Dry-mixed Mortar Research Articles

Research on Rapid Detection Technology and Application of Mortar Compressive Strength Based on Neural Network

Since the rapid development of the construction industry, the production of construction waste has also multiplied, and the construction waste has caused tremendous pressure on the environment. Therefore, the main research of this subject is that the waste concrete is formed into a recycled material after a certain treatment--concrete powder. And the cement in the dry-mixed mortar is replaced by 0-30% concrete powder. The compressive strength of recycled concrete powder under different dosages was tested by experimental method. The compressive strength is then applied to the artificial neural network to establish a predictive model. Taking time as a variable, the feasibility and the best dosage of the 28-day compressive strength method for the 3d compressive strength during the test are discussed. In order to reduce the test cycle, improve work efficiency, and ultimately achieve the purpose of improving construction waste utilization.

High temperature performance of wet-mix and dry-mix mortars prepared with different contents and size gradings of glass aggregates: Hot test and cold test

This paper presents the mechanical property of wet-mix and dry-mix mortars prepared with different contents and size gradings of glass aggregates after exposure to an elevated temperature of 800 °C. The tests were performed during 800 °C exposure (hot test) and after cooling from 800 °C to room temperature (cold test). In the cold test, the residual compressive strength of both the wet-mix and the dry-mix mortars increased with increasing content and decreasing particle size of glass aggregates. However, for the hot test, when the replacement of river sand by the glass aggregates was above 15%, the residual compressive strength sharply decreased. This was attributed to the glass aggregates were softened and the semi-melted glass acted like “soft” aggregates which were unable to sustain stress (loading) under the hot test. Unlike the improvement mechanism through better bonding between the re-solidifying glass aggregates and the cement matrix after cooling, the optimal performance of the mortars prepared with 15% of glass aggregates to replace river sand in the hot test was attributed to the penetration of the softened glass into the empty pores during loading. Further reducing the percentage of glass aggregates led to decrease in strength due to the excessive thermal expansion of river sand in the mortars. Compared with the cold test, the impact of glass particle size was less obvious on the residual strength for the hot test. Due to their higher porosity, the dry-mix mortars performed better than the wet-mix mortars under both the hot and cold test conditions.

玄武岩石粉对机制砂干混砂浆性能影响研究

玄武岩石粉对机制砂干混砂浆性能影响研究

Behaviour of dry mix EPs mortar panel under axial eccentric loading

Lightweight mortar panel has been an alternative wall in the construction. However, the unsteady distributions of loads to the panel due to disorder alignment during construction affect the capability of the wall to reach the optimum load capacity. The inclusion of expanded polystyrene (EPs) that less in density and strength also was contributed the factor to achieve cohesiveness the properties of mortar panel. Therefore, this study aimed to determine the load capacity of the panel under axially eccentric loading that comply with the design of plain wall in BS8110-1. Due to this type of loading, the deformation was investigated through the load-strain, buckling profile and failure mode. This research involves laboratory experimental work for the different panel’s height. Four variables of EPs proportion were designed in a dry-mix mortar and constructed into the panel. From the result, the panel failed in compression stress where the wall deflected in single and double curvature at the vertical position. The high slender panels were failure at the joint of panels with the maximum deflection of 3.96 mm. Meanwhile, the low slender panel tended to crack and bend at the top. The ultimate eccentric load obtained for the panel at 45% EPs replacement was 587.76 kN.

Effects of Chemical Admixtures on the Working and Mechanical Properties of Ordinary Dry-Mixed Mortar

The effects of hydroxypropyl methyl cellulose ether, starch ether, bentonite, and redispersion emulsoid powder on the working and mechanical properties of fresh dry-mixed mortar were studied. The results show that hydroxypropyl methyl cellulose ether has the greatest impact on the consistency and water retention of ordinary dry-mixed mortar and that redispersion emulsoid powder reduces the water action and starch ether has essentially no effect on water retention. It also shows that the time of mortar condensation when mixed with hydroxypropyl methyl cellulose ether is the longest, followed by redispersion emulsoid powder and bentonite. Starch ether can slightly, but not obviously, extend the setting time of cement mortar. Hydroxypropyl methyl cellulose ether has the greatest impact on the mechanical properties of ordinary dry-mixed mortar, followed by redispersion emulsoid powder, starch ether, and bentonite. As the water retention increases, the setting time of the mortar also increases. The use of water as a thickening material has a retarding effect on the mortar, increases the water-retention rate, and increases the retarding effect. Moreover, increasing the content of the chemical admixtures decreases the strength of cement mortar.

Effect of Pressure on Expanded Polystyrene (EPS) Dry Mix Mortar Block

Nowadays, there is more demand than supply on the uses of material in the construction. Thus, the need to use alternative materials should be widely used and practiced among the construction and development to pro-longed the material for future generation supply. The objective of this study is to investigate the effect of different pressure exerted between 700 kPa, 900 kPa and 1100 kPa to the replacement of Expanded Polystyrene (EPS) at 20 %, 25 %, 30 %, 35 % and 40 % of sand replacement in achieving target strength of 5 N/mm² to 7 N/mm² of EPS dry mix mortar block. The tests were conducted at 7 and 28 days of curing with various replacements of EPS in the dry mix Besides, the study is also to identify the density of EPS Dry Mix Mortar Block due to pressure exerted (700 kPa, 900 kPa and 1100 kPa) as a lightweight block. From the result that obtained, it was found that the most suitable pressure to be exerted is 700 kPa since it was the less required pressure needed to achieve the target strength of 5-7 N/mm² at 20 % of EPS replacement which is 5.74 N/mm². Besides, it was shown that the increase of pressure exerted to the EPS dry mix mortar block also will increased its density thus resulted in higher compressive strength.

Statistical analysis of test methods to evaluate rendering surface properties

Abstract The objective of this study is to discuss the results of two test methods used to evaluate rendering surface properties: the superficial tensile strength (STS) and the pendulum rebound hammer (which provides the rebound index - RI), besides evaluating, additionally, the tensile bond strength (BS). The studied variables were the type of mortar (job-site mortar and dry-mix mortar) and the render moisture at the time of testing (in four contents). For each test, a minimum of 45 determinations was planned per analyzed situation, totaling 1411 valid results, which allowed a consistent statistical analysis and an in-depth discussion of the methods. The STS and RI tests were sensitive at a 95% confidence level to differentiate mortars from different strengths and were therefore approved for this evaluation. The most significant effect in all statistical models tested was the type of mortar. The variable moisture condition of the render was significant only for the results of STS and BS. In such cases, tests performed with wet or saturated renders presented much lower strength results compared to those carried out with air- dried renders. It was possible to obtain a significant correlation between STS and BS, with a high coefficient of determination.

Performance Enhancement of Polycondensate‐Based Superplasticizers by Encapsulation

AbstractA cost‐effective and robust encapsulation system for chemical admixtures with delayed release mechanisms for construction materials like dry mix mortars is presented. Based on supplementary cementitious materials, a superplasticizer was encapsulated in matrix‐based encapsulations. Subsequently, the particle characteristics of the agglomerates and the release behavior of the superplasticizer were examined. The main objective of this research was to prove the functionality of such encapsulations for the future use in construction materials. The results obtained indicate that the performance of construction chemicals could be improved by encapsulation and controlled release for the future development of new construction materials. Furthermore, material characteristics of the supplementary cementitious material like the incline to excessive dusting or the materials density were improved by encapsulation.

Influence of temperature and moisture on the shelf-life of cement admixed with redispersible polymer powder

The shelf-life of cement blended with redispersible polymer powder (RDP) used in drymix mortars was studied after exposure to an atmosphere of elevated temperature (40±1°C) and moisture (90±3% RH) simulated in a climate chamber. As RDP samples, ethylene–vinylacetate and carboxylated styrene–butadiene were used. The behaviour of the cement/RDP blends was studied with respect to film formation of the RDPs and the mechanical properties of the resulting mortars. It was found that the presence of RDP decelerates the prehydration of cement in humid environment and thus improves its shelf-life. At the same time, cement triggers a partial premature film formation from RDP powder during aging. Furthermore, mortars containing aged cement/RDP blends retained their mechanical properties much better than mortars casted from cement which had been aged individually. Apparently, RDP can protect cement from rapid aging.

Evaluation of crumb rubber as aggregate for automated manufacturing of rubberized long hollow blocks and bricks

Waste tire rubber is a promising lightweight aggregate for building products that enhances their thermal and acoustic properties. Even the environmental benefits of its use are evident, higher cost and significant changes in compressive strength and workability hinder its widespread adoption. This article examines the use of crumb rubber (CR) as aggregate in dry-mix mortars to produce rubberized long hollow blocks and bricks using automated brick machines. CR was incorporated over a range of 10–40% with water/cement ratio varying from 0.7 to 0.9. The production of rubberized bricks exhibited better performance than long hollow blocks in factory trials. Tests showed important deformations and drastic reduction in compressive strength, especially for crumb rubber percentages greater than 20%. Due to this and the high cost of CR, caution must be taken with the design of new rubberized building products to make sure they are profitable.

Precast architectural tiles produced by double-layer casting method

This work aims to develop a technology with an instant demoulding ability for making precast architectural tiles with an aesthetically pleasing appearance. To achieve this, double-layer composite consisting of a wet-mixed self-compacting glass mortar as the surface-layer and a dry-mixed mortar as the base-layer was designed. The performance of the surface-layer prepared with recycled glass cullet with different particle sizes, and the effects of aggregate types and contents on the base-layer mortar were investigated. The results suggest that the non-porous nature and smooth surface of the glass cullet decreased the water absorption and reduced the strength of the mortars. The flexural and pull-out strength results demonstrated that all the architectural tiles produced exhibited good interfacial adhesion between the two layers and complied with the standard requirements for “Terrazzo tiles” for internal and external applications.

The Promotion Strategy of Green Construction Materials: A Path Analysis Approach.

As one of the major materials used in construction, cement can be very resource-consuming and polluting to produce and use. Compared with traditional cement processing methods, dry-mix mortar is more environmentally friendly by reducing waste production or carbon emissions. Despite the continuous development and promotion of green construction materials, only a few of them are accepted or widely used in the market. In addition, the majority of existing research on green construction materials focuses more on their physical or chemical characteristics than on their promotion. Without effective promotion, their benefits cannot be fully appreciated and realized. Therefore, this study is conducted to explore the promotion of dry-mix mortars, one of the green materials. This study uses both qualitative and quantitative methods. First, through a case study, the potential of reducing carbon emission is verified. Then a path analysis is conducted to verify the validity and predictability of the samples based on the technology acceptance model (TAM) in this study. According to the findings of this research, to ensure better promotion results and wider application of dry-mix mortar, it is suggested that more systematic efforts be invested in promoting the usefulness and benefits of dry-mix mortar. The model developed in this study can provide helpful references for future research and promotion of other green materials.

Effect of Different Grain Grading of Manufactured-Sands on Properties of Dry-Mixed Mortar

Manufactured-sands were divided into eight groups according to the grain size by the use of sieving method and the eight groups sands were made into eight groups dry-mixed mortar. Compressive strength and flexural strength of the eight groups mortar and the bonding strength of the mortar to polystyrene and ceramic tile were investigated in this paper, in order to know the influence of the grain grading of manufactured-sands on the properties of dry-mixed mortar. The test results showed that the compressive strength, flexural strength and the ratio of bending-compressive strength of dry-mixed mortar increased with the decreasing of the content of the finer sands and the increasing of the content of the coarser sands. The bonding strength of the mortar to polystyrene and ceramic tile first increased and then decreased with the decreasing of the content of the finer sands and the increasing of the content of the coarser sands. The results of this study illustrate that the performances of dry-mixed mortars with manufactured-sands of four group and five group are good.

Dry-Mixed Mortar Control System Based on Fieldbus and PLC

A design of dry-mixed mortar control system based on Fieldbus and PLC was introduced in this paper. A scheme of totally integrated automation, which includes S7-300 PLC, PROFIBUS-DP Fieldbus, touch panel and etc., was proposed. Firstly, control demands and process of this system were described; secondly, hardware configuration and software design were illustrated as well. By using large-scale PLC and field level network - PROFUBUS-DP, the motions of electric motor actuators or hydraulic cylinder actuators are running well, and all sections in the process flow, like hoist, well-distributed vibration, mixing, unloading, etc can all be implemented in time and in place. Though the actual running of the control system it has been proved that the fully integrated automation production of dry-mixed mortar can be thoroughly realized.

A Study of Basic Properties of Cellulose Ether Modified Dry-Mixed Mortar

In this paper, the quality evaluation indexes of cellulose ether (CE) modified dry-mixed mortar are proposed by the comparison of properties of contrast mortar. The technical indexes of CE modified mortar include water retention, anti-sliding value, time difference of final set and the tensile bond strength ratio which give a good guidance for the application effect evaluation of cellulose used in dry-mixed mortar.

System for the Management of Raw Materials Based on RFID Technology

The system presented in this article has been developed in order to solve several problems occurred during uploading raw materials in the storage tanks of a dry mix mortars plant and to keep an accurate material balance of raw materials introduced in the production process. The proposed approach was to implement a UHF, RFID (Ultra High Frequency, Radio Frequency Identification Device) system consisting of tags on the intake of the uploading pipes and outlets of the transportation trucks and a UHF, RFID Writer/Reader with four antennas in the proximity of uploading and to create an associate database for tracking the uploaded materials. The newly developed system has been successfully operationally tested in a dry mix mortar plant nearby Ploiesti.

Effect of heat treatment on the dispersion performance of casein superplasticizer used in dry-mix mortar

The influence of heat exposure during production of casein on its plasticizing effectiveness was investigated. A model self leveling underlayment (SLU) formulation was used to assess the dispersing power of casein. It was found that elevated temperature and long exposure times can induce chemical changes in the casein proteins which reduce their performance. Particularly, crosslinking accompanied by partial decomposition (denaturation) of the casein biopolymer as evidenced by fast protein liquid chromatography and gel permeation chromatography was found to be responsible for reduced dispersing power. As an optimum drying condition, a temperature of 110°C and a short exposure time of up to 2h are recommended. Under this condition, the wet casein rapidly releases its water while maintaining its full dispersion power. Understanding the temperature and exposure-time dependent behavior of casein proteins can help to produce more consistent casein qualities.

Design of the Dry-Mixed Mortar Truck in Avoiding Segregation

The way of dry-mixed mortar air-sliding has many advantages，such as improving transport efficiency, ensuring cement quality. But, dry-mixed mortar air-sliding may occur segregate, this phenomenon serious break the original ratio of cement, risking quality of cement[2]. This article suggested a new model of discharge opening with multi-holes, this model can allow dry-mixed mortar flow out at different height, and control the rate of flux in each port to keep mortar equally, this model eliminated the non uniforms caused by different height, eliminated the affection of segregate, ensure the quality of the cement.

Study on Key Techniques of Control System for Dry-Mixed Mortar Production Line

As a new energy-saving and environmental protection building material, dry-mixed mortar has been promoting actively in China. The key techniques of control system for dry-mixed mortar production line were introduced in this paper, which was mainly based on PLC and smart weighing instrumentation. Firstly, the technology process and control demands were presented. Secondly, control system configuration, control strategy were proposed in detail. Finally, the key intelligent adjust algorithms were described as well. The practical operation verifies that the control system is highly reliable and stable, and it greatly enhances the level of automation and weighing accuracy of the raw material and meets the equipments requirements of energy-saving and green running.

High Performance and Low Cost Compound Admixture of Expanded Perlite Powder/Redispersible Polymer Powder for Dry-Mixed Mortar

Since modern architectural technology has set a new standard for toughness of mortar, expensive polymer admixture has been used to modify dry-mixed mortar currently. But high cost critically restricted popularization of dry-mixed mortar. A new expanded Perlite powder- redispersible Polymer powder Compound dry-mixed mortar Admixture (PPCA) was researched in this paper. The research has indicated that PPCA showed synergistically optimized effect. There was the best modification effect when expanded perlite powder/redispersible polymer powder rate was 2 and admixture/cement rate was 0.15. The Ratio of Compressive strength to Flexural strength (RCF) declined to less than 3 when compressive strength of mortar staying above 10MPa. Moreover, cost of this compound admixture only was 1/3 of redispersible polymer powder admixture of the same performance. Meanwhile, this PPCA can improve water retention and increase softening coefficient of mortar to above 1.