Performance of Cement–Fly Ash Masonry Mortar with Sand from Mine Overburden as an Environment-Friendly Alternative to Conventional Fine Aggregate

Experimental investigation of drying shrinkage cracking of composite mortars incorporating crushed tile fine aggregate

The shrinkage behavior of cementitious materials mixed with seawater is investigated. Cement mortar mixtures were prepared with two water-to-cementitious materials ratios (w/cm = 0.36 and 0.45), two binder compositions (namely, ordinary portland cement (OPC) and OPC with 20 % fly ash replacement), and two types of water (tap water and seawater). The autogenous and drying shrinkage behavior of these mixtures are examined using ASTM standard test methods for 65 days. The use of seawater as mixing water increased the autogenous shrinkage. At w/cm 0.36, the ultimate autogenous shrinkage increased from 213 μs in the mixture with tap water to 387 μs in the mixture with seawater; the corresponding values were 149 and 314 μs, respectively, for mixtures with w/cm 0.45. An acceleration of the cement hydration at early ages caused by the seawater is identified as the cause of the increase in autogenous shrinkage in mixtures with seawater. At w/cm 0.36, seawater did not have a strong effect on the drying shrinkage, and tested mixtures had ultimate drying shrinkage values between 543 and 663 μs. At w/cm 0.45, in mixtures without fly ash, ultimate drying shrinkage increased from 838 μs in the mixture with tap water to 1,027 μs in the mixture with seawater. In mixtures with fly ash, the ultimate drying shrinkage increased from 738 μs in the mixture with tap water to 1,370 μs in the mixture with seawater. The drastic increase in the drying shrinkage in mixtures containing fly ash and seawater at w/cm 0.45 seems to be due to changes in mass loss behavior and the development of a finer pore size distribution. In applications where drying shrinkage may be a concern, the use of fly ash in seawater-mixed concrete could be problematic and lead to increased cracking risk. While the trends observed here will also hold in concrete, quantifying drying shrinkage and cracking of concrete based on the drying shrinkage of mortar mixtures is complex and depends on many other factors.

New types of materials have been studied to substitute common aggregates in concrete and mortars. Due to concerns of sustainability, some research has also been made about the recycling and reuse of discarded materials from construction waste. Porcelain electrical isolators, crushed in fine particle size, can serve as a substitute for the common fine aggregate, because porcelain electrical isolators have similar chemical and physical properties to river sand. Their utilization gives mortar as good a performance as it does in conventional concrete, as in relation to its compression strength and absorption index.

Systematic comparison of different recycled fine aggregates from construction and demolition wastes in OPC concrete and PPC concrete

Concrete is a combination of cement, fine aggregate, coarse aggregate, water and admixtures. According to world coal association survey over 4.1 billion tons of Ordinary port land cement (OPC) was used across globally in 2020 and also use of OPC emits CO2 to the atmosphere.In order to overcome the problem, a search for alternative materials is the need of the hour and apart from cement, fine aggregate is also important additive to concrete. Due to the speedyconstruction rate deficiency of materials occurs reduction in natural aggregates causes problems like dredging of sand in large scale which creates environmental imbalance. The solution is utilisation of Fly ash, silica fume, Ground granulated blast furnace slag(GGBS) which are comes under Industrial by-products. The disposal of Industrial by-product should done properly, else it will cause land pollution. In this present study silica fume, fly ashes are replaced in OPC and fine aggregate with Granulated blast furnace slag(GBFS). The experimental work execute in order to determine mechanical properties such as compression, split tensile and flexural strength of concrete with age 3,7 and 28 days at various combinations of cement with fly ash varies 20%,30%,40% and constant 8%of silica fume and fine aggregate replaces with Granulated blast furnace slag of 30%,40% and 50% in M40 grade concrete with water-cement ratio 0.38. As per experimental results conclusions were drawn. As per the experimental results it is recommended that OPC is replaced with 8% of silica fume, 20% of fly ash and fine aggregate replaced with 40% of GBFS achieved optimum strength.

To reduce drying shrinkage of AASC mortar (AASM), mixed aggregate mixed with river sand (RS) and silica sand in three sizes was used to investigate the effect of the physical properties of mixed aggregate on shrinkage reduction. A mixture of river sand (0.2-0.8 mm), S1 (2.5-5.0 mm), S2 (1.6-2.5 mm), and S3 (1.21-160 mm) had river sand-silica sand mean diameter ratios (dr) of 7.68 (S1/RS), 3.75 (S2/RS), and 3.02 (S3/RS). The compressive strength and drying shrinkage characteristics of mixed aggregates according to fineness modulus, surface area, bulk density, and pore space were investigated. It had the highest bulk density and lowest porosity at a substitution ratio of 50%, but the highest strength was measured at a substitution ratio of 50% or less. High mechanical properties were shown when the fineness modulus of the mixed aggregate was in the range of 2.25-3.75 and the surface area was in the range of 2.25-4.25 m2/kg. As the substitution rate of silica sand increased, drying shrinkage decreased. In particular, the drying shrinkage of RS + S1 mixed aggregate mixed with S1 silica sand, which had the largest particle size, was the smallest. When silica sand or river sand was used alone, the drying shrinkage of the sample manufactured only with S1, which has the largest particle size of silica sand, was the smallest among all mixes. Compared to RS, at a 5% activator concentration, drying shrinkage was reduced by approximately 40% for S1, 27% for S2, and 19% for S3. At a 10% concentration, S1 showed a reduction effect of 39%, S2 by 28%, and S3 by 13%. As a result of this study, it was confirmed that the drying shrinkage of AASM could be reduced simply by controlling the physical properties of the aggregate mixed with two types of aggregate. This is believed to have a synergistic effect in reducing drying shrinkage when combined with various reduction methods published in previous studies on AASM shrinkage reduction. However, additional research is needed to analyze the correlation and influencing factors between the strength, pore structure, and drying shrinkage of AASM using mixed aggregate.

Introduction: the article discusses the effect of the complex of active mineral additives consisting of silica and fly ash, and a fine aggregate, including finely ground natural-white quartz sand for partial replacement of river sand, on the mechanical properties of high-strength concrete containing steel fiber. Materials and methods: high-strength concrete containing Dramix®3D 65/35 steel fiber in the amount of 100 kg per 1 m3 of concrete mixture was suggested where 22% to 100% of river sand was replaced by finely ground white natural sand of the particle size of 5 to 1800 μm and containing the complex of active mineral additives for partial replacement of cement as part of a multicomponent binder, consisting of low-calcium fly ash of thermal power plants and silica and containing, respectively, 20, 30, 40% fly ash and from 5 to 15% silica by weight of the binder. Results: research results have shown that 100% replacement of river sand with finely ground natural white sand, in concrete containing 20% of the mass as part of a multicomponent binder, fly ash and from 5 to 15% by weight of silica, contributes to the increase of its strength properties: the values of concrete compressive strength after 28 days were in the range from 118.5 to 128 MPa, tensile strength during bending and splitting, respectively, from 18.8 to 25.4 MPa and from 10.2 to 11.9 MPa, which is higher than the strength of concrete samples containing river sand. Conclusions: the achieved results have demonstrated the efficiency of using finely ground natural white sand as an alternative to river sand for producing high-strength concrete, thus helping to save the river sand resources in Vietnam. The use of fly ash and micro silicon, which are power and metallurgy wastes, as part of a multicomponent binder in order to partially replace cement reduces the carbon footprint in the production of binders and will also have a beneficial effect on environmental protection against industrial waste pollution.

This study is a preliminary investigation of the independent utilization of two types of fly ash (FA)–FA Type C and FA Type F-as partial replacement of fine aggregate (sand) and cement in Portland cement concrete (PCC) mixes. The main objective was to determine an optimum substitution range for each type of FA that would offer well-performing concrete in terms of workability, compressive strength, and durability. To this end, multiple concrete batches were prepared, incorporating each type of FA at four different levels: 5%, 10%, 15%, and 20% by weight of fine aggregate replacement and 10%, 20%, 30%, and 40% by weight for cement replacement. Then, concrete samples (100 mm diameter × 200 mm tall cylinders) were cast from each batch and were moisture-cured for 7, 14, and 28 days prior to testing. The addition of FA contributed positively to the strength development at specific replacement levels: all percentages for both FA Type C and Type F for fine aggregate replacement and up to 30% FA content for both Type C and F for cement replacement, 10% for both FA Type C and Type F provided the higher strength for aggregate replacement, and 10–20% for both types of FA provided the higher strength for cement replacement. Furthermore, these additions of FA exhibited comparable workability and durability except for FA Type F, which did not exhibit comparable workability for aggregate replacement. FA Type C can be recommended for both early and long-term strength for fine aggregate replacement, whereas FA Type C is suggested to be used for early strength and Type F provides for long-term strength for cement replacement. Type C provides better durability and Type F provides better workability for cement replacement.

Background/Objectives: The construction industry mainly aims at sustainable construction with the available natural resources by reducing the negative environmental impacts on environment. Over a period of time, the scarcity of fine aggregate has become one of the most complex and challenging problem in the construction field. In India, the escalation in the price of natural river sand leads to the demand in the alternate construction material by considering Manufactured Sand (M sand) as a fine aggregate which solve the problem of scarcity. The focus of the present investigation is to assess the potential of using Manufactured sand as a replacement to fine aggregate in M60 grade concrete. Fly ash and silica fume also used to reduce the cement content and as a voids filler material. Methods Statistical Analysis: In the present investigation, it is aimed at to study 0, 25, 50, 75 and 100% of traditional fine aggregate replaced with M- sand. The test results are obtained by conducting compressive strength test, split tensile strength test and flexural strength test after 3, 14, 28 and 60 days of curing. Findings: The strength characteristics of concrete shows higher its strength with the partial and 100% replacement of M-sand in fine aggregate for all the curing period studied. An increase of 6.27% and 14.65 % in compressive and split tensile strength is observed by the full replacement of river sand with M- sand at the curing period of 28th day. Application/Improvements: Use of Manufactured sand in high strength concrete serves better alternative for the river sand. The utilization of manufactured sand in concrete as fine aggregate reduces the problem in scarcity of natural sand and reduces the time delay and cost of the construction. Keywords: Compressive Strength, High Strength, Manufacatured Sand, River Sand

The addition of ground olive stones in the manufacture of mortar bricks reduces their thermal conductivity coefficient and increases heat exchange insulation. So, it can improve energy efficiency and reduce the energy demand of buildings. This research analyzes, from other points of view, the economic, social and environmental impacts of the doping of GERO mortar bricks with ground olive stone in a percentage between 5% and 15% by volume of fine aggregate for use in building construction. The study focuses mainly on the region of Andalusia, Spain, where large quantities of olive stones are collected as waste from olive oil production. The economic analysis shows how the use of ground olive stones as a partial replacement of fine aggregate in mortar can generate significant savings and economic returns in the medium term (10–20 years) by reducing conventional energy consumption in heating and air conditioning installations. Finally, the Environmental Life Cycle Analysis shows that the use of ground olive stones in GERO perforated bricks reduces environmental impacts in the medium term. In summary, the research concludes that the doping of mortar bricks with ground olive stones can have a positive impact on the economy, society and the environment, and represents a sustainable and cost-effective alternative for the construction industry.

Utilization of ceramic waste as fine aggregate within Portland cement and fly ash concretes

Workability Strength and Elastic Properties of Cement Mortar with Pond Ash as Fine Aggregates

Utilization of fine recycled aggregates in concrete with fly ash and steel slag

Cement Treated Base (CTB) is a pavement layer located between the sub-base and surface layers. This pavement layer uses fine aggregate (sand) and cement as a binder. Fly ash is coal burning waste that can be used as an added material for road pavement. This study aimed to analyze the use of fly ash in the cement treated base pavement mixture. Fly ash was used as a substitute of cement. The composition used consists of fine aggregate (sand), cement, fly ash and water. The compressive strength test was carried out on variations in the composition of the test object. The requirements for CTB specifications were to have compressive strength test results ranging between 45 kg/cm2 – 55 kg/cm2 at the age of the test object for 7 days. After being tested, it was found that the composition of 70% fine aggregate (sand), 5% Portland cement, and 25% fly ash had an average compressive strength of 49.823 kg/cm2.

Alkali-silica reaction of ferronickel slag fine aggregate in Portland cement and alkali-activated slag mortars: Pessimum effect investigation