Concrete Made Research Articles

The Aggregate’s Influences on Properties of Porous Pervious Concrete Made of Recycled Aggregates

In this study,different particle size’s aggregates ,different aggregate correction coefficients and different sand ratio were selected to study the aggregate’s influences on properties of porous pervious concrete made of recycled aggregates.The results shows that the 28-day compressive strength of concrete with single particle size is lower than those with two kinds of particle mixing ,as for the permeability coefficient, the former is much higher than the latter .With the aggregate correction coefficient’s increase,the 28-day compressive strengths of concrete increases first and then decreases, the permeability coefficient increases . The 28-day compressive strengths of concrete increases with the increase of the sand ratio. the permeability coefficient increases first ,decreases then.

Research on Performance of Concrete Made with Mineral Fillers and Fly Ash Admixed Desulphurization Gypsum

In order to improve the performance of concrete, reasonably use industrial waste and realize the sustainable development target of economy and environment, mineral admixtures have been widely used in concrete. But, widely using mineral admixtures reduces the overall performance of concrete, the reason is that the mineral admixtures dilutes the SO3 content in cementitious material, restricts generating the hydrates in the later concrete. If also add industrial by-products desulphurization gypsum in concrete, the added desulphurization gypsum as admixture not only improves the SO3 content in concrete, but also prime and crystal sulfate active, promote other admixtures pozzolanic effect, configuration effect and micro-aggregated effect. Experiments show that, when the desulphurization gypsum that added into cementitious material content is following 10%, in other words the desulphurization gypsum content is 3.1%, it can improve the mechanical performance of the concrete. Considering the early strength and work performance of cement, the desulphurization gypsum content that added into cementitious material should be controlled in the range of 8%, early strength increases by 16.9% and late strength also increases.

Strength Evaluation of Concrete Made with Dug-up Gravel from Southwestern Nigeria

Large expanses of natural deposits of gravel and sand are known to be available in many parts of the Southwestern Nigeria, which are being used for concrete production but with no standards. This study investigates the effects of using raw and washed dug-up gravel on the strength properties of concrete with a view to provide some standards for their usage. Field survey of quarry sites around Ile-Ife identified two commonly used dug-up gravel (Tiwantiwa), gravel A and (Majeroku), gravel B, which were selected for investigation. Prescribed mix proportions (measurements by weight) of 1:2:4 (cement:fine aggregate:washed/raw gravel) and 1:6 (cement:raw gravel) were used to produce the concrete cubes and beams for compressive and flexural strength tests. The results showed that using gravel A in raw form without sand and in washed form with sand have almost the same compressive strength (CS), while washing gravel B before use and with sand improved the CS of concrete. At 28 days, the CSs of concretes made from raw with no sand (RNS) of gravels A and B were 17.07 and 12.47 N/mm2, while those of raw with sand (RWS) and washed with sand (WWS) were 14.73 and 16.80 N/mm2 for gravel A and 11.93 and 16.00 N/mm2 for gravel B, respectively. Characteristic strength of 15 N/mm2 is recommended for concrete made with RNS and WWS of gravel A, while 11 and 14 N/mm2 are recommended for those of gravel B, respectively.

Green Lightweight Concrete Made from Natural Para Rubber Product

Para Rubber Seed Shell (PRSS) as a coarse aggregate and coated by vulcanization and mixing epoxy natural rubber (ENR) was investigated. Natural rubber latex (60% DRC) was applied in two stages. Firstly stage, synthetic natural latex (ENR-35) solution was coated on the first layer of PRSS. After that, PRSS was coated by vulcanization in second layer. Then, pre-wetting was performed before mixing or casting the concrete for 5 days. Finally, CPRSS (Coated Para Rubber Seed Shell) was produced. The CPRSS aggregate was cast as self consolidation concrete (SCC) with different ratios of ordinary Portland cement: sand: CPRSS for 0.8-1: 0.6-0.85: 0.04-0.12 by weight, respectively and constant water/binder ratio at 0.45 throughtout this study. The ENR-35 was also used about 5% of the water content. However, the concrete was wrapped with polyvinyl sheet to prevent moisture loss during setting and curing in ambient temperature (29°C, 84%RH) for 28 days. The fresh concrete to slump test, harden concrete with bulk density and compressive strength of whole formulations was carried out to determine. The test result A8 indicted that the most ingredient suitable mixture of SCC involed cement: sand: CPRSS of 1:0.94:0.046. The SCC contained the slump as 120 mm, bulk density about 1916 kg/m3 and compressive strength was 37 MPa. Its was met specification of structural lightweight concrete. This beneficiation of SCC is also product as the green innovation building in terms of construction materials and resources, leaving minimal environmental impact, and having energy saving and <em>eco-friendly materials</em>.

Fracture Properties and Microstructure of Concrete Made with Recycled Aggregate

This paper presents the results of the fracture properties and microstructure of recycled aggregate concrete (RAC) compared with those of natural aggregate concrete (NAC). Concrete specimens were fabricated and tested with the recycled coarse aggregate (RCA) replacing of 0%, 40%, 70% and 100%, respectively. The three-point bending beam method was used to measure the fracture properties of the concrete. SEM and X-CT were used to investigate the microstructure of the concrete. The RCA addition in the concrete caused a decrease in the fracture properties and loose microstructure.

Carbonation Coefficients from Concrete Made with High-Absorption Limestone Aggregate

Normal aggregates employed in concrete have absorption levels in the range of 0.2% to 4% for coarse aggregate and 0.2 to 2% for fine aggregate. However, some aggregates have absorption levels above these values. As the porosity of concrete is related to the porosity of both the cement paste and the aggregate and the carbonation rate is a function, among other things, of the porosity of the material, there is concern about the effect of this high porosity material in achieving good quality concrete from the durability point of view. Thus, the objective of this investigation was to study the carbonation rates of concrete specimens made with high-absorption limestone aggregate. Four different water/cement ratios were used, and cylindrical concrete specimens were exposed to accelerated carbonation. High porosity values were obtained for concrete specimens beyond the expected limits for durable concrete. However, carbonation coefficients related to normal quality concrete were obtained for the lowest water/cement ratio employed suggesting that durable concrete may be obtained with this material despite the high porosity.

Research on Performance Concrete Made with Slay-Fly Ash and Ground Limestone

Base on experimental studying, early strength and work performance of portland cement, slay cement and fly ash cement improves and enhances when added ground limestone into and the adding content is beyond 8% .The strength of concrete is better than ordinary concrete, early strength increases by 16.9% when added ground limestone into and the adding content is beyond 10%. By studying on experiment, the strength of concrete which has been added slay and fly ash into when added ground limestone into and the adding content is 10% improves more than strength of concrete that has only adds slay or fly ash into. The fluidity of concrete that has added slay and fly ash into when added ground limestone into and the adding content is 10% lose small, this character is good at concrete construction. This experiment provides help for us to select concrete additive admixture and make good use of industrial waste.

Experimental Study on the Splitting Tensile Strength of Recycled Concrete Made of Brick and Tile

By experimental, study on the elastic modulus and the splitting tensile strength together with the influence of the splitting tensile strength with different water-cement ratio, sand rate and water quantity , and the relational formula between the splitting tensile strength and the elastic modulus was summarized by regression analysis.

Creep Prediction Model for Concrete Made of Crushed Clay Bricks as Coarse Aggregate

A simple design office oriented empirical model containing only two parameters has been developed to predict creep behavior of concrete made of crushed clay bricks as coarse aggregate. For this, concrete samples having three different normal compressive strengths in the range of 18.9 up to 24.0 N/mm2 are first prepared and then tested for their creep deformation. For each of the samples, a hyperbolic equation is developed from their creep-time behavior. These equations are then combined and modified according to statistical norms to finally obtain a generalized equation. Comparison of creep strain obtained from this equation with that of experimental values show that the proposed model can closely predict creep in brick aggregate made concrete.

Experimental Study on Basic Mechanical Properties of Recycled Concrete Made of Brick and Tile

By experimental, study on the elastic modulus including the failure modes of Recycled Concrete made of Brick and Tile with the splitting tensile strength and the compressive strength, And the relational formula between the splitting tensile strength and the compressive strength was summarized from the results.

Concrete Made with Coarse Concrete Aggregate: Influence of Curing on Durability

This article will present the results of experiments conducted to determine the influence of different curing conditions on the durability of recycled aggregate concrete (RAC) made with coarse crushed concrete. Four different curing conditions that represent a wide range of quality control production were tested. The curing conditions tested ranged from uncontrolled outer environment conditions to standard defined temperature humidity curing conditions. The properties analyzed were shrinkage, water absorption by immersion and capillarity, carbonation, and chloride penetration. The article concludes that RAC is affected by curing conditions in much the same way as conventional concrete.

Chloride Diffusion in Blended Cement Concrete Made with Quartzite Recycled Aggregate

ABSTRACTUsing waste materials as aggregate for new concrete production is a growing tendency, because of several environmental problems. Recycled coarse aggregate (RCA) obtained from crushing waste concrete has lower density and greater absorption than natural aggregate, because of the higher porosity of the mortar attached to the RCA particles. Compressive strength level achieved in recycled concrete may be similar to that of conventional concrete. On the other hand, durable performance of recycled concrete is variable, and diverse evidence can be found in literature for different durability issues. In this paper, chloride ingress in conventional and recycled concrete, made with quartzite aggregate and blended Portland cement is evaluated when immersed in NaCl solution. Two strength levels (21 and 35 MPa) and two contents of RCA (25 and 75%), as substitute of natural quartzite aggregate, were considered. The chloride diffusion coefficient and the relationship between water-soluble chloride and bound chloride are analyzed.

Performance of Concrete Made with Manganese Slag

It is of great importance to innocuity, minimization and reutilization of manganese slag generated in manganese product by electric furnace process. In the paper, ordinary Portland cement was replaced partly by manganese slag to then evaluate manganese slag’ effect on mechanical performances of them. The experimental results obtained show that ordinary Portland cement added less than 30% by manganese slag was improved in mechanical performances and the cement concrete added less than 30% by manganese slag was not changed significantly. To lower economic cost and achieve enhanced mechanical performances, manganese slag can be substituted partly to cement concrete.

Study on Performance of High-Performance Concrete Made with Fly Ash and Polypropylene Fiber

High-performance concrete was made with fly ash and polypropylene fiber, the study shows that when fly ash content was 20% and polypropylene fiber was 0.6~1.2kg/m3, it had no significant influence on the workability of concrete, however the changes of 28d compressive strength and drying shrinkage of concrete are within 10%, but it can reduce brittle and improve toughness, and impact resistance of concrete is improved obviously, when polypropylene fiber content was 0.9kg/m3, it can improve over three times.

Study on Performance of Concrete Made from Sewage Sludge Ceramsite

In this paper, using sewage sludge carried out to manufacture high performance ceramsite. At the same time, the performance of concrete made from sewage sludge ceramsite was analyzed. The results show that the ceramist is mainly composed of cristobalite and mullet, and has dense enamel structure on surface and honeycomb closed fine porous structure in internal. Too large ceramsite size can cause concrete strength decrease, poor stability and workability; mineral admixtures make strength and workability of ceramsite concrete improve, but excessive addition could reduce concrete strength particularly in the early stage, so there is a reasonable dosage; ceramsite concrete strength is increased with the decrease of water-cement ratio, the increase of strength is not obvious when water-cement ratio reduced to a certain extent; increasing sand-ratio can improve concrete strength, but have adverse impact on the workability of fresh concrete.

A Generalized Abrams’ Law for Concrete Made with Natural and Recycled Aggregate

A Generalized Abrams’ Law for Concrete Made with Natural and Recycled Aggregate

Release of Heavy Metals from Concrete Made with Cement from Cement Kiln Co-Processing of Hazardous Wastes in Pavement Scenarios

Abstract Environmental safety assessments of products using cement from co-processing of hazardous wastes in cement kilns and formulation of criteria for pollution control of the cement products are necessary in Chinese environmental management departments. This article discusses the release of heavy metals from concrete using cement from the co-processing of hazardous wastes in cement kilns. The leaching test was based on typical applications of concrete in China. Total amount of heavy metals are much greater than leachability, and the ratio of total amount to leachability was dependent on the type of heavy metal. A good linear correlation between total amount and leachability of Cd was found (R2 is 0.994), but this was not the case for Cr, As, and Pb. pH influenced the release of heavy metals significantly, and the influences were related to the kinds of heavy metals. Diffusion control was the major release mechanism of Cr and Cd in concrete and the release curves fit very well the standard line with a ...

Strength and Durability of Concrete Made with Electric Steelmaking Slag

Strength and Durability of Concrete Made with Electric Steelmaking Slag

Mechanical Behavior of Structural Concrete Made with Recycled Aggregates from Tunnel Excavation

The results of an experimental study concerning the behavior of concretes made with recycled aggregates under repeated mechanical and thermal actions are presented. A comparison with the performances achieved by similar concretes made with traditional aggregates in the same working conditions eventually made it possible to estimate the actual quality and durability of the recycled concretes examined and identify possible limitations in their use. The laboratory protocol here adopted is suggested as a practical experimental procedure to test hardened concretes and pre-qualify their performances with respect to compressive actions and thermal solicitations.

The Quality of Concrete Made with Typical Benin City Silty Sand

The purpose of this study is to carry out tests on concrete made with a typical Benin City silty sand and determine the major concrete quality indicators such as pulse velocity, water/cement ratio and compressive strength in order to justify the continued utilization of such sands in concrete production in and around Benin City. To do this, concrete made with the selected sand were designed using DOE mix design method and test cubes were cast in three batches. Two cubes were cast for each of the sixteen consecutive tests carried out and averages taken for each design grade strength of 10,20,30,40 and 50N/mm2. Also, pulse velocity and rebound hammer tests were carried out on the cubes before testing the cubes destructively. The results show that concrete produced with the Benin City silty sands are of good quality in all respect but generally characterized by low 28th day – characteristic strength. The sands should therefore be used in construction provided that the mean strength aimed at during design is sufficiently higher than the characteristic strength by the strength margin (ks) from structural point of view to enable every part of the structure have adequate strength.