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Several materials such as tuff and Tripoli which is naturally occurring and industrial by-products wastes as high calcium ash and slag were investigated as cement substitutes in this paper. Compressive strength of various standard mortar samples have been tested at 7 and 28 days. The obtained results show that these materials have improved the prop...
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... bond strength between cement substitutes and concrete materials is related to the interface properties, interface fracture mechanics and most likely to the crystal. The mode of crystal (that is, phanertic, aphanertic and glassy) play a significant role in determining the success of the substitutes. The loadings will impart both tensile and compressive normal and shear stresses at the interface, and thus failure will be under multi- component stresses. The development of the self cementaceous properties and strength are controlled by the additive content and the curing period. The additive is similar to a great extent to the Portland cement. The results are obtained through the standard mixtures of each sample ( Table 4). The mixtures are prepared and cured under the same standard procedures and conditions. Figure 1 show the effect of curing time on Tripoli which improve that the Tripoli reacts with OPC. This is because it has micro crystalline original and a high content of SiO 2 and CaO reacts with cement (Table 5). The strength of mortar increases as the Tripoli content increases up to specific value (that is, 20%) and then it has no effect on strength up to 40% content. The content of Tripoli more than 40% has adverse effect because the strength decreases as shown in Figure 2. At fixation point (10% of Tripoli content) the strength improved 30% from native sample after 28 days. On the other hand, the strength increases by 14% after 7 days for the same Tripoli content. This is an improvement on the fact that the Tripoli reacts with time. The well known reaction between the elite (C S) and water is The extra Portlandite Ca(OH) 2 will react with SiO 2 from Tripoli to produce Belit which will cause an increase in the strength by 30% as shown in Figure 2. The extra Belit ( 2CaOSiO 2 ) which is due to the addtion of Tripoli is appearantly resposible for the increase in compressive strength. From the obtained results in Figure 3, it is clear that the mortar strength has increased by 22% of ash fixation point after 28 days, whilst, at 7 days an increase of 14% were observed. The fixation point is at 10% ash content. The ash and Portland cement are essentially composed of lime (CaO). Silica (SiO 2 ) and alumina (Al 2 O 3 ) are present at higher concentrations in the Portland cement and react with CaO at about 1425°C to form alite. Heat treatment of the bituminous rocks and Portland cement raw material involves dehydration, thermal decomposition of clay minerals (300 to 650°C), decomposition of calcite (greater than 800°C), the formation of belite (C 2 S), tricalcium aluminate (C 3 A), and tetracalcium alumina ferrite (C AF). The liquid phase ...
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Citations
... Tripoli is used as a thermal insulation material due to its low thermal conductivity 8 . It is used as a construction material for cement substitutes in concrete production 17 . Recently, Jordanian Tripoli has been exploited as a potential industrial catalyst [5][6][7] . ...
Greywater, a byproduct of domestic activities, contains various contaminants including sodium ions which can adversely affect soil and plant health and industrial processes. This study explores the use of Tripoli, a sedimentary rock abundant in Jordan and its modified forms as potential adsorbents for sodium removal from greywater. X-ray fluorescence analysis revealed significant changes in chemical composition of Tripoli upon treatment with sulfuric acid and hydrochloric acid. Kinetic studies using the Weber and Morris intra-particle diffusion model demonstrated a high degree of agreement between experimental data and model predictions, with the rate constant (K) indicating enhanced intra-particle diffusion in samples treated at 1000°C. These findings highlight the potential of Tripoli and its modified forms as cost-effective and environmentally friendly adsorbents for sodium removal from greywater.
... Accurate modeling of beam deflection on an elastic foundation is fundamental for materials and their exploitation in structural engineering [23][24][25]. A dynamic approach is therefore essential to assess the displacement of the ground under the action of different types of loads that can be punctual, distributed or mobile. ...
Introduction The efects of the time-delay on the dynamics of the nonlinear beam on elastic foundation under vibrating
moving external load are analyzed and a controller built in order to avoid chaos in the system. The moving load carries out
both a horizontal motion with speed v and transverse harmonic oscillations, with angular frequency ω.
Materials and methods By using the formulation of Lagrange as well as geometric analysis, the nonlinear equation of the
system with time-delay is established. In this case the Winkler-type model of elastic foundation soil that acts on its bottom
interface (soil-beam) is used. The equilibrium points are next found, their stability studied and the condition of Hopf bifurca-
tion established as function of time delay. Next by using the Melnikov process, the analytical constraints necessary to have
chaos or not as behaviors of the system are sought, which are confrmed by numerical investigations, with plotting of the
time series, Lyapunov exponent and the bifurcation diagram, which are used to study the effects of time delay τ, which is
chosen as control parameter.
Conclusion The results show that when the value of τ is small, the ergodic tori and resonance cycles with diferent rota-
tion numbers on the torus can appear in the system. When the value of τ increases the chaos behaviors take place in the
system. Taking into account the fact that chaotic situations are considered as disturbance and are harmful for operation, the
control method based on the parameter τ is proposed, with the aim to quench and also to prevent chaotic behaviors.
... Accurate modeling of beam deflection on an elastic foundation is fundamental for materials and their exploitation in structural engineering [23][24][25]. A dynamic approach is therefore essential to assess the displacement of the ground under the action of different types of loads that can be punctual, distributed or mobile. ...
... Alkalis consumption takes place through alkali pozzolanic reaction to produce extra calcium silicate hydrate (C-S-H) when high calcium ash is added to mortars (Abdul Hadi et al. Through utilization of natural and industrial mineral admixtures as cement substitutes, strength was increased by adding some siliceous additives to sand cement mortars as reported by (Maaitah, et al. 2015). The capillary pores were decreased and the ASR was inhibited through immobility of alkali ions. ...
The following work aims at investigating the utilization of meta-kaolin and calcined brown smectite rich clays as inhibitors of alkali silica reaction (ASR) and improving the compressive strength in Type 1 ordinary Portland cement mortars including sand size chert or silicified limestone. Mortars were cured and tested at 56 days age. The compressive strength values increased to 40 MPa for the sample with 10% of Metakaolin-and 3.64% of chert content. The compressive strength values increased to 30 MPa when calcined brown clay was used instead of Meta-kaolin at the same proportion of chert.. Maximum compressive strength values of 36 Mpa and 30 Mpa were achieved when metakaolin and calcined brown clay were added to the reference mortars at a range of 5-10% and 8% respectively. Compressive strength was varied according to reactive aggregate type and percent in addition to the calcined brown clay and meta-kaolin content in the tested mortars. Scanning electron Microscope images (SEM) have indicated the absence of cracks usually related to swelling silica gel due to the consumption of the gel through its reaction with kaolin and calcined brown clay.
The aim of the study was to evaluate creep and shrinkage of concrete beams containing tuff aggregates (TA) as a partial replacement of coarse aggregate (CA). This was done at 0, 12.5, 25, 50, 75 and 100 % replacement levels. The methods used was characterization of TA, CA and Fine Aggregates (FA), mineralogical characterization of TA, compressive strength, modulus of elasticity of the cast concrete and loading 0.2 x 0.2 x 1.0 m beam specimens with dead weights for 60 days. Four beams of C45 were cast to test creep, whereby two had 0 % replacement and another two had 100 % replacement levels of CA. In each of the two sets, one beam was testing for creep deformation while another unsealed was tested for shrinkage. The maximum value of 0.00317 mm/m and 0.000236 mm/m of the 0 % and 100 % replacements were measured. However, there was an in-crease in shrinkage with time. Shear strain increased with time, whereby Normal Weight Concrete (NWC) produced lower values than Light Weight Concrete (LWC). The strain of reinforcements for the NWC and LWC was measured to be 0.000473 mm/m and 0.000427 mm/m, respectively. LWC experienced higher total bottom strains (creep + shrinkage included) than NWC at 694 and 360 micro strains, respectively. LWC produced higher creep coefficient values of 1.63 while NWC was 0.6. ACI and BS EN models produced a value of 0.64 and 0.597, respectively. Thus, it is concluded that LWC produces lower compressive strength, modulus of elasticity, and higher creep values than NWC. NWC experiences higher shrinkage than LWC owing to continued internal curing that reduces autogenous shrinkage.
Purpose. The article highlights research of the influence of fine concrete composition based on blast-furnace slag on general material properties. Time of the concrete treatment in the mixer activator is included to the influence research. Methodology. There was realized full factor experiment of 22 type with following variables: cement versus blast-furnace granulose slag ratio (X1) and time of the treatment in the mixer-activator (X2). Controlled properties are: early concrete strength (Y1=f7 day), normal concrete strength (Y2=f28 day) and average density of the concrete (Y3=ρ), hardened in normal conditions. Findings. Regress model analysis showed that decrease of the aggregate volume in concrete and increase of the mixing time grows up the strength and density of concrete. Different composition of the concrete also significantly affects concrete properties. Thus, for the same treatment time normal concrete strength at 28-day-old reduces by about 30% for compositions proportions 1:3 and 1:4, by 22% between a 1:4 and 1:5 and by 13% for 1:5 and 1:6 cases. The same behavior is obtained for early concrete strength. Density of concrete is not influenced and influence curve is almost flat. The difference between density values for different composition proportions 1:3 and 1:9 is 7.6% at equal mixture time. The increment of mixture processing time of 6 s increase normal concrete strength at 28-day-old about 7-8 % for all compositions in the studied range. Early strength values differ by 12-14 % between treatment time 30 and 36 seconds respectively. Every next six second increase step in treatment time reduce this difference by 1% for every mix compositions. There is practically no change of concrete density during the mixture time varying. Total change is 1-2% for 6 s in the entire research range for all compositions. Originality. For the first time the regression equations were determined, linking the duration of the activation of fine-grained concrete mix and its composition with the basic properties of concrete. Practical value. Regression equations and graphical surface can provide required concrete composition for the established early and normal concrete strength as well as concrete density.
