete

This research presents an experimental study of the effect of polypropylene fiber on Ultra High Performance Self Compacting Concrete (UHPSCC). Local available materials and inclusion of polypropylene fiber with different quantities are investigated to produce UHPSCC. The experimental program comprises investigating four different quantities of polypropylene fiber namely; 4.55, 9.1, 13.65 and 18.2 kg/m3. The current study focuses on the influence of polypropylene fiber on both fresh and hardened properties such as flowability, filling ability, passing ability, compressive strength, splitting strength and flexural strength of UHPSCC. The results revealed that addition of polypropylene fibers improves the compressive strength of UHPSCC in the range of 1% to 7% compared with the non-fibrous UHPSCC. They also enhance the tensile strength in the range of 20% to 30%, and improve the flexural strength within the range of 16% to 26%. Moreover, it is concluded that the optimum polypropylene fiber is 13.65 kg/m3 of concrete with splitting tensile strength of 8MPa and flexural strength of 10MPa

Design Optimization of Semi-Rigidly Connected Steel Frames Using Harmony Search Algorithm

In this paper, a design optimization algorithm is presented for non-linear steel frames with semi-rigid beamcolumnconnections using harmony search algorithm. The design algorithm obtains the minimum steel weight by selecting from a standard set of steel sections. Strength constraints of American Institute of Steel Construction - Load and Resistance Factor Design (AISC-LRFD) specification, displacement, deflection, size constraint and lateral torsional bulking are imposed on frames. Harmony search (HS) is a recently developed meta-heuristic search algorithm which is based on the analogy between the natural musical performance and searching the solutions to optimization problems. The HS algorithm accounts for the effect of connections’ flexibility and the geometric non-linearity of the members. The Frye–Morris polynomial model is used for modeling semi-rigid connections. Two design examples with extended end plate without column stiffeners are presented to demonstrate the application and validity of the algorithm

Investigating the Effect of Sulfate Attack on Compressive Strength of Recycled Aggregate Concrete

This research aimed at studying the effect of sulfate attack on the compressive concrete strength with various percentages of recycled aggregate replacements (0%, 30%, 60% and 100%). Water cement ratio (0.42) are used, MgSO4 solution was used with two concentration (6% and 9 %) to represent the effect of sulfate attack on the concrete compressive strength. The experimental tests focused on physical properties of recycled aggregate; density, unit weight, sieve analysis, Los Angles test and specific gravity. Tests have also been performed on 108 concrete cubes samples at 7 days, 14 days and 28 days for compressive strength. The results of  compressive strength at 28 days using (0%, 30%, 60% and 100%) recycled aggregate are (330, 280, 266 and 244) Kg/cm2 respectively, with reduction in compressive strength was (15.2%, 19.4% and 26%)  for replacement ratio (30%, 60% and 100%) respectively. MgSO4 solution has an effect on compressive strength after 90 days of immersion in 6% and 9% concentrated of MgSO4 solution. The results of this study show that the reduction in compressive strength using recycled aggregate is more sensitive against the sulfate attack compared with natural aggregate

Effect of aggressive chemicals on durability and microstructure properties of concrete containing crushed new concrete aggregate and non-traditional supplementary cementitious …

The increasing awareness and usage of traditional supplementary cementitious materials (SCMs) in concrete have pressured the construction industry to look for alternatives to overcome the concerns over their plentiful availability in the future. This research illustrates the performance of recycled aggregate concrete prepared with the incorporation of available industrial by-products, namely rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) as alternatives for traditional SCMs. The effect of hydrochloric (HCl) acid and magnesium sulfate (MgSO 4) attack was evaluated by measuring the change in mass, compressive strength and microstructural analysis. The results revealed that the incorporation of RHA, POFA and POCP up to 30% minimizes concrete deterioration and loss in compressive strength when the specimens were exposed to HCl solution. In addition, the scanning electron

Assessment on engineering properties and CO2 emissions of recycled aggregate concrete incorporating waste products as supplements to Portland cement

This paper presents an experimental investigation on the durability properties and carbon dioxide (CO2) emissions of concrete developed using waste products. The concrete comprised of recycled concrete aggregate (RA) as a complete coarse aggregate replacement. In addition, rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) were used as replacement materials for cement at levels up to 30%. The supplementary cementitious materials (SCMs) were used in RA concrete with the aim of reducing the dependency on cement as a stand-alone binder. The compressive strength, water absorption, chloride-ion penetration and electrical resistivity were investigated for RA concrete containing SCMs. Moreover, the residual compressive strength was also examined along with the weight loss to check the elevated temperature resistance of RA concrete with SCMs. The results revealed that

Evaluation of industrial by-products as sustainable pozzolanic materials in recycled aggregate concrete

The utilization of traditional supplementary cementitious materials (SCMs) has become more intense in the concrete industry due to their better long-term properties. This research evaluates the fresh and hardened properties of concrete that was developed using a high amount of recycled aggregate (RA) incorporated with sustainable SCMs. Rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) were used as SCMs at 10%, 20% and 30% cement replacement levels to investigate their positive role in the performance of RA concrete. The results showed that the 10% replacement level of cement by RHA produced the highest strength at all ages tested. Although POFA and POCP were found to negatively affect the strengths at an early age, the hardened properties showed improvement after a relatively long curing time of 90 days. In addition, the targeted compressive strength of 30 MPa was achieved by using SCMs at levels up to 30%. Overall, the sustainable SCMs can reduce the quantity of cement required for concrete production, as well as reduce the conventional cement with the industrial by-products, which are considered as waste materials; thus, the concrete produced using up to 30% of SCMs as a replacement for cement could be considered as more environmentally-friendly concrete

Influence of Internal Curing on the Mechanical Properties of Normal Strength Concrete

The current study investigated the influence of internal curing on the mechanical properties of normal concrete produced at the Islamic University of Gaza (IUG) laboratories. Due to the high aborption capacity of the local broken pottery fragments, crushed pottery material was utilized in this study as the internal water storage source. The specific gravity and the absorp-tion capacity of the crushed pottery (CP) sieves were identified to ensure the suitability of such material. The current study investigated the partial replacement of 0%, 10%, 15%, 20% and 25% of fine aggregates with CP material. Slump tests were carried out for the CP smaples to obtain the effect of various contents on the workability of the mixes. The CP specimens were also prepared to obtain the mechanical properties, including the compressive strength and flexural strength. The com-pressive strength of the samples was obtained at ages of 7, 14 and 28 days. The optimum CP content was identified and applied to study the flexural strength. The results of the experiments showed that the use of the locally available crushed pottery as an internal curing material was effective in curing the concrete samples. The partial replacement of the natural fine aggregates with various contents of CP was also positive for the slump values. Further, the application of CP material was successful in improving the early compressive strength and flexural strength. A slight improvement in the 28-days strength results was revealed with the increasing content of CP. The slump and strength results indicated that 20% partial replacement of fine aggregates with CP materail was the optimum

Early stage cost estimation of buildings construction projects using artificial neural networks

A ISTRA ("|" Early stage cost estimate plays a significant role in any initial construction project decisions, despite the project scope has not yet been finalized and still very limited information regarding the detailed design is available during these early stages. This study aimed at developing an efficient model to estimate the cost of building construction projects at early stages using artificial neural networks. A database of 71 building projects is collected from the construction industry of the Gaza Strip. Several significant parameters were identified for the structural skeleton cost of the project and yet can be obtained from available engineering drawings and data at the pre-design stage of the project. The input layer of the Artificial Neural Networks (ANN) model comprised seven parameters, namely: ground floor area, typical floor area, number of storeys, number of columns, type of footing, number of elevators and