Properties Of New Concrete Research Articles

Exploring Current Techniques for Improving the Properties of New Concrete

In modern construction, the properties of new concrete are crucial for building quality and structural performance. Recent technological advancements have led to significant progress in enhancing the properties of new concrete. This study employs theoretical and experimental methods to explore the connection among shear stress and shear strain rate under vibration, the impact of aggregate substitution on concrete performance, and the rheological properties of moist shotcrete. The findings suggest that adjusting mix proportions and using additives can significantly improve concrete's strength, durability, and workability. This research provides engineers with a theoretical foundation for optimizing concrete mixtures and construction techniques, thereby improving overall building quality and construction efficiency. The findings suggest that sustainable materials can be used without compromising structural integrity, making the construction process more environmentally friendly while maintaining high performance standards. Furthermore, this study highlights the importance of understanding concrete behavior under various conditions to develop more resilient and long-lasting structures.

Effect of reactive coarse recycled aggregate with different expansion history on alkali silica reactivity and mechanical properties of new concrete

AbstractRecycled concrete aggregates (RCA) provide an environmentally friendly solution by reducing the depletion of natural resources. This study investigates the impact of the expansion history of RCA on its reactivity with alkalis in newly produced concrete. Parent concrete samples were collected from the RILEM AAR‐4 curing cabinet (60°C and >90% RH) to produce coarse RCA with four different expansion levels (0.00%, 0.05%, 0.12%, and 0.20%). The results show that the expansion levels of the new concrete mixtures decreased as the ASR expansion history of parent concrete increased. The 20‐week compressive strength and elastic modulus of the reactive aggregate concrete containing no mineral admixture and exposed to AAR‐4 test conditions were lower than those of their water‐cured counterparts. However, no decrease was observed in the elastic modulus of concrete mixtures that showed an expansion level lower than 0.03% (the maximum expansion for nonreactive aggregate as recommended by the RILEM AAR‐4 standard).

Effect of free and embedded polypropylene fibres recovered from concrete recycling on the properties of new concrete

This study aims at investigating the effect of incorporating different quantities of polypropylene fibres recovered during concrete recycling or embedded in recycled aggregates on the mechanical properties of new polypropylene fibre-reinforced concrete (PPFRC). Both recovered fibre (at replacement ratios of 0 %, 10 %, 30 % and 100 %) and recycled coarse aggregate (0 %, 100 %) were used in new concrete. Polypropylene fibre contents of 3 and 9 kg/m3 (0.33 % and 1.0 % by volume, respectively) were chosen for all concretes. The properties of recovered and virgin fibres were tested to determine the effect of recycling on fibre properties. The compressive strength, elastic modulus and stress–strain behaviour in compression were tested and a constitutive model was developed to fit the stress–strain behaviour of the PPFRC with mixed recovered and virgin fibres. The residual tensile strength was also tested for concretes with recovered fibres and fibres embedded in recycled aggregate. The results show that mixing of recovered and virgin fibres is feasible without significant effect on mechanical properties of concrete. At the same time, inclusion of recycled coarse aggregate from PPFRC recycling contributes to residual tensile strength through the presence of fibres embedded in the aggregate.

Influence of Optimum Particle Packing on the Macro and Micro Properties of Sustainable Concrete

In this research, the possibility of making eco-friendly concrete from available materials in the local United Arab Emirates (UAE) market was investigated. Supplementary cementitious materials, such as ground granulated blast-furnace slag (GGBS) and silica fume (SF), were utilized for decreasing the cement quantity, enhancing the particle size distribution and improving packing. In sum, 130 concrete specimens—cubes, cylinders, and prisms—from 10 different concrete mixes were tested to determine the enhancement levels in the fresh and hard properties of new concrete. The results showed the improved particle packing of the concrete, especially within the region of sizes 100–10,000 microns, produced by the Elkem Materials Mix Analyser (EMMA), closely matching the Andreassen theoretical model. The green concrete incorporating SF and GGBS possessed air content in the range 1.0–1.4% and compressive strength that is on average 11% higher than the well-packed concrete that did not contain SF or GGBS. Compared to the ACI 318 code’s predictions, the experimental findings of the optimally packed concrete’s moduli of rupture and elasticity were under-estimated by 55–69% and 0.8–8.8%, respectively. The rapid chloride permeability test (RCPT) showed results as low as 392 coulombs for mixes with supplementary cementitious materials, indicating very low chloride permeability. Microstructural analysis using a scanning electron microscope (SEM) demonstrated that concrete with supplementary materials has fewer voids, more homogeneous integration of ingredients, and an abundance of C-S-H products that supported the RCPT findings and tests of mechanical properties. The study demonstrated a significant decrease in carbon dioxide (CO2) emissions of concrete utilizing GGBS and SF and the financial feasibility of eco-friendly concrete in the UAE.

Identifying the influence of expanded clay concrete based on a binder from phosphorus slag on the strength of structures from leaked concrete

The paper presents the results of experimental studies of concrete and compressed reinforced concrete elements from cementless claydite-concrete. An experimental study of reinforced concrete elements with central and eccentric application of forces was carried out to determine their increased sensitivity. The construction material is cementless expanded clay concrete, obtained by a mixture of finely divided granular electrothermophosphorus slag. The tests were carried out on reinforced concrete compressed elements with central and eccentric application of longitudinal force to determine their bearing capacity. According to the test results, the strength and deformation properties of new concrete on a glass-slag binder and the calculation of reinforced concrete structures are checked. The selection of compositions of glass-slag claydite-concrete of various grades has been made. The use of concrete with a clinker-free binder in construction makes it possible to reduce the need for a scarce building material – cement. Studies of the physical and mechanical properties of glass-slag expanded clay concrete grades M50+M150 with a bulk density of 1,000–1,400 kg/m3 were carried out under a short-term static load. At the same time, the strength and deformation properties of glass-slag expanded clay concrete were studied under short-term action of compressive and tensile loads. The use of any new building material must be preceded by a comprehensive study of it – determination of its strength properties, study of concrete in the structure under load, etc. Building codes and regulations are adopted for the standard construction material, the properties of aggregates are not taken into account. Our studies show that the properties of fillers increase the strength properties of the structure when using claydite concrete on a glass-slag binder in reinforced concrete structures

Application and Microstructure Properties of Nanomaterials in New Concrete Materials

This article takes the application of nanomaterials in new concrete materials as the research object and explores the defects of nanomaterials in improving the toughness and tensile capacity of traditional concrete by analyzing the effects of nanomaterials on the structure and properties of new concrete. This article takes the application of nano‐SiO2 in new concrete materials as an example. Firstly, the experiment of preparing nanoconcrete was carried out, and then, aiming at the experimental results, a detailed analysis and discussion on the effects of nano‐SiO2 on the shrinkage, mechanical properties, and microstructure of the new concrete materials were carried out. The research results show that the cement paste with nano‐SiO2 is much better in chemical shrinkage than the cement paste without admixture, and the chemical shrinkage value of the cement paste with nano‐SiO2 increases significantly in the early setting stage. The chemical shrinkage values are 11.4%, 26.7%, 53.9%, and 94.2%, respectively, according to the amount of nano‐SiO2 added. With the extension of the setting period, the growth rate of the shrinkage value of cement paste slows down; nano‐SiO2 can improve the compressive capacity and strength of concrete, and with the increase of the amount of compressive strength, the value of compressive strength is also increasing. In the early stage of coagulation, when the nano‐SiO2 dosage is 1.6%, the compressive strength of the coagulation for 3 days is 39.02%. With the prolongation of the setting period, the increase in compressive strength continues to increase, but the growth rate slows down; the addition of nano‐SiO2 has changed the microstructure of concrete. Nano‐SiO2 has high pozzolanic activity, which can promote the hydration process of cement, and because of the small particles, it can fill the voids of concrete, thereby improving its compactness and mechanical strength.

Mechanical Properties of Concrete Using Recycled Aggregates Obtained from Old Paving Stones

Nowadays, construction, maintenance, reparation, rehabilitation, retrofitting, and demolition from infrastructure and buildings generate large amounts of urban waste, which usually are inadequately disposed due to high costs and technical limitations. On the other hand, the increasing demand for natural aggregates for concrete production seriously affects mountains and rivers as they are the source of these nonrenewable goods. Consequently, the recycling of aggregates for concrete is gaining attention worldwide as an alternative to reduce the environmental impacts caused by the extraction of nonrenewable goods and disposal of construction and demolition waste (C&DW). Therefore, this article describes the effect on the mechanical properties of new concrete using recycled aggregates obtained from old paving stones. Results show that replacing 50% by weight of the fine and coarse aggregate fractions in concrete with recycled aggregate does not meaningfully affect its mechanical behavior, making the use of recycled aggregates in new precast paving stones possible. Therefore, the latter can reduce environmental impacts and costs for developing infrastructure and building projects.

Partial Replacement of Fine Aggregates in Cement Mortar by using Pond Ash and Development of Low Cost Tiles

Pond ash is squanders and waste product of Thermal force plant, have been acquainted into Indian solid industry with save common assets of elements of cement. In India, a large portion of the Thermal force plants embrace wet technique for debris removal. Lake debris is gathered from Thermal force plant at the base, in that it contains critical measure of generally coarser particles (crossing from 150 microns to 2.36 mm). Lake debris usage assists with diminishing the utilization of normal assets. Additionally it is help to take care of the issue of removal of Pond debris since it contains enormous measure of substance mixes, for example, SiO2, Al2O3 and so on. These synthetic mixes (SiO2, Al2O3) are assumes a significant job in hydration response and assists with delivering bond between two nearby particles. Utilization of Pond Ash in concrete is a significant eco productivity drive. It is important to locate the specific appropriate rates of lake debris so it is chosen to use in differing rate as 0%, 5% 10%, 15%, 20%, 25%, 30%. Also, to check the properties of new concrete and solidified cement, for example, droop and compressive quality, rigidity, flexural quality individually. Likewise solid assumes a significant job in long life time of structure so it is additionally critical to check impact on strength by utilizing sulfate assault, chloride particle entrance, drying shrinkage. Study shows the essential properties of Pond ash. It likewise contrasts these properties and characteristic sand. Fractional substitution doesn't bring on any unfavorable impact on properties of new concrete. The outcome shows that solid invigorating great with fractional substitution of fine total. Just as Pond debris is the acceptable whenever utilized as filler material in concrete. Subsequently, it is appropriate to utilize lake debris as fine total or halfway supplanting with normal sand.

A review on fiber reinforced self compacting concrete addition with M-Sand

This review analyse the structural properties of the M-Sand addition with fiber reinforcerd Self Compacting concrete (SCC) is a high – execution solid that can traverse under its self-load to totally fill the structure work and self solidifies with no mechanical vibration. Comparison between the experimental results from the analysis exhibited that the proposed model provides satisfactorily predictions of ultimate compressive strength, failure strain, and stress-strain response. L-Box, U-Box, V-Funnel and J-Ring tests were performed to decide the properties of new concrete on both River sand and M sand. The properties of solidified cement on both R sand and M sand can likewise explored by leading the Flexural quality test. The test is directed after 28 days of restoring. The outcome of the review inferred that the Properties life time and workability of concrete.

Assessment of mechanical properties of concrete incorporating carbonated recycled concrete aggregates

An accelerated carbonation technique was employed to strengthen the quality of recycled concrete aggregates (RCAs) in this study. The properties of the carbonated RCAs and their influence on the mechanical properties of new concrete were then evaluated. Two types of RCAs, an old type of RCAs sourced from demolished old buildings and a new type of RCAs derived from a designed concrete mixture, were used. The chosen RCAs were firstly carbonated for 24 h in a carbonation chamber with a 100% CO2 concentration at a pressure level of 0.1 Bar and 5.0 Bar, respectively. The experimental results showed that the properties of RCAs were improved after the carbonation treatment. This resulted in performance enhancement of the new concrete prepared with the carbonated RCAs, especially an obvious increase of the mechanical strengths for the concrete prepared with the 100% carbonated new RCAs. Moreover, the replacement percentage of natural aggregates by the carbonated RCAs can be increased to 60% with an insignificant reduction in the mechanical properties of the new concrete.

Experimental Lnvestigation on Mechanical Characteristics and Environmental Effects on Rubber Concrete

The feasibility of the use of scrap tire rubber in concrete was investigated. The tests conducted in two groups: replacing of coarse aggregates with crumb rubber and cement particles with rubber powder. To distinguish the properties of new concrete, the following mechanical and durability tests were designed: compressive, tensile and flexural strength, permeability and water absorption. Rubber addition could affect the concrete properties depend on the type and percentage of the rubber added. Although the rubber addition modifies the mechanical characteristics of concrete in a way, but higher rubber content could not be useful. Concrete durability showed more dependency to the type of rubber instead of percentage of rubber. Moreover, to optimize the mechanical and durability of rubberized concrete, the useful percentage of rubber has been recommended.

Using Recycled Concrete Aggregates in New Zealand Ready-Mix Concrete Production

Motivations for adopting recycled concrete as an aggregate source include the preservation of natural resources, effective utilization of a growing waste stream, and financial and energy savings. Although current New Zealand practices include some use of crushed concrete in road construction, use of recycled concrete aggregate (RCA) in low specification concrete is currently infrequent and the use of recycled concrete as an aggregate source in structural concrete applications is rare. To make such recycling feasible, the properties of RCA must be related to the properties of new concrete that utilizes the recycled aggregates. In response to this need, a study was undertaken to investigate the feasibility of using RCA as a viable alternative to natural aggregate (NA) in the production of concrete manufactured in a conventional New Zealand ready mix concrete plant. Aggregate properties and hardened and fresh concrete properties of RCA concrete were studied and compared with the associated properties derived from NA concrete. Results indicated that RCA is a viable alternative to NA in the production of concrete. Furthermore, it was confirmed that the properties of RCA dictate the hardened properties of the reconstituted concrete and that RCA from certain strength placements limited the resulting possible strengths of concrete produced from it.

スラッジ混入コンクリートの諸特性に及ぼすスラッジの組成および凝結調整剤の再添加の影響

Authors have been studying for several years as for the effective utilization of sludge water produced in ready mixed concrete plant containing cement and fine particles of aggregate. Nowadays, JIS A 5308 permits the usage under 3 percent as solids of sludge for the unit content of cement of new concrete. This study, in order to utilize the larger quantity of sludge water than that now allowed in the mixing plants, is to obtain the basical data on the properties of fresh concrete and of hardened concrete. In this study, the influence of composition of sludge and double adding of setting retarder has been discussed experimentally on the view points of slump, bleeding, compressive strength and drying shrinkage. From the results of this study, it was clarified that in the range of cement: fine sand is from 1:1 to 8:1, the composition of sludge has no large influence on the properties of new concrete. And the double adding of setting retarder has no good effect on the improvement of properties of sludge.