Performance Of Concrete Mixes Research Articles

Improving Quality of High Performance Concrete by Cavitation Treatment of the Raw Materials

The packing of fine aggregate affects the properties of HPC. The denser is fine aggregate packing the better are the workability, compressive strength and watertightness, and with that the frost and chemical resistances under sufficient paste content upplementary cementing materials such as silica fume has predominantly used for HPC due to it improves the packing of the concrete mix and activates the pozzolanic reaction. But agglomerates can be formed in this fine aggregate mix and therefore the packing of the mix is not improved, chemical reaction is hindered and the use of this aggregate may worsen the concrete properties instead of improving them.The effect of cavitation treatment on silica fume and cement is investigated in this work. Due to cavitation treatment, the agglomerate of silica fume and cement collapses into nano- and micro-particles and uniforms dispersion of small dispersed particles in liquid medium. Granulometric composition of silica fume slurry before and after cavitation treatment was determined.High performance concrete mixes with designed packing including micro- and nano-size fillers were elaborated. Fresh and hardened concrete were tested and such properties as cone flow, watertightness, water absorption and compressive strength were defined for control and experimental mixes. The influence of cavitation treatment of small dispersed raw materials on the compressive strength properties of produced concrete has been evaluated.

해상교량 주탑용 고성능 콘크리트의 기준재령 염소이온 확산계수

기준재령 염소이온 확산계수를 측정하기 위하여 고성능 콘크리트 배합을 선정하고 공시체를 제작하였다. 배합은 해양환경에 건설되는 교량에 적합하도록 선정되었으며 배합설계 변수는 결합재 종류, 물-결합재비, 광물질 혼화재치환율, 잔골재 종류, 고강도 및 고유동성을 얻기 위한 화학 혼화제 종류, 목표 슬럼프 또는 슬럼프 플로우이다. 시험결과로부터 기준재령 염소이온 확산계수는 결합재 종류와 그 치환율에 따라 크게 다름을 확인하고, 결합재 종류와 치환율을 고려한 기준재령 확산계수 모델을 개발하였다. 개발된 모델의 확산계수를 기존 모델의 확산계수 및 추가 확산계수 측정시험 결과 비교하여 개발된 모델의 타당성을 확인하였다.

Development of Mix Proportion for High-Performance Concrete Using Locally Available Ingredients Based on Compressive Strength and Durability

Keywords: High Performance Concrete, mix proportions, compressive strength , and durability Abstract. The use of concrete materials to date, remain a key ingredient in such construction work on the construction of building, bridges and infrastructure. One indicator is the increased production of readymix concrete which is nearly 16 billion tons in 2010. But the increased used of concrete, apparently bring the impact of environmental damage. This is due to the fact that production of raw materials contributes greatly to CO2 in the air. One effort to reduce such impact is to use of high performance concretes. Mix proportion of High Performance Concrete are strongly determined by the quality and availablity of local materials. The implications of research result from other countries can‘t be directly used. Therefore is need to the research on development of High Performance Concrete mix using locally available materials. In this research the mix proportions for f’c : 60 and 80 MPa are developed using local materials that are commonly used by readymix producers. The high Performance Concrete is developed based on compressive strength and durability. The result is expected to be applied to readymix industry particularly for construction use in Indonesia.

A new predictive model for compressive strength of HPC using gene expression programming

In this study, gene expression programming (GEP) is utilized to derive a new model for the prediction of compressive strength of high performance concrete (HPC) mixes. The model is developed using a comprehensive database obtained from the literature. The validity of the proposed model is verified by applying it to estimate the compressive strength of a portion of test results that are not included in the analysis. Linear and nonlinear least squares regression analyses are performed to benchmark the GEP model. Contributions of the parameters affecting the compressive strength are evaluated through a sensitivity analysis. GEP is found to be an effective method for evaluating the compressive strength of HPC mixes. The prediction performance of the optimal GEP model is better than the regression models.

Development of an Economical High Early Strength Concrete Mix for Paving of Provincial Roads in Sri Lanka

Rigid pavement construction has a long history. Ready mixed or site mixed or site mixed concrete is used for rigid pavement construction. However, conventional concrete mixtures require more than 7 days to gain adequate strength to allow for traffic. Development of high early strength concrete would be a solution to allow traffic within a reasonable time. However, use of high cement content in early strength concrete induces distress in the pavements and would not be an economical mix. A high performance concrete mix was developed for rigid pavement construction using a low cost admixture with available material in Sri Lanka. Study has shown that 3% of commercial grade CaCl2 can be used as an accelerator to obtain required compressive strength and the flexural strength of concrete in 12 hours. Strength gain was verified by the maturity test conducted for a slab placed under field condition. Slab temperature was also measured with time and found temperature rise due to hydration was insignificant. Using the mix proportion developed, concrete roads can be allowed for traffic in 12 hours and can also be used for repair works of the existing roads. Life cycle cost analysis was performed taking into account the construction cost, maintence cost and the user cost. The study has shown that there is 26% saving by using high early strength concrete developed in this study.

Study on Improving Overall Calculation Method of Mix Design Method for Fly Ash HPC

Applying to high performance concrete mix design, overall calculation method can fully quantify the various components of concrete. While the application of overall calculation is very wide, its applicability has weaken with the increase of fly ash. In particular, overall calculation is not applied to high volume fly ash concrete. The reason is simplely considered fly ash cement as a simple alternative to cement when designing of concrete mix, and then following the water-cement ratio strength formula to design concrete mix, neglecting the differences of contribution to concrete strength between fly ash and cement. To solve these problems, this paper considers the fly ash as a separate component of concrete, and re-establishes two variables strength formula based on water-cement ratio and fly ash dosage. On the basis of the generally applicable volume model of concrete, overall calculation is re-derived, then used to directly design high performance concrete mix ratio. Improved overall calculation method is more widely ,more scientific and more reasonable, and will have a far-reaching influence on the application of high volume fly ash high performance concrete.

Modeling of compressive strength of HPC mixes using a combined algorithm of genetic programming and orthogonal least squares

In this study, a hybrid search algorithm combining genetic programming with orthogonal least squares (GP/OLS) is utilized to generate prediction models for compressive strength of high performance concrete (HPC) mixes. The GP/OLS models are developed based on a comprehensive database containing 1133 experimental test results obtained from previously published papers. A multiple least squares regression (LSR) analysis is performed to benchmark the GP/OLS models. A subsequent parametric study is carried out to verify the validity of the models. The results indicate that the proposed models are effectively capable of evaluating the compressive strength of HPC mixes. The derived formulas are very simple, straightforward and provide an analysis tool accessible to practicing engineers.

Prediction of the Compressive Strength of High Performance Concrete Mix using Tree Based Modeling

is the safest and sustainable construction material which is most widely used in the world as it provides superior fire resistance, gains strength over time and gives an extremely long service life. Its annual consumption is estimated between 21 and 31 billion tones. Designing a concrete mix involves the process of selecting suitable ingredients of concrete and determining their relative amounts with the objective of producing a concrete of the required, strength, durability, and workability as economically as possible. According to the National Council for Cement and Building Materials (NCBM), New Delhi, the compressive strength of concrete is governed generally, by the water-cement ratio. The mineral admixtures like fly ash, ground granulated blast furnace, silica fume and fine aggregates also influence it. The main purpose of this paper is to predict the compressive strength of the high performance concrete by using classification algorithms like Multilayer Perceptron, M5P Tree models and Linear Regression. The result from this study suggests that tree based models perform remarkably well in predicting the compressive strength of the concrete mix.

Effect of Steam Curing on Concrete Piles with Silica Fume

Silica fume is a common addition to high performance concrete mix designs. The use of silica fume in concrete leads to increased water demand. For this reason, Florida Department of Transportation (FDOT) allows only a 72-hour continuous moist cure process for concrete containing silica fume. Accelerated curing has been shown to be effective in producing high-performance characteristics at early ages in silica-fume concrete. However, the heat greatly increases the moisture loss from exposed surfaces, which may cause shrinkage problems. An experimental study was undertaken to determine the feasibility of steam curing of FDOT concrete with silica fume in order to reduce precast turnaround time. Various steam curing durations were utilized with full-scale precast prestressed pile specimens. The concrete compressive strength and shrinkage were determined for various durations of steam curing. Results indicate that steam cured silica fume concrete met all FDOT requirements for the 12, 18 and 24 hours of curing periods. No shrinkage cracking was observed in any samples up to one year age. It was recommended that FDOT allow the 12 hour steam curing for concrete with silica fume.

Design of High Performance Concrete Mixes Through Particle Swarm Optimization

Design of High Performance Concrete Mixes Through Particle Swarm Optimization

Elitist Genetic Algorithm Models: Optimization of High Performance Concrete Mixes

This article elaborates the development of elitist Genetic Algorithm (GA) models for the optimization of high volume fly ash concrete (HVFAC) mix. The model consists of two stages. In the first stage, a huge database of 350 mix designs garnered through standard research publications were statstistically analyzed to elicit upper and lower bounds of certain range constraints and rational ratio constraints of functional parameters. In the second stage, elitist GA is applied to find the quantities of cement, fly ash, and water for maximized strength of the mix. Optimal mix proportions of these important ingredients are computed corresponding to five ranges of 28 day' strength by augmenting the algorithm with appropriate constraint ranges obtained in the first stage. The optimized proportions of ingredients in all the five cases are encouraging and corroborate very well with the experimental results. The outcome of this work is useful in reducing the number of trial mixtures with desired properties in the field tests.

Early-age stress–crack opening relationships for high performance concrete

Stress–crack opening relationships for concrete in early age have been determined for two high performance concrete mixes with water to cementitious materials ratios of 0.307 and 0.48. The wedge splitting test setup was used experimentally and the cracked non-linear hinge model based on the fictitious crack model was applied for the interpretation of the results. A newly developed inverse analysis algorithm was utilized for the extraction of the stress–crack opening relationships. Experiments were conducted at 8, 10, 13, 17, 22, 28, 48, 168 h (7 days) and 672 h (28 days). At the same ages, split tests were carried out. Fracture energy, Gf, was found to increase with age, while the characteristic length, lch, was found to decrease.

Performance of concrete mixes with OPC?PFA blends

This paper describes a comprehensive programme of testing for strength, durability (sorptivity, carbonation, drying shrinkage, sulphate attack and chloride ingress) and fresh-state properties (slump, slump loss, setting time, temperature rise and plastic shrinkage) of grade 25 and 35 concretes, where the ordinary Portland cement (OPC) binder was replaced with 15% and 25% of pulverised fuel ash (PFA). Three types of OPC–PFA mixes, designated ‘safe’, ‘workable’ and ‘economical’, were investigated. In general, the results from the PFA mixes were similar to or better than the OPC control mixes. The charge passed in the indirect chloride ion penetration test and the heat of hydration temperature rise were considerably reduced in the PFA mixes. They were however more susceptible to plastic shrinkage cracking. It was also found that the strength ratio between PFA mixes and OPC controls was slightly greater at 3 days than at 7 days, after which this ratio increased again, as expected.

Performance of concrete mixes with OPC–PFA blends

This paper describes a comprehensive programme of testing for strength, durability (sorptivity, carbonation, drying shrinkage, sulphate attack and chloride ingress) and fresh-state properties (slump, slump loss, setting time, temperature rise and plastic shrinkage) of grade 25 and 35 concretes, where the ordinary Portland cement (OPC) binder was replaced with 15% and 25% of pulverised fuel ash (PFA). Three types of OPC–PFA mixes, designated ‘safe’, ‘workable’ and ‘economical’, were investigated. In general, the results from the PFA mixes were similar to or better than the OPC control mixes. The charge passed in the indirect chloride ion penetration test and the heat of hydration temperature rise were considerably reduced in the PFA mixes. They were however more susceptible to plastic shrinkage cracking. It was also found that the strength ratio between PFA mixes and OPC controls was slightly greater at 3 days than at 7 days, after which this ratio increased again, as expected.

Effect of coarse aggregate on elastic modulus and compressive strength of high performance concrete

A set of high performance concrete mixes, of low water cement ratio and fixed mortar composition, containing six different types of aggregates of constant volume fraction, has been used to check moduli of elasticity at 7, 28 and 91 days. The results have shown that, apart from the aggregates of very low and very high modulus, concrete modulus at 28 days can be predicted quite well by well-known models. Increase in modulus thereafter is slight. Cube strength (about 90 N/mm 2 at 28 days with normal aggregates) is drastically reduced, as expected, by the weaker aggregates and is also reduced (by about 9%) by the stiffer (steel) aggregates.