Cement Sand Research Articles

Influence of surface reinforcement on the strength of brick masonry wall

In this article, an attempt is made to evaluate the load carrying capacity of one brick thick vertical, surface reinforced masonry wall and compared with unreinforced wall. Locally available bricks of compressive strength of 4–8 MPa is used in study. Basic properties of bricks and three types of mortars are evaluated. Compressive strength, shear bond and flexural bond strength of English bonded prisms is also explored. Experimental results indicated bond strength of English bonded prisms built with cement sand mortar and cement soil mortar was comparable. Use of lime showed reduced bond strength and compressive strength. Use of vertical reinforcement in masonry construction is mainly devoted for resisting lateral forces. Compressive strength of 0.1% externally reinforced masonry wall was 7.4% more when compared to unreinforced masonry. Similarly, modulus of elasticity of reinforced masonry wall is 2.08 times of unreinforced masonry wall.

Finite deformation hyperplasticity theory for crushable, cemented granular materials

The work is focused on the formulation of a thermodynamically–based constitutive theory for granular, cemented geomaterials, often characterized by a open structure with high porosity and voids of large diameter. Upon mechanical degradation processes such as bond rupture and grain crushing, these material undergo large volumetric and shear strains, and in some cases the deformations are so large that the usual assumption of linearized kinematics may be not applicable. In the first part of this work, the theory of hyperplasticity is extended to the finite deformation regime by adopting a multiplicative split of the deformation gradient into an elastic and a plastic part, under the assumption of material isotropy. Grain breakage and bond damage processes are accounted for through two micromechanically–inspired internal variables. A specific constitutive model for carbonatic cemented sands and calcarenites is proposed as a relevant example of application. In the second part, an implicit stress–point algorithm has been developed which is amenable to closed form linearization, for the implementation of the model into standard FE platforms. A series of numerical tests have demonstrated the accuracy and efficiency of the proposed algorithm. The simulation of plane strain biaxial tests, modeled as boundary–value problems, has highlighted the role played by geometric non–linearity in determining the evolution of the specimen deformation upon reaching a bifurcation condition.

Bio-Cementation of Sandy Soil through Bacterial Processing to Precipitate Carbonate

Bio-cement built on microbial induced carbonate precipitation MICP, be able to consolidate the loose grains and can applied for soil reinforcement. In this study, the performing of an ureolytic Sporosarcina Pasteurii for sand stabilization was estimated. The S. Pasteurii Could effectively consolidates sand particles through urea hydrolysis and the successive production of calcite. The bio improved sands had relative great compressive strength after 60 days exposure to bacterial cells injections cycles. The compressive strength of bio stabilized sands was reliant on the utilized cell concentrations and density of urea and CaCl2. High bacteria cell masses decreased the compressive strength. The optimal density of cell, was OD600 0.5, when cost and performance were taken into account. The study shows that bio cementation of sand built on microbial induced carbonate precipitation (MICP) has ability for the reduction of sand permeability through pore clogging with precipitated carbonate.

Seismic Capacity Assessment of Unreinforced Brick Masonry Building Performed According To Eurocode

Brick Masonry Building with cement sand mortar is a common type of building typology in Nepal. Regardless of being one of the eldest construction technology, the behavior of masonry building is still a matter of study. The uncertainty in the behavior of masonry structures is due to material heterogeneity, complex behavior under different loading conditions and may be due to less research in this arena. Different modeling strategies are used and proposed worldwide to design and to identify the seismic performance of Masonry Building. The analysis strategy ranges from the simple linear method, equivalent frame method, static nonlinear method to dynamic nonlinear, which may be chosen according to engineering design aims and research purpose. In this attempt, authors choose two degrees of freedom 3D model of Unreinforced Brick Masonry Structures which catches both overturning and hysteresis mechanisms due to the shear response implemented by the TREMURI program with static nonlinear procedures. This verified method of modeling and analysis is applied to assess the performance of three different Unreinforced Brick Masonry buildings of the same plans with different numbers of storey.

Effect of silica fume on the ultrasonic pulse velocity of cemented sand

One of the geotechnical engineering strategies for dealing with weak soils in a construction site is to modify their mechanical properties with the aid of soil improvement techniques. Chemical stabilization of soil using cement is one of these effective approaches that can considerably enhance workability and shear strength parameters of soil. However, very limited investigations have been carried out to reveal the effect of silica fume on the ultrasonic pulse velocity (UPV) and the ultrasonic stiffness (Eu) of cement-treated sandy soil. For this purpose, in the present research, a series of UPV tests were performed on sand-cement-silica fume specimens. The cement percentages were 3, 5 and 7% and silica fume contents were 0, 0.25, 0.5 and 1% by weight of dry sand. The cylindrical samples were prepared and cured for 3, 7, 14, 28, 42 and 56 days and tested. The results show that inclusion of silica fume to the cemented sand increases UPV and Eu which this enhancement is more pronounced at longer ages.

Strength and Permeability Characteristics of Superfine Cement and Fine Fly Ash Mixture Grouted Sand

Strength and Permeability Characteristics of Superfine Cement and Fine Fly Ash Mixture Grouted Sand

Сement Mortars with Alkali-Free Accelerators under Test Conditions for Alkali-Silica Reactions

The results of long-term and accelerated tests of cement–sand mortars with a reactive aggregate and additives Al2(SO4)3 and Fe2(SO4)3, carried out under the conditions of the corresponding standardized techniques, indicate that these additives suppress the development of destructive expansion deformations of mortars and concretes caused by alkali-silica reaction. In all samples of cement–sand mortars, after accelerated and long-term tests, destructive changes occurring with particles of reactive aggregate were noted. Ettringite was found in samples after long-term tests (its content is higher in samples with additives of aluminum and iron sulfates), whereas in samples subjected to accelerated tests in NaOH solution, ettringite rapidly decomposes with the formation of a hydrogarnet phase. The results of an energy dispersive microanalysis of an alkali-silicate hydrogel formed as a result of an alkali-silica reaction do not allow explaining the ability of aluminum and iron sulfates to suppress expansion deformations by their influence on the chemical composition of the hydrogel and, accordingly, on its destructive properties. It can be assumed that the presence in the samples of other phases (ettringite and hydrogarnet phase), the formation of which is promoted by additives, can have a restraining effect on the dynamics of the development of destructive expansion deformations.

Fabrication of sand-based novel adsorbents embedded with biochar or binding agents via calcite precipitation for sulfathiazole scavenging

Fabrication of efficient and low-cost adsorbents through enzyme induced carbonate precipitation (EICP) of sand embedded with binding agents for sulfathiazole (STZ) removal is reported for the first time. Sand enriched with biochar (300 °C, 500 °C, and 700 °C), xanthan gum, guar gum, bentonite, or sodium alginate (1% w/w ratios) was cemented via EICP technique. Enrichment with binding agents decreased the unconfined compressive strength, improved the porosity, and induced functional groups. Biochar enrichment reduced the pH, and increased the calcite contents and electrical conductivity. Fixed-bed column adsorption trials revealed that biochars enrichment resulted in the highest STZ removal (64.7–87.9%) from water at initial STZ concentration of 50 mg L−1, than the adsorbents enriched with other binding agents. Yoon–Nelson and Thomas kinetic models were fitted well to the adsorption data (R2 = 0.91–0.98). The adsorbents embedded with 700 °C biochar (BC7) exhibited the highest Yoon–Nelson rate constants (0.087 L min−1), 50% breakthrough time (58.056 min), and Thomas model-predicted maximum adsorption capacity (4.925 mg g−1). Overall, BC7 removed 168% higher STZ from water than pristine cemented sand. Post-adsorption XRD and FTIR analyses suggested the binding of STZ onto the adsorbents. π–π electron-donor-acceptor interactions, aided-by electrostatic interactions and H-bonding were the main STZ adsorption mechanisms.

Experimental investigation on compression resistance of bio-bricks

The cementation of sand into bio-brick materials through microbial induced calcium carbonate precipitation (MICP) is a novel technology with broad applications. The compression strength of the MICP treated bio-bricks was tested through brick compression tests. Additives including discrete randomly distributed fiber, coarse sand, and clay and multiple treatments were applied to reinforce the compression strength of bio-bricks. Results concluded that the increase of compression strength with treatment times for all bio-bricks seems to be intuitive – the more treatment times, the higher compression strength. The addition of synthetic and natural fibers can result in the increase of compression strength of the bio-bricks by 50–70%. The optimum clay content of strengthening brick compression strength is 2%. The contribution of void space from additional coarse sand on brick compression strength is insignificant. The water absorptions of bio-bricks ranged from 10.16% to 17.89%, which is comparable with that of traditional red bricks. Moreover, the overall results from FTIR, XRD, and SEM demonstrated the process of MICP and identified the formation of vaterite and calcite in the bio-bricks.

Research on Mix Proportion Design Method of Cement Concrete for Road Mixed with Antifreeze Admixtures Sealed in Capsules

In order to explore the influence of a new mixed type antifreeze material on the flexural strength of concrete for road, the orthogonal design method was used to conduct experimental research on six factors including the water-binder ratio, the antifreeze material content, the fly ash content, the feeding process, the shape of the antifreeze material and the pre-absorption of antifreeze material. The influence degree of various factors on the flexural strength of concrete was studied, and the mixing ratio design method of concrete for road mixed with the antifreeze material was given. It was found that the water-binder ratio is the main factor affecting the strength of the concrete and that when the amount of antifreeze material is less than 15%, the effect on the strength is small. The influence of other factors on the strength is greatly influenced by the interaction of water-binder ratio. When it comes to the mix design, the content of gelling material is 500 kg/m3, and the water-binder ratio changes from 0.35 to 0.43 under different traffic levels. The recommended antifreeze material content and fly ash content is 10% and 15% respectively. It’s also suggested that the antifreeze material should be pre-absorbed, and the cement sand and stone be mixed before the antifreeze material is put into the mixing.

Properties of Sand Cement Brick Containing Quarry Dust (SCBQD) and Bacteria Strain

Sand cement brick among favorable building material for low cost house construction due to its low price. Technology development in building material already explored varies waste to be added in improving properties of building materials. Beside that addition of bacteria in building material also proven in literature to improve its properties. In this research addition of bacteria in the cement sand block containing quarry dust (SCBQD) was studied. Several properties namely, compressive strength, depth of carbonation, initial rate of suction (IRS) and water absorption were studied. SCBQD is made from sand, cement, quarry dust and chipping using industrial mix design. In this study, 3% of Enterococcus faecalis (EF) and 5% of Bacillus sp (BSP) bacteria was added in the SCBQD mixes. Three SCBQD mixes were prepared including the control mix without bacteria, SCBQD with 3% EF and SCBQD with 5% BSP. Natural fine aggregate was replaced partially with the quarry dust. 100 mm SCBQD cubes were used to conduct compressive strength, depth of carbonation, initial rate of suction and water absorption test at 7, 14 and 28 days. The experimental results showed that the compressive strength value of SCBQD with addition of bacteria was increased for all curing ages. At 28 days of curing, the compressive strength value for control SCBQD containing quarry without any addition of bacteria is 3.30 MPa, while SCBQD containing quarry dust with addition of 3% of EF bacteria is 3.57 MPa and for SCBQD with 5% of BSP bacteria the value is 4.90 MPa. On the other hand, SCBQD containing 3% EF and 5% BSP gained lower IRS and carbonation depth. Depth of carbonation at 28 days was decreased 9.3% and 20% for SCBQD containing 3% EF and 5% BSP, respectively. Meanwhile, 28-day IRS was reduced 12.9% and 22.6% for SCBQD containing 3% EF and 5% BSP, respectively. In overall, the result shows that, SCBQD with 5% BSP as proven positive and better results when compared to control SCBQD and SCBQD with 3% EF bacteria which is absorb of 12.02% in water absorption. The findings showed that bio-SCBQD containing industrial waste and bacteria has good potential to be used as building material.

The Mechanical Properties of Brick Containing Recycled Concrete Aggregate and Crumb Rubber as Sand Replacement

Recycled Concrete Aggregate (RCA) and crumb rubber are one of the recyclable building wastes. This would be the good candidate to replace the natural aggregate in concrete, since we know these material’s physical properties are strong and ductile. In concrete production, demand for sand has increased which has led to problems in the industry. As a result, the sand price rose, which in effect influenced the cement and sand brick prices. This research focuses on sand cement brick performance, containing recycled concrete aggregate and crumb rubber. This study aims to determine the mechanical properties of sand cement brick containing recycled concrete aggregate (RCA) and crumb rubber (CR) wastes, such as compressive strength and water absorption. The brick specimens were prepared using 100 % natural sand, they were then replaced by RCA at 15%, 30%, 45% and 60% with proportions of CR consisting of 1.5%, 3.0%, 4.5% and 6.0% by weight of natural sand. Just RCA 60 percent with 6.0 percent CR achieves lower strength than normal bricks based on the compressive strength tests whereas others display a high strength. Nevertheless, as predicted, all design mix reaches strength greater than 7N/mm2. Besides that, 30 per cent of RCA with 3.0 per cent CR is the most desirable mix design that achieves high compressive power.

Performance evaluation and microstructure characterization of seawater and coral/sea sand alkali-activated mortars

To adequately develop the application of marine resources for island construction and effectively promote the sustainability of industrial resources, this paper investigates the feasibility of using seawater and coral or sea sand as replacements for freshwater and river sand in alkali-activated mortars (AAMs) containing ground blast furnace slag (GBFS), fly ash (FA), and silica fume (SF). Five different mortar mixtures were designed: seawater and coral sand alkali-activated mortar (SC-AAM), seawater and sea sand alkali-activated mortar (SS-AAM), freshwater and river sand alkali-activated mortar (FR-AAM), seawater and coral sand cement mortar (SC-OPC), and freshwater and river sand cement mortar (FR-OPC). The differences in the workability (slump), setting time, compressive strength, flexural strength, and drying shrinkage of the prepared cement mortars and AAMs were compared. Then, the microstructure and crystalline phases of the mortar samples were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectrometry. The experimental results indicated that the utilization of seawater and coral or sea sand promoted the formation of C-S-H gel phases. Additionally, the existence of coral sand decreased the slump and initial setting time of the mortars due to the high water absorption and porosity of the coral aggregate. The SC-AAM exhibited higher compressive and flexural strengths at an early age and had a lower drying shrinkage than other AAMs, which can be attributed to the natural internal curing effect of the coral sand and the dense interfacial transition zone between the aggregate and the binders. The weak strength of coral sand had no effect on the strength development of the mortars in AAM production. However, the SS-AAM had a relatively low compressive strength and a large drying shrinkage in comparison to other mortar samples due to the existence of more free water.

Properties of fly ash cement brick containing palm oil clinker as fine aggregate replacement

Environmental pollution caused by disposal of by-product from local industries namely fly ash from coal power plant and palm oil clinker generated by palm oil mills needs to be resolved. This research examines the effect of palm oil clinker as partial sand replacement on properties of fly ash cement sand brick. Five brick mixes were prepared using fly ash blended cement as the binder. Other mixes were produced by varying the quantity of pulverised palm oil clinker ranging from 0%, 10%, 20%, 30% and 40% by weight of sand. All specimens were water cured for 28 days. The specimens were subjected to compressive strength, flexural strength and water absorption test. Utilization optimum amount of clinker of 30% enhances the brick strength owing to the pozzolanic effect of fine clinker. The chemical reaction between calcium hydroxide and silicon dioxide forms extra CSH gel that contributes to pore refinement and higher strength of brick.

Effects of cement content and curing period on strength enhancement of cemented calcareous sand

Cement treatment is a promising and effective method to enhance strength of calcareous sand in regions where offshore foundations and coastal facilities are localized. In treatment, the added cement content and curing period influence the strength of cemented calcareous sand. In order to regulate the loading resistance of cemented calcareous sand, effects of cement content and curing period on strength enhancement are investigated experimentally. First, cemented specimens with 5%, 7.5%, and 10% cement contents and 1–28 days curing period are prepared. Then, unconfined compression test is conducted to measure strength. Nuclear magnetic resonance test is also performed to analyze microstructure change during hydration reaction. An empirical equation of strength is derived, considering the effects of cement content and curing period. This equation shows higher accuracy than existing empirical models. In addition, the microstructure change in hydration process is quantified by pore volume evolution. Void ratio is used to characterize the pore volume evolution. Hence, the dependence of strength on cement content and curing period is quantitatively explained by the change in void ratio. This sheds light on hydration reaction in cement treatment by cement content and curing period and the regulation of strength enhancement in cemented calcareous sand. Highlights Empirical equation on strength with effects of cement content and curing period Pore volume evolution by hydration reaction in cement treatment Characterization of microstructure change by void ratio Microscopic mechanism of strength enhancement for cemented calcareous sand

Synthesis of Geopolymer from Coal Fly Ash and its Comparative Study with Fly Ash Based Ordinary Nepalese Cement

The world cement industry is responsible for 5-8 % of the total CO2 emission. Thus, the cement industry has a crucial role in global warming. The search for an alternative green inorganic binder with improved durability led to the discovery of alkali-activated binder termed “geopolymer”. In this study, geopolymer was synthesized from coal fly ash (CFA) with the parameters such as particle size ≤ 53 μm, NaOH concentration 8 M and the mass ratio of CFA/Na2SiO3 was 0.75. For the comparative study with fly ash based cement, the cement mortars were prepared by varying the cements and mass ratio. The highest compressive strength (14.16 MPa) of the cement mortar was however obtained with 1:3 cement sand ratio after 7 days of curing, the ratio of 1:4 was considered for comparison. The cement and geopolymer mixture mortars were also prepared with varying (cement + sand) and (CFA+ NaOH+ Na2SiO3) mass ratio. The maximum compressive strength of 3.84 MPa was obtained for 1:2 mass ratio with 7 days of curing. The maximum compressive strengths of CFA based geopolymer, CFA added cement and cement and geopolymer mixture were 17.06, 21.3 and 11.42 MPa with 90 days of curing respectively.

Modelling of sand cement hydration in normal conditions

The paper considers the hardening mechanisms of the sand cement composition (0.75 sand and 0.25 Portland cement) during 28 days. In this study, the VCCTL tool is used for computer modelling of the sand cement hardening process. It is found that after 28 days, the sand cement hydration is ∼0.75, the porosity is over 0.20 and 0.32 at the water-cement ratio of 0.40 and higher, respectively. Calcium silicate hydrate (C–S–H) and portlandite (CH) are the main hydration products of Portland cement and responsible for the sand cement strength. Owing to the high porosity of sand cement, free moisture is present in it in large quantities. It is shown that the effective elastic moduli of sand cement rapidly grow during 200 hours and then monotonically lower. The yield stress monotonically grows during sand cement curing, and at 0.40 and 0.44 water-cement ratios achieves the maximum value. This growth thus depends on the water-cement ratio and affects Young’s modulus during the curing process. At the qualitative level, a correlation is observed between the yield stress and Young’s modulus depending on the curing time of sand cement with the discussed water-cement ratios.

Electrical resistivity and elastic wave velocity of sand–cement–inorganic binder mixture

Cement-based grout has been used for ground improvement. Owing to environmental issues related to cement, its usage should be reduced. In this study, an inorganic binder is introduced to reduce the use of cement in grout. To evaluate the transient electrical and mechanical properties of the sand–cement admixture samples improved with the addition of inorganic binders, two non-destructive testing methods, the electrical resistivity and free–free resonant column tests, were adopted in addition to the unconfined compressive strength (UCS) test. Experimental tests were performed considering four different mixing ratios and three different cement contents, depending on the curing time. The results show that the mixing ratio and curing time have considerable effects on the electrical and mechanical properties of the mixture. The UCS decreases as the cement content decreases. However, sufficient UCS is expected to be obtained when the inorganic binder content is increased in the mixture. From the results, it is found that geotechnical properties of the mixture can be estimated in the field with proper non-destructive testing methods. It is expected that the data and trends proposed in this study can be used as a reference in predicting grouting quality in the field.

Comparison of strength of sandcrete blocks produce with fine aggregate from different sources

Sandcrete blocks comprise of water, natural sand cement. Sandcrete blocks are the building units used in the construction of wall and partitions. Diverse sizes of sandcrete blocks are used to construct free standing walls and building structure with load and non – load bearing units. This research work investigate and compared strength of sandcrete blocks produced with fine aggregate from different source in Owo local government area. The targeted areas within Owo local government are Emure, Ipele and Shagari. Sieve analysis was conducted on the samples and the result revealed that all the samples are good for sandcrete block production. Thirty six sandcrete cubes samples were mould. The mix proportion 1:6 was used. Batching by volume was adopted. Curing was done by full immersion of sandcrete and compressive strength test was carried out on each specimen at 7, 14. 21 and 28 days respectively. The percentage of fine aggregate used in this research was 100% for all samples. The results revealed that sandcrete blocks produced with fine aggregate from Ipele, Shagari and Emure gives compressive strength of 4,15N/MM2, 3.56N/MM2 and 5.48N/MM2 at 28 days respectively. Based on the result of this research work, it is recommended that Emure fine aggregate (sand) is considered as most suitable out of the samples tested for sandcrete blocks production.
 Keywords: Sand, Sandcrete blocks, Compressive strength, Curing, Production practice.

Methane Derived Authigenic Carbonate (MDAC) Aragonite Cemented Quaternary Hardground from a Methane Cold Seep, Rathlin Basin, Northern Ireland: δ13C and δ18O Isotopes, Environment, Porosity and Permeability

A block of sandstone retrieved by divers from near Rathlin Island, Co. Antrim, Northern Ireland, represents an aragonite cemented sand formed during the Quaternary. Strongly negative δ13C of the aragonite cement (−50 to −60‰ δ13C) indicates that the hardground was formed by the anaerobic oxidation of methane (AOM), resulting in the formation of a methane-derived authigenic carbonate (MDAC) hardground. Such hardgrounds have previously been recorded as forming extensive pavements in deeper waters in the mid Irish Sea (e.g., Croker Carbonate Slabs), although the latter also contains high-magnesium calcite. Sand was initially deposited as part of a storm lag deposit, with a reworked bivalve and gastropod fauna. This sand was then colonised by a probable crustacean fauna, producing horizontal open dwelling burrows (Thalassinoides). After aragonite cementation, the hardground was colonised by boring bivalves, with slightly negatively elevated levels of δ13C. Finally, the hardground was colonised by an encrusting fauna (bryozoans, calcareous algae and serpulids), by then in warmer seas. Continued depleted levels of δ13C present within the encrusting fauna (−1 to −5‰ δ13C) indicate continued methane generation and seepage, which may still be active to the present day, and to the possibility of shallow gas reserves. The δ18O values change between macro-infauna vs. encrusters, indicating a warming in water temperature, reflecting glacial and post-glacial environments. The aragonite cemented sandstone has a highly variable porosity, with large vugs (open burrows and borings), smaller mouldic porosity within gastropods and bivalves and complex micro-porosity associated with acicular aragonite cements. Overall permeability was recorded at the 2.5 to 23 Darcies level, reflecting the highly variable vuggy porosity, although matrix permeability was around 100 mD and controlled by the MDAC fabric. Actual permeability will likely be controlled by the extent to which larger pores are interconnected. The sea around the Rathlin Island area contains a diverse fauna, which is worthy of future study in the context of cold seep and MDAC pavement formation.