Good Strength Development Research Articles

Strength Properties of Clay Based Geopolymer Concrete Using Spent Filter Sand as Fine Aggregates

The high cost of construction materials around the globe has encouraged researchers to make findings on the use of materials within their locality for infrastructure development. This will reduce both construction cost, and environmental pollution caused by manufacturing materials such as Portland Limestone Cement (PLC) which comes with CO2 emission. Hence, this study examined the strength properties of clay based geopolymer concrete made with spent filter sand as fine aggregates. The strength properties of the concrete were tested after curing for 7, 14, 21, and 28 days. The results showed that, the clay soil is under class C ash (sum of acidic oxide equals 55.83%). The highest compressive strength, split tensile strength and flexural strength in 28 days are respectively; 30.33 N/mm2, 6.41 N/mm2, and 6.30 N/mm2. There was good strength development as the curing days increased generally. Hence, the use of SFS in clay based geopolymer concrete did not compromise the strength of the concrete but instead improved the tensile strength and flexural strength by more than 100%.

Application of Palm Oil Fuel Ash as Source Material for Geopolymer Concrete Production

This experimental study examined Palm Oil Fuel Ash (POFA) application as geopolymer binder source material for concrete production. Palm oil residues where sourced from Ogbia in Bayelsa State, cleaned and calcined in an uncontrolled temperature, ground, and sieved through 75 microns BS sieve. Chemical analysis carried out on the POFA using X-ray fluorescence. Sodium silicate and sodium hydroxide mixture in a ratio of 2:5 was used as an activator. Tests carried out on the concrete so produced include compressive, splitting tensile and flexural strengths at 7, 14, 21 and 28 days. It was shown from the results that, combined acidic oxide of POFA was 72.61% which can be grouped under class F pozzolan. The utmost compressive, splitting tensile and flexural strengths obtained for 28 days are 25.23N/mm2, 5.13N/mm2, 3.14 N/mm2 respectively. The strength increased with increase in curing days. Hence, using POFA as source material for geopolymer concrete production had good strength development.

Study the Effect of Using Ceramic Waste Powder as Partial Replacement for Cement on Concrete Properties

Ceramic waste is one of the most active research areas that encompass a number of disciplines including civil engineering and construction materials. Ceramic waste powder is settled by sedimentation and then dumped away which leads to environmental pollution, in addition to forming dust in summer and threatening both agriculture and public health. Therefore, utilization of the ceramic waste powder in various industrial sectors especially the construction, agriculture, glass and paper industries would help to protect the environment. It is most essential to develop eco-friendly concrete from ceramic waste. In this research replacing the (OPC) cement by ceramic waste powder has been studied accordingly in the range of (0, 10, 15, and 20) % by weight of M-30 grade concrete. Concrete mixtures were produced, tested and compared in terms of compressive and tensile strength to the conventional mixture. These tests were carried out to evaluate the mechanical properties for 7 and 28 days. As a result, the CWP cement concretes decreased the workability retention. The values of average hardened concrete density for concrete mixes with CWP cement are higher than the reference mix in 7 days, but lower than the reference mix in 28 days. The maximum value of compressive strengths at 7 and 28 days and tensile strength was achieved at about 5% CWP concrete mix. CWP slowed the compressive strength development especially at early ages. All mixtures with CWP showed good strength development at 28 days. It was observed that all CWP replacement ratios achieved higher compressive strength than characteristic compressive strength which is equal to 30 N/mm2 in 28 days, except the 20% ratio gives 29.72 N/mm2. Test results showed that CWP has potential to be used as an ingredient in concrete mixtures to partially replacing cement. The study showed that concrete mixtures with ceramic waste powder (CWP) had variable performance of the measured properties depending on the replacement level used.

Soluble Pozzolanic Materials from Coal Bottom Ash as Cement Replacement Material

Nowadays, intensive research in production of highly reactive pozzolanic materials from industrial waste to replace cement is crucial. This action expected to increase industrial waste recycling rate and at the same time reduce extraction of non-renewable resources of limestone. Unique characteristics of coal bottom ash as one of the industrial based pozzolan gained less popularity because of its low reactivity and heavy metal leaching due to conventional method used for disposal. Therefore, an alternative approach was deliberated in this research to utilize coal bottom ash into soluble form and enhance the quality of bottom ash as pozzolanic material. Coal bottom ash after the acid washing with optimum parameter was then undergoes solution-gelification process with various alkali based solution for 2 hours soaking durations. The conversion of coal bottom ash into soluble silica in this study demonstrates good pozzolanic performance in a state of siliceous gel pozzolan compared to the raw ones. 5% of cement replacement by soluble silica from CBA shows good strength development from early and later age. The physical dispersion effect is the cumulative effect of enhancement cement hydration due to the availability of increased the nucleation sites on soluble silica particles.

Mechanical and durability properties of recycled aggregate concrete produced from recycled and natural aggregate blended based on the Densified Mixture Design Algorithm method

The aim of this study was to reuse recycled concrete aggregates for concrete production by using the Densified Mixture Design Algorithm (DMDA) method for blended aggregates and mixing design based on the evaluation of characteristics of recycled aggregate concrete (RAC). Recycled coarse aggregate (RCA) was used to replace 30%, 40%, and 50% of the natural coarse aggregate (NCA), respectively, by volume in the samples, and the fine aggregate was a combination of 70% natural fine aggregate (NFA) and 30% recycled fine aggregate (RFA) by volume. A series of tests, including compressive strength, splitting tensile strength, ultrasonic pulse velocity (UPV), electrical surface resistivity (ESR), thermal conductivity (TC), water absorption, and the rapid chloride penetration test (RCPT) were conducted in accordance with the relevant standards. The results illustrated that blending aggregates following to DMDA method suggested an optimum proportion of RCA level which exhibited with highest volume of aggregate per unit volume of combination of RCA and NCA. The results revealed 40% RCA content as the optimum replacement level. Furthermore, the 40% RCA concrete mix exhibited good hardening properties in terms of being only slightly below the 30% RCA mix and significantly higher than the 50% RCA mix. All of the RAC mixtures designed by DMDA method with low cement consumption exhibited good strength development and good durability through 120 days of curing.

Mechanical Behavior of Recycled Fine Aggregate Concrete with High Slump Property in Normal- and High-Strength

This study investigated the mechanical behavior of normal strength (NS) and high strength (HS) concrete containing recycled fine aggregates (RFAs). A high slump mixing design was employed, which may be potentially used as filled structural concrete. The compressive strength, tensile strength, and elastic modulus were measured according to the RFA replacement ratio and curing time. In addition, the shrinkage strain was measured in a temperature and humidity chamber over 260 days. The compressive strength and elastic modulus of RFA concrete were approximately 70–90% of those of virgin concrete. The decreases in the compressive strength and elastic modulus for NS concrete were larger than those for HS concrete. This could be explained by the difference in failure mechanism between NS and HS concrete. The average ratio of the compressive strength at 190 days to that at 28 days was 1.15–1.3, and the ratio of the tensile strength at 190 days to that at 28 days was 1.15–1.25. These demonstrate good strength development. The ratios between the elastic modulus and compressive strength for RFA concrete were dissimilar to those for virgin concrete but similar to those for recycled coarse aggregate concrete. ACI318-14 (Building code requirements for structural concrete and commentary, 2014) and Model Code (Fibmodel code for concrete structures, 2010) overestimated the elastic modulus of RFA concrete. Therefore, this study suggested an empirical expression to approximate the elastic modulus of RFA concrete. The increase in shrinkage owing to the use of RFA was at most 5–6% of the ultimate compressive strain of concrete.

Characteristics of geopolymer hybrid concrete in peat water

Geopolymer hybrid is a combination of geopolymer and Ordinary Portland Cement (OPC) or other binders to produce an alternative binder. This type of binder could be used to transform low-quality fly ash into multi-purpose concrete. Ordinary Portland Cement (OPC) concrete subjected to an acidic organic environment such as peatland, is more prone to deterioration in long-term than concrete using the supplementary cementitious material. In this research, the geopolymer was made by activating low-quality fly ash (contains more than 5% carbon) with the alkaline activator. The inclusion of OPC and Portland Cement Composite (PCC) as a fly ash replacement material is intended to promote curing at ambient temperature and immobilization of heavy metals in fly ash. The specimens were cast and cured at ambient temperature up to 28 days. OPC was used as a control mix. Subsequently, the concrete was immersed in fresh peat water in the laboratory up to 28 days. Characteristics of the geopolymer hybrid such as compressive strength, porosity, and leaching were determined. Microstructure analysis, such as SEM-EDX and FTIR, were conducted. Results show that the geopolymer hybrid has a good strength development at early days. At 28 days, there was a reduction of strength and increase of porosity, probably due to the attack of calcium from the OPC concrete. There was a transformation of aluminosilicate gel into C/N-A-S-H that is advantageous for the strength development at the early days. However, a weaker material has formed in the long term that cannot resist further acid attack. It can be concluded that the geopolymer hybrid is a promising binder, but it is essential to design the material appropriately to have better strength, durability and environmental properties in the long term.

A methodology to improve nanosilica based cements used in CO2 sequestration sites

Abstract Attempts to reduce the amount of greenhouse gases released into the atmosphere in recent years have led to the development of Carbon Capture and Sequestration (CCS) technology. However, there have been many studies reporting leakages form CO2 storage sites as a result of cement degradation induced by generation of an acidic environment in the storage site. Although there are a number of approaches proposed to enhance the efficiency of the cement, the degradation issue has not been totally resolved yet perhaps due to the excessive corrosives nature of carbonic acid and supercritical CO2. The aim of this study is to propose a methodology to improve the physical and mechanical characteristics of the cement by nanomodification such that a consistent rheology, constant density and a good strength development can be achieved. A new dispersion technique was proposed to ensure that the cement formulation gives a consistent result. The results obtained indicated that unlike the literature mixing, cement slurries prepared by the new mixing technique are very consistent in their rheology, regardless of the sonication parameters chosen. The measurements of the compressive strength performed at the reservoir condition revealed that nanosilica contributes in the strength development up to a certain point. Thermogravimetric Analysis (TGA) conducted at the last stage indicated that the amount of Portlandite left in the cement by adding nanosilica is decreased due to the pozzolanic reaction, which would help the cement to have a higher chance of survival in a storage site. However, cautions must be taken to maintain a certain amount of Portlandite in the cement for slowing down the carbonation rate, as otherwise the matrix of the cement is attacked directly and the cement will be degraded very fast.

Effects of South African Silica Sand Properties on the Strength Development and Collapsibility of Single Component Sodium Silicate Binders

Abstract This study shows the results of the investigation of the strength performance, and residual strength of a single component inorganic binder system Cast Clean S27®. The study was conducted using three different foundry sand sources in South Africa. Sample A is an alluvial coastal sample, sample B is an alluvial riverbed sample and Sample C is a blasted sample from a consolidated quartzite rock. The binder was also cured using three different curing mechanisms. The aim of the investigation was to determine the variation of strength performance and residual strength between the different South African sand sources based upon the physical and chemical properties of the sand sources. The moulding sand was prepared using three possible curing mechanisms which are carbon dioxide curing, ester curing and heat curing. The strength measurements were determined by bending strength. Sample A and sample C sand had good strength development. Sample B sand had inferior strength development and excellent high temperature residual strength. The study showed that the single component inorganic binders have good strength development and low residual strength. The silica sand properties have major contributing factors on both strength development and residual strength. The degree of influence of silica sand properties on strength performance and residual strength is dependent on the time of curing and method of curing.

Experimental analysis of behaviour of light weight high performance concrete with crystallized slag

Purpose The aim of this paper is to make lightweight high-performance concrete (LWHPC) with high economic performance from existing materials on the Algerian market. Concrete with high values with regard to following properties: mechanical, physical, rheological and durability. Because of the implementation of some basic scientific principles on the technology of LWHPC, this study is part of the valuation of local materials to manufacture LWHPC with several enhanced features such as mechanical, physical chemical, rheological and durability in the first place and with regard to the economic aspect in the second place. Design/methodology/approach The experimental study focused on the compatibility of cement/superplasticizer, the effect of water/cement ratio (W/C 0.22, 0.25, 0.30), the effect of replacing a part of cement by silica fume (8 per cent), the effect of combined replacement of a part of cement by silica fume (8 per cent) and natural pozzolan (10 per cent, 15 per cent, 25 per cent) and the effect of fraction of aggregate on properties of fresh and hardened concrete using the mix design method of the University of Sherbrooke, which is easy to realize and gives good results. Findings The results obtained allow to conclude that it is possible to manufacture LWHPC with good mechanical and physical properties in the authors’ town with available materials on the Algerian market. The mix design and manufacture of concrete with a compressive strength at 28 days reaching 56 MPa or more than 72 MPa is now possible in Biskra (Algeria), and it must no longer be used only in the experimental field. The addition of silica fume in concrete showed good strength development between the ages of 7 and 28 days depending on the mix design; concrete containing 8 per cent silica fume with a W/B (water/binder) of 0.25 has a compressive strength higher than other concretes, and concrete with silica fume is stronger than concrete without silica fume, so we can have concrete with a compressive strength of 62 MPa for W/C of 0.25 without silica fume. Then, one can avoid the use of silica fume to a resistance of concrete to the compressive strength of 62 MPa and a slump of 21 cm, as silica fume is the most expensive ingredient in the composition of the concrete and is very important economically. A main factor in producing high-strength concrete above 72 MPa is to use less reactive natural pozzolan (such as silica fume) in combination with silica fume and a W/B low of 0.25 and 0.30. The combination of silica fume and natural pozzolan in mixtures resulted in a very dense microstructure and low porosity and produced an enhanced permeability of concrete of high strength, as with resistance to the penetration of aggressive agents; thus, an economical concrete was obtained using this combination. Research limitations/implications The study of the influence of cementitious materials on concrete strength gain was carried out. Other features of LWHPC such as creep, cracking, shrinkage, resistance to sulphate attack, corrosion resistance, fire resistance and durability should be also studied, because there are cases where another feature is most important for the designer or owner than the compressive strength at 28 days. Further studies should include a range of variables to change mixtures significantly and determine defined applications of LWHPC to produce more efficient and economical concretes. It is important to gather information on LWHPC to push forward the formulation of characteristics for pozzolan concrete for the building industry. Practical implications The LWHPC can be used to obtain high modules of elasticity and high durability in special structures such as marine structures, superstructures, parking, areas for aircraft/airplane runways, bridges, tunnels and industrial buildings (nuclear power stations). Originality/value The novel finding of the paper is the use of crystallized slag aggregates and natural pozzolan aggregates to obtain LWHPC.

Mineral Composition and Performance of Phosphoaluminate Clinker with Addition of SO<sub>3</sub>

The effect of SO3 on the mineral composition and performance of phosphoaluminate clinker was investigated by means of XRD, IR and SEM. Also, the compressive strength of clinker was performed. The experimental results showed that a certain amount of SO3 would promote the formation of calcium phosphoaluminate mineral, which was good for the strength development of phosphoaluminate clinker. Moreover, the addition of SO3 was benefit to the formation of C4A3 in phosphoaluminate clinker. So, the 5% dosage clinker owns a good strength development.

Activation of anhydrate phosphogypsum by K2SO4 and hemihydrate gypsum

Lime pretreated phosphogypsum(PG) was calcined at 500 °C to produce anhydrate gypsum cement. Due to the slow hydration of anhydrate gypsum, additives, K2SO4 and hemihydrate gypsum were selected to accelerate the hydration of anhydrate. The hydration characteristics, the resistance to hydrodynamic water, and the mineralogical studies were investigated. The experimental results suggest that activated by K2SO4 and hemihydrate, anhydrate PG hydrates much more rapidly than that in the presence of only K2SO4 or in the absence of additives. The binder has proper setting time, good strength development, and relatively better resistance to water. The hardened binder has hydrated products of rod or stick like shaped dihydrate gypsum crystals.

Effects of w/c ratio and curing conditions on strength development in BRECEM concretes

The early strength development of ‘BRECEM’ concretes, made from 50:50 mixtures of calcium aluminate cement (CAC) and ground granulated blastfurnace slag (ggbs), using 100-mm cubes at w/c ratios of 0.35 and 0.45, has been studied. BRECEM concretes showed good strength development at both w/c ratios whether water cured or air cured. In contrast, longer-term studies with 1-m cubes cured under near-adiabatic conditions have indicated that mass BRECEM concretes of similar binder composition may gain compressive strength relatively slowly. This is primarily due to the heat of hydration of the CAC component, which can lead to temperatures of up to 60°C, resulting in rapid hydration and conversion of the calcium aluminate component. However, the performance of 40 CAC/60 ggbs concrete under these near-adiabatic conditions has proved to be satisfactory over a period of 5 years, with similar strength development to that of equivalent 100-mm cubes stored under ambient conditions.

Calcium sulfoaluminate cements—low-energy cements, special cements or what?

Calcium sulfoaluminate, C4A3S or CSA, often known as Klein s compound, can be readily synthesized as a single phase at about 1300°C. It is also formed along with belite and a ferrite phase when limestone is reacted with various minerals or waste products at 1200–1300°C. The presence of CSA can lead to early strength development, and such systems may be regarded as low-energy cements, providing environmental benefits, notably emission of less carbon dioxide than in the production of Portland cement. Under controlled, specified conditions, usually including addition of gypsum, the hydration of CSA gives acceptable setting times and good strength development. These properties are based on the rapid formation of ettringite and variable quantities of an amorphous gel phase. These characteristics have already led to the formulation of various commercial products taking advantage of these special properties for applications in building chemistry and mining. Further systematic research is required leading to greater application of these novel cements.

Application of High-Volume Fly Ash Concrete to Marine Structures

Abstract A new material with high content of fly ash named ‘Ashcrete’ has been developed. to examine the applicability of Ashcrete to marine structures, strength characteristics, resistance to sea water attack, and safety in the marine environment have been studied. the following results have been obtained: 1) the strength characteristics of high-volume fly ash concrete depend upon the type and proportions of chemical activators as well as curing conditions. 2) Ashcrete using sodium chloride (NaCI) as a chemical activator shows high initial strength and good strength development with age. 3) Ashcrete containing NaCI activator shows good resistance to sea water from the viewpoint of its strength characteristics, volume changes and microstructurcs. 4) Since 1980 many types of large-scale artificial reefs made of Ashcrete have been installed in the sea. As a result of long-term studies and underwater observations, the Japanese Government has demonstrated the durability of the material, safety in the marine e...

Sulphate Durability of Plain and Fly Ash Mortars

ABSTRACTSulphate expansion and strength tests were performed on mortars containing equal proportions of Type 10 (ASTM Type I) Portland cement and fly ash as the cementitious material. Two intermediate-Ca subbituminous ashes, one high-Ca subbituminous ash and one bituminous ash were tested. Control mortars manufactured with Types 10 and Type 50 (Type V ASTM) cements and one mortar containing 50% replacement of cement with limestone powder were also examined. The period and temperature of curing prior to sulphate exposure and the concentration and pH of the attacking solutions were other test parameters. Results indicate that the two intermediate-Ca subbituminous ashes from Alberta Canada, combined with Type 10 cement produce mortars that show excellent long-term strength, acceptable short term strength, and are highly resistant to attack by aggressive sulphate solutions. In some cases durability of these mortars was better than the control mortar made with Type 50 cement. On the other hand, mortar made using the high-Ca ash showed very high susceptibility to sulphate attack; at the same time, mortars made with this ash showed good strength development. Qualitative x-ray diffraction analysis indicates the presence of more lime, magnesium and iron bearing crystalline compounds in the high-Ca ash than in the Alberta ashes. These appear to be responsible for the poor performance in sulphate environments.