Compressive Strength Research Articles

Monitoring of Strength Development in Portland Cement Concrete With High Fly-Ash Content at the FAA’s National Airport Pavement Test Facility

Construction Cycle 2 (CC2) at the FAA’s National Airport Pavement Test Facility (NAPTF) included construction of three concrete test items MRC, MRG, and MRS on three different support conditions (crushed-stone subbase, slab on grade, and econocrete stabilized subbase). All three test items were constructed on a CBR 7-8 subgrade. The existing econocrete subbase (P-306) from CC1 test item MRS was used for CC2 MRS. Concrete was placed in the test items using a concrete pump into fully formed 15 ft. (4.57 m) by 15 ft. (4.57 m) slabs. Test results are presented and discussed in this paper. Test results include concrete placement details (slump, air content, concrete temperature), compressive strengths, flexural strengths, elastic modulus from free-free resonance tests on concrete beams and cylinders, portable seismic pavement analyzer (PSPA) tests, and strength results from sawed beams and cored cylinders taken from untrafficked test slabs. Concrete specimens included both laboratory cured and field cured specimens. PSPA tests were performed on the test item slabs at the age of one day and on regular intervals after that, coinciding with the laboratory testing of beams and cylinders. The test results showed good correlation between elastic modulus (from free-free resonance and PSPA tests) and strength values (compressive and flexural strengths) and demonstrated the application potential of a testing device such as PSPA for assessing the early-age strength of concrete.

Experimental Study of Carbonation and Chloride Resistance of Self-Compacting Concretes with a High Content of Fly Ash and Metakaolin, with and Without Hydrated Lime

The durability of reinforced concrete is associated with several factors that can trigger the corrosion of reinforcement bars. Among these factors, the most significant are chloride-ion attack and carbonation. This study evaluated, through accelerated testing, self-compacting concretes (SCCs) with reduced cement content in binary, ternary, and quaternary mixtures using high-early-strength Portland cement, fly ash (FA), metakaolin (MK), and hydrated lime (HL). These systems are proposed to address the slow compressive strength gains at 28 days in concretes with high fly ash content and to minimise the effects of carbonation in concretes with high levels of mineral additives. Laboratory tests were conducted to measure chloride-ion migration in a non-steady-state system, accelerated carbonation in a controlled chamber, electrical resistivity, void indices, and compressive strength. Based on the results obtained, it was found that the combined use of MK, FA, and HL was effective in reducing cement consumption to extreme levels, such as 120 and 150 kg/m3, while still achieving durability indices superior to those of SCCs with cement consumption of 500 kg/m3.

Finite Element Analysis of PCCP Curling and Roughness

Smoothness specifications for newly built Portland Cement Concrete Pavements (PCCP) in Kansas have evolved over the last two decades through applications and a number of revisions. However, some PCCP sections built under current specifications in the smoothness bonus range experience rapid loss of smoothness with time. Sometimes this happens even before the sections are opened to traffic. It is believed that this loss results from curling due to the temperature differential between the pavement top and bottom surfaces. In this study, threedimensional simulation of curling of PCCP has been presented using a finite element (FE) software, ANSYS. A number of FE models were built to simulate several newly built PCCP sections in Kansas. The sections were modeled as three-layer systems with cement-treated base and lime-treated subgrade. Layer materials were modeled as linear elastic and the properties were obtained from the tests conducted during construction. Pavement layers and steel dowel bars were modeled using 3- dimensional solid (brick) elements. The complex interaction of the slab with the dowel bars was modeled as a contact problem. Regression models were developed for the curling deflection and International Roughness Index (IRI), a roughness statistics resulting from the curled profiles, based on different simulation parameters. The results obtained from the simulations show that the curling deflection and IRI calculated from the deflected slab profiles are affected by the slab thickness, compressive strengths of the concrete slab and base layers, and the temperature differential between the pavement top and bottom surfaces. Both curling deflection and IRI increase with an increase in temperature differential and compressive strength of the stabilized base layer. Higher slab thickness and concrete compressive strength would result in lower curling deflection and IRI values.

Thin whitetopping overlay over a deformed asphalt pavement of a highly trafficked urban intersection

The construction of thin or ultra-thin whitetoppings is considered as an up-to-date rehabilitation technology for flexible pavement structures with repeatedly deformed pavement surface. The experiences on the first use of this technique in Hungary is presented briefly. A highly trafficked urban intersection with traffic signal was the site of the test section. The laboratory investigation of cored samples taken from the deformed pavement structure was followed by cement concrete mix design by KTIinstitute. Four previous trials were carried out in May-July 2007. The experience gained in these trials was utilised in the actual execution of the experimental section in October 2007. The deteriorated asphalt layers were milled in 120 mm depth. A 85 m-long whitetopping in 120 mm thickness was placed using manual paving technique. 1.75x1.75 m slabs were cut in the thin cement concrete layer without joint filler and dowels. The main quality parameters measured of the fresh cement concrete mixture were: slump, air bubble content, density, temperature, optimum time for curing plastic covers, strength. The density, compressive strength, splitting tensile strength, flexural strength, water permeability and surface texture depth were measured on the hardened concrete. After 6 months (severe winter), the section is in excellent condition, no damage can be seen. Several new thin whitetopping sections are planned in Hungary for 2008.

Analysis of Blended Concrete using Aerating Agent with Geopolymer

Geo polymer is considered as the third-generation cement after lime and ordinary Portland cement. Light weight geo polymer concrete is produced when for foaming agent is added to slurry, the function of foam is to create an air voids in fly ash–based geo polymer slurry. In this investigation of Light weight geo polymer concrete mixtures are produced foaming agent like aluminum powder with 0.5%,1.0%, 1.5% and 2.0% with Geo Polymer concrete and 15 Cube specimens are prepared and tested for mixtures of M30 mix as used in conventional concrete for Geo Polymer concrete ,then their physical (Density and workability) as well as specific structural (Compressive Strength) properties were investigated, Specific Strength and Percentage Strength gain for aerated concrete is compared with normal weight concrete and the results are reported. Key words- Light-weight concrete, Geo polymer concrete mass, Geo Polymer, strength –properties, foaming agent, density, target strength, fly ash.

Mechanical and microscopic characterization of expansive soils modified by water-soluble polymers

With the advancement of ecological and environmental protection construction, the research on the modification of expansive soil using environmentally friendly polymers can make up for the harm to the ecological environment caused by traditional modification. Mechanical and microscopic properties of modified expansive soils were analyzed through indoor tests. The results showed that the liquid limit and plasticity index decreased by 52.14% and 77.36%, respectively, and the plastic limit increased by 20.83%. Maximum dry density decreased by 5.11% and optimum moisture content increased by 28.47%. The compressive and shear strength increases and then decreases with the increase of dosage, and the strength reaches the maximum when the dosage is 4%, and the vertical and lateral deformation of the specimen is the smallest. Modified soil swelling was reduced by 54.57% and swelling forces were reduced by 15–57%. The modified soil cracks developed slowly and the width of the cracks was reduced by 61.68% after the modification. Microscopy showed that no new minerals were generated after doping modifier, while hydrophilic minerals were reduced by 43.14%, and the gel film formed by hydration made the pores smaller and the structure tighter by filling and wrapping on the surface of the particles.

Experimental Study on Properties of Portland Cement Concrete Containing Recycled Asphalt Pavements

Although recycled asphalt pavement (RAP) are widely used in the construction of new, and reconstruction of old, hot mix asphalt (HMA) pavements, little research has been done to examine the potential of incorporating RAP into Portland cement concrete to replace virgin aggregate. Because RAP consists of aggregates coated by asphalt cement, the toughness of concrete made with RAP could be improved. In this paper, the mechanical properties of portland cement concrete containing RAP were investigated through laboratory experiments. Two types of RAP (coarse and fine RAP) materials were used to replace the equal amount of virgin coarse and/or fine aggregate. Silica fume and high-range water reducing agent (HRWRA) were also added into concrete mixtures to minimize the strength loss due to the incorporation of RAP. A total of 17 concrete batches were cast and tested for compressive and split tensile strengths, static compressive modulus of elasticity, and toughness index in accordance with ASTM standards. Test results indicated that there was a systematic reduction in the strengths and elastic modulus as well as an increase in the toughness index with the increase in RAP content. While the addition of HRWRA into the matrix improved the mechanical properties of concretes containing RAP, addition of silica fume unexpectedly did not.

Roller-Compacted Concrete Pavement, An Industry Perspective

This paper presents a summary of findings and experiences in implementing Roller- Compacted Concrete Pavement (“RCC Pavement”) at industrial distribution facilities. The author’s experiences in RCC Pavement involved defining and taking complete responsibility from concept to completion, including but not limited to, material selection, mixture design, structural design, production, transportation, placement and curing. Using ten-plus years of experience and incorporating pertinent research findings, processes and tests lead to the development of Quality Assurance (“QA”) Processes and Quality Control (“QC”) tests/observations. Continuous improvement has been made on developing a QC program. The author’s experiences involved the use of RCC Pavement as a finished surface and dictated a high performance RCC Pavement (compressive and flexural strength as high as 40 MPa and 5MPa, respectively after only 7 days); therefore, all placement utilized an ABG paver and vibrating screed with dual tamping bars to obtain high density RCC Pavement while minimizing roller displacement and maximizing smoothness and riding characteristics of the final RCC Pavement surface. Size of the projects has limited these experiences to production of RCC Pavement through the use of either a wetbatch concrete plant or a dry-batch concrete plan in conjunction with a horizontal shaft mixer.

Zeta Potential Change and curing effects on Shield Muck solidified by Metal Ion Complex Catalysis

Using potentiometric testing, we investigated the zeta potential of shield muck curing materials’ particle surfaces, varying the concentration of metal ion complex. We analyzed the microscopic characteristics of shield muck curing products by using the electron microscopy, revealing the impact of metal ion complex on curing. Results showed that the metal ion complex significantly reduces the surface zeta potential of shield muck and conventional curing materials, with cement showing the most substantial effect, followed by shield muck, calcium carbonate, and calcium sulfate. The concentration of metal ion complex negatively correlates with the zeta potential within a range of 0 to 100 mmol/L. Comparing shield muck cured for 7 and 28 days, with and without metal ion complexes, indicated that metal ion complexes accelerate crystalline product formation, increasing the compressive strength of shield cinder cured products by over 35%. Fitted curves and empirical parameter equations of zeta potential and metal ion complex concentration align with experimental results. This study provides a reference for the efficient treatment and sustainable utilization of shield slag soil, holding significant practical engineering value.

A safe highway driving surface using an open graded concrete

The use of open graded asphalt wearing courses for highway pavements is established technology but the opportunities to use a similar cementitious based surface type for concrete pavements has been limited by material technology and costs. Research work in Australia using new generation concrete admixtures and placing techniques has allowed the development of a stiff open graded concrete material which is expected to meet the same durability requirements as standard concrete used for roads. Open graded surface textures absorb vehicle noise emissions and minimise water film build up during rain events, thus resulting in quieter and safer driving conditions. In addition, experience has shown that high void contents at the surface assist in reducing water spray generation and glare reflection. This paper details the laboratory mix design test results and three field trials using hand placing techniques to define the limits of a wet on wet construction process. The concrete developed in the trials has high compressive strength with air voids in the range of 20 to 30%. The next stage in the development of the open graded concrete surfacing is in the use of mechanised placing techniques to make the process cost competitive to other asphalt alternatives and yet meet similar durability requirements to those currently expected in concrete road surfaces over a 40 year design period.

RF Optimizer Model for Predicting Compressive Strength of Recycled Concrete

RF Optimizer Model for Predicting Compressive Strength of Recycled Concrete

Interpretable Machine Learning Method for Compressive Strength Prediction and Analysis of Pure Fly Ash-based Geopolymer Concrete

Interpretable Machine Learning Method for Compressive Strength Prediction and Analysis of Pure Fly Ash-based Geopolymer Concrete

MIXTURE RATIO DESIGN METHOD FOR POROUS CONCRETE PERMEABLE BASE

As a new kind of material for permeable base, mixture ratio design of porous concrete should ensure both the porosity and the mechanical strength. Based on Talbol Formula and foreign experiences, four kinds of gradation of porous concrete are designed and effective particle size and uniform coefficient are taken as the effective descriptive targets of aggregate gradation. Three factors of cement dosage, water cement ratio and aggregate gradation are considered in an orthogonality test with four levels adopted in every factor. Through variance analysis of the tests results, it can be drawn that when confidence probability is 95%, the factors that evidently affect 7d compressive strength are gradation and cement aggregate ratio, and the factors evidently affect effective porosity are gradation, cement aggregate ratio and water cement ratio. While when confidence probability is 90%, gradation, cement dose and water cement ratio all have evident influence on 7d compressive strength and effective porosity. Based on the test results, a series of regression relationships of 7d compressive strength and effective porosity of porous concrete are derived. Finally, the empirical equation method of mixture ratio design for porous concrete is proposed.

Investigating and Evaluating Novel Fly Ash-Based Proppant Compressive Strength Under Various Environmental Conditions

As hydraulic fracturing becomes increasingly prevalent in the oil and gas industry, there is a growing need to develop more cost-effective and sustainable technologies, particularly concerning the materials used. Proppants play a vital role in hydraulic fracturing by ensuring that fractures remain conductive and can withstand the pressure exerted by the surrounding strata. One key parameter for evaluating proppants is their compressive strength, especially under harsh environmental conditions. High-strength proppants, such as those made from ceramics or bauxite, are typically expensive due to the materials and complex manufacturing processes involved. In contrast, fly ash, a byproduct of coal-fired power plants, offers a more affordable and environmentally sustainable alternative for proppant production. This study focuses on the development and evaluation of a fly ash-based proppant, exposed to harsh conditions including high temperature and pressure, as well as acidic, alkaline, saline, and crude oil environments. The fly ash was activated using an alkaline solution, which served as a chemical binder for the proppant. After exposure to these conditions, the compressive strength of the fly ash-based proppants was compared to control samples. The results showed that the proppants’ compressive strength was largely unaffected by the harsh environments, particularly for the B20W25 mix design. However, while the fly ash-based proppants performed well under stress, their compressive strength was still lower than that of conventional proppants used in the industry. The B20W25 sample demonstrated a compressive strength of 1181.19 psi (8.1 MPa), which, although resilient, remains below industry standards.

Effect of Active MgO on Compensated Drying Shrinkage and Mechanical Properties of Alkali-Activated Fly Ash–Slag Materials

The influences of MgO activity and its content on the mechanical properties, drying shrinkage compensation, pore structure, and microstructure of alkali-activated fly ash–slag materials were investigated. Active MgO effectively compensated for the alkali-activated materials’ (AAMs’) drying shrinkage. The drying shrinkage increased rapidly with the increase in curing age and stabilized after 28 d. Within a certain range, the material’s drying shrinkage was inversely proportional to the content of active MgO. The higher the activity of MgO, the lower the drying shrinkage of the AAMs under the same MgO content. The drying shrinkage values of the test groups with 9% R-MgO, M-MgO, and S-MgO at 90 d were 2444 με, 2306 με, and 2156 με, respectively. In the early stage of hydration, the addition of S-MgO reduced the compressive strength. As the content of M-MgO increased, the compressive strength first increased and then decreased, reaching a maximum of 72.28 MPa at an M-MgO content of 9%. The experimental group with 9% M-MgO exhibited higher compressive and flexural strengths than those with 9% S-MgO and R-MgO, demonstrating better mechanical properties. The results of this study provide an important theoretical basis and data support for the optimal application of MgO in AAMs. MgO expansion agents have great application potential in low-carbon buildings and durable materials. Further research on their adaptability in complex environments will promote their development for engineering and provide innovative support for green buildings.

Investigation of the optimum calcination temperature for water treatment plant sludge to develop a sustainable alkali activated concrete

Nowadays, Egypt is treating the Nile River Water to produce drinking water, and this process generates large amounts of waste, around 635 million m3 annually, which is called water treatment plant sludge (WTPS). This WTPS cost the government around 30 million US dollars to return it back to the Nile River in addition to negatively affecting the environment. Therefore, there is an urgent need to find environmentally friendly alternatives that reduce the impact of such an issue. This paper focuses on treating WTPS by drying, grinding and calcining to develop it as an alternative binder for use in alkali-activated concrete. This approach would not only provide green construction material but also reveal an environmental disposal route for the sludge produced in Egypt or in any country has the same issue. The treatment methodology used in this study was based on finding the optimum calcination temperature regime for WTPS after drying and grinding. Fifteen specimens of WTPS powder were used to investigate the optimum calcination temperature and duration by applying different temperatures ranging from 500 °C to 800 °C for various exposure durations of 30, 60 and 90 min. XRD and Chapelle tests were employed to chemically investigate the efficiency of the obtained calcined WTPS specimens, while strength activity index and compressive strength tests were used to mechanically verify the findings of the chemical tests. The results indicated that the calcination regime, which involved applying a maximum temperature of 650 °C for 90 min, achieved the best chemical characteristics and a strength activity index of 145%. Moreover, this regime resulted in a compressive strength of 21 MPa when WTPS powder was used as a precursor in alkali-activated concrete. Additionally, this paper presented a brief comparison of the production cost and energy consumption between cement and WTPS. The comparison demonstrated the efficiency of using WTPS as a replacement for cement, showing that the production of WTPS costs 50% less and consumes 92% less energy than cement.

Biomechanical and biodegradation performance of CSA-CSF reinforced cementitious composites: A bio-inspired approach

This study investigates the mechanical, biodegradation, and microstructural performance of cementitious composites reinforced with Corn Straw Ash (CSA) and Corn Straw Fiber (CSF) for applications in bio-inspired materials and sustainable engineering. CSA, a pozzolanic material, enhances matrix densification, while CSF provides crack-bridging and toughness improvement. Dynamic mechanical testing under cyclic loading demonstrated that CSA-CSF composites exhibit superior fatigue resistance, retaining 85% of their initial compressive strength after 1000 cycles. Biodegradation studies in simulated body fluid (SBF) and acidic environments revealed that the composites maintain 75% compressive strength in SBF over 28 days, highlighting their potential for bioactive scaffolds. Scanning electron microscopy (SEM) and quantitative porosity analysis showed that CSA-derived Calcium Silicate Hydrate (C-S-H) gel effectively filled voids, while CSF enhanced fiber-matrix bonding, mimicking the hierarchical structure of biological systems. The results emphasize the dual benefits of CSA-CSF composites in dynamic environments and their alignment with sustainable and bio-inspired design principles. This research provides insights into the development of materials for biomechanical applications, including tissue engineering scaffolds and earthquake-resistant structures.

Effect of High Percentages of Coated Recycled Aggregates on the Flexural Behavior of Reinforced Concrete Beams

Currently, the use of recycled aggregates (RA) in new concrete is allowed by several international regulations, although their replacement is limited to low percentages of the coarse fraction. In order to increase the percentage of RA, several authors have studied different processes to improve the microstructure of its surface. Therefore, it is necessary to analyze whether the current standards simulate the structural behavior of concretes with high percentages of RA. For this purpose, beams with 0%, 50% and 100% RA replacement coated with recycled binder paste (RBP) were made and their behavior was compared with the equations of the Eurocode 2 and ACI 318-19 code. As a result, we found that when 100% coated RA was used, the reduction in compressive strength was only 12.73%, with similar cracking patterns observed in RA beams across all series. In addition, the load capacity of the beams with RA was higher than the theoretical values provided by the codes. Finally, the experimental critical deflection was higher than that calculated by the code equations. Thus, it is recommended that these higher deflections be taken into account at the time of design.

Possibility investigation of phase change material-impregnated and surface coated cork as an aggregate for building envelope application

ABSTRACT PCM is a valuable construction material due to its energy efficiency, but leakage during phase changes poses challenges. This study developed a cork energy storage aggregate (CESA) by vacuum impregnating cork with phase change material (PCM) and coating it with polymer and silica fume to address leakage. Experiments confirmed the suitability of CESA as a building material, demonstrating its compressive strength. Thermal analysis via differential scanning calorimetry showed a decrease in enthalpy after PCM impregnation, with CESA with parafol-20Z displaying an enthalpy of 88 J/g compared to the 193.5 J/g of PCM. Despite the reduced enthalpy, CESA aggregates delayed temperature rise effectively in energy storage tests. CESA with paraffin wax showed a 1.48 times temperature-increasing time lag, and CESA with parafol-20Z showed a 1.78 times time lag. These results meant that CESA showed a potential for energy-saving performance when this technology is applied to buildings. Laboratory experiments under varying ambient temperatures further confirmed the significant of CESA heat storage capacity. These findings highlight the importance of selecting PCM based on external temperature and melting point for optimal energy savings, demonstrating the potential of CESA to reduce energy consumption in construction.

Experimental and analytical study on axial behaviour of square corrugated concrete filled single and double skin tube stub columns

Concrete-filled double-skin steel tubular (CFDST) columns have become widely utilized in building construction and bridges, thanks to their exceptional structural capabilities. Therefore, this study investigates the axial compressive behavior of square CFDST columns. The study aims to explore the influence of external and internal plate shapes (flat or corrugated plates) and different widths of internal steel tubes on the axial compressive behavior. The effects of varying internal widths of the internal steel tube (60 mm, 116 mm, and 160 mm) on the performance of CFDST columns were examined. Additionally, the study compared the performance of concrete-filled steel tubular (CFST) and CFDST columns with external flat or corrugated plates. The findings indicated that incorporating internal corrugated plates notably improved both the load-carrying capacity and ductility of the specimens. Notably, CFDST columns featuring corrugated internal plates (116 mm width) exhibited strength enhancements of 25.3% and 7.4% compared to internal widths of 160 mm and 60 mm, respectively. Furthermore, the study proposed two machine-learning models, namely Artificial Neural Network (ANN) and Gaussian Process Regression (GPR), to estimate the ultimate compressive strength of square CFDST columns. The findings indicated that the GPR model outperformed the ANN model in predicting the bearing capacity of square CFDST columns. Additionally, the Shapley Additive Explanation technique was employed for feature analysis. The outcomes of this analysis revealed that parameters such as section width and concrete strength positively influence the compressive strength index.