Mortar Expansion Research Articles

Sulfate attack on portland-dolomite cement exposed to sodium sulfate solution at 5 ℃ and 20 ℃

The purpose of the study is to investigate the sulfate resistance of portland-dolomite cement (PDC) with varying dolomite contents, when exposed to sodium sulfate solution at 5 ℃ and 20 ℃. Visual appearance, expansion, mass change, and compressive strength of PDC mortars were tested, and XRD, FTIR, and SEM analyses were conducted to examine deterioration products and microstructure. Results indicate that at 20 ℃, the incorporation of 10 % dolomite in PDC had a negligible impact on sulfate resistance, whereas higher dolomite replacements of 20 % and 30 % notably diminished it. In contrast, exposure at 5 °C led to more severe deterioration in all PDC samples, regardless of dolomite content, and the higher dolomite content, the poorer resistance to sulfate attack. The increased formation of ettringite and gypsum resulted in reduced sulfate resistance of PDC at 20 ℃. However, at 5 ℃, the presence of dolomite significantly promoted the formation of thaumasite at later stages, which caused initial ettringite and subsequent late-stage thaumasite sulfate attack, ultimately leading to the failure of PDC. The findings suggest that PDC should be carefully considered when used in sulfate-rich environments, particularly at low temperatures.

Prediction of alkali–silica reaction expansions of mortars containing glass waste

The majority of existing findings regarding expansion (EXP) risks in concretes containing waste glass stem from experimental studies. There is a need for rapid assessment methods to ensure safer recycling of glass waste in cementitious composites. In this study, an artificial neural network (ANN) model was developed to accurately predict alkali–silica reaction EXP/mitigation resulting from the integration of glass waste in mortars. The analysis considered glass incorporation either separately as waste glass powder (WGP) and waste glass aggregates (WGAs), or in combination, at contents of up to 100% for WGA and 30% for WGP. A set of 175 mixtures was analysed, considering five distinct variables, which encompassed different mix proportions, involving varying components of cement, natural aggregates, WGP and WGA, in addition to the duration of environmental exposure. The results show that the EXP of WGA mortars decreased with the increased incorporation of WGP. The EXP values obtained from validation and experience confirm the high accuracy of the developed ANN model, with validation coefficients reaching up to 98.061% and a small value of the mean square error.

Impact of internal pre-damage due to drying shrinkage under various humidity conditions on DEF expansion in cement paste and mortar

This study explores the impact of internal pre-damage from early drying shrinkage on the delayed ettringite formation (DEF) expansion behavior of cement-based materials subjected to high-temperature processes. Specimens of cement paste and mortar with water-cement (W/C) ratios of 0.4, 0.5, and 0.6 were characterized after curing under relative humidity (RH) conditions of 50, 70, and 100 for 56 days. The parameters assessed were drying shrinkage, dynamic elastic modulus, and free water content. Subsequent DEF expansion over time was quantified, and the underlying mechanism was analyzed using XRD and SEM techniques after 270 days of underwater curing. Results indicate that: (1) a lack of adequate early curing humidity significantly reduces the dynamic elastic modulus with more than a 10% drop in cement paste following 56 days at RH50; (2) a higher W/C ratio and lower early curing humidity lead to more internal damage due to shrinkage, thereby promoting DEF expansion; (3) drying intensifies internal pre-damage in the interfacial transition zone (ITZ), causing an earlier deterioration of DEF expansion in mortar compared to cement paste. However, the presence of aggregates constrains this, leading to lesser DEF expansion in mortar; (4) dynamic elastic modulus changes as measured by ultrasonic methods can quantitatively characterize the extent of deterioration caused by DEF expansion, thus offering a tool for non-destructive testing and DEF expansion deterioration analysis.

Mitigation mechanisms of alkali silica reaction through the incorporation of colloidal nanoSiO2 in accelerated mortar bar testing

Alkali Silica Reactivity (ASR) is a prominent issue concerning the durability of concrete structures. To mitigate this deleterious reaction, a widely accepted practice involves replacing significant cement portions with supplementary cementitious materials (SCMs). Given the scarcity of high-quality SCMs, nanoSiO2 exhibits considerable promise, given its minimal dosage requirement for ASR mitigation, whether applied independently or in conjunction with other SCMs. This research investigates the efficacy and underlying mechanisms of colloidal nanoSiO2 (CNS) in accelerated mortar bar tests according to the ASTM C1260 method. The experimental methodology incorporated two distinct forms of CNSes, CNS1 and CNS2, with average particle sizes of 14 and 67 nanometers, respectively. The outcomes are subsequently compared to the ASR performance of a sample containing silica fume (SF). The results demonstrate that the CNS size is pivotal in governing the pozzolanic reaction rate. The CNS2 and SF exhibited analogous pozzolanic reactions, displaying superior effectiveness in promoting pozzolanic activity compared to the CNS1. At a 4.75% cement replacement level, the CNS2 achieved a 78% reduction in mortar expansion over the control sample. The CNS1, when utilized at 4.75% and 7% cement replacement levels, yielded expansion reductions of 38% and 43%, respectively. It was found that the inclusion of the CNS can increase the porosity of mortar and contribute to silica dissolution from the reactive aggregates. Meanwhile, the addition of CNS improved the bulk resistivity of mortar by 200%-600% and flexural strength by 25%-62% based on the replacement levels and the CNS types. Moreover, improvements in calcium hydroxide consumption and alkali binding in the ASR gel were observed during the test, indicating the underlying mechanisms for expansion mitigation. These research outcomes can accelerate the CNS utilization to mitigate the ASR in practical field applications.

Experimental Study on Modification of Grouting Material for Joints of Prefabricated Buildings

In order to apply grouting material to the joints of fabricated buildings and make it meet the performance demands of low shrinkage, strong bond, and high toughness of joint materials for prefabricated buildings, the expansion agent (EA), neoprene latex (NL), and rubber particles (RP) were used to modify the grouting material, and the effects of different dosages of the three components on the working performance, mechanical properties, and expansion or shrinkage properties of the grouting material were investigated. The results show that the EA decreases the flexural strength-to-compressive strength ratio (FCR) of the grouting material and enhances the vertical expansion rate and bond strength. The dosage of EA and the curing conditions have a significant effect on the expansion rate of the hardened grouting material. The grouting material can still maintain its 0.0022% free expansion rate with a 7% EA dosage at 120 d. The NL significantly inhibits the vertical expansion of the fresh mortar but inhibits the drying shrinkage of the grouting material after hardening, improves the FCR and bond strength; the 7 d bond strength under a 5% NL dosage can reach 4.27 MPa. The RP inhibits the vertical expansion of the fresh mortar and the drying shrinkage after mortar hardening; with the increase of its dosage, the bond strength of the grouting material increases first and then decreases, the 28 d FCS of the grouting material peaked at 0.173 at 10% dosage.

Effects of dosage and reactivity of modified dolomite dust waste on mechanical properties and shrink-resist of mortar

Dolomite dust waste (DDW) has the potential to be used as an expansive agent for mortar due to its richness in magnesium and calcium. This paper reports the possibility of developing low-cost expansive agent for mortar using DDW through various activation methods. The changes in the physicochemical properties of the activated DDW and the shrinkage resistance, flexural strength, and compressive strength of the composite mortar prepared by partially replacing cement were systematically investigated. The hydration products and microstructure of DDW-composite mortar were investigated by XRD and SEM-EDS techniques. This study confirmed the feasibility of activated DDW as mortar expansion agents and the necessity of activation treatment for the resourceful use of DDW. The results showed that the activation treatment enhanced the activity of DDW, and the higher hydration reactivity significantly improved the shrinkage resistance and mechanical properties of composite mortar compared to raw DDW. The addition of 10% C800 DDW (thermal at 800 °C) showed a full-age compensatory effect on the volume shrinkage of the mortar. Substituting cement partially with 10% C900 DDW (thermal at 900 °C), the volume expansion rate of composite mortar after 28 d of standard curing exhibited 24.49% higher than normal, and its compressive strength (40.1 MPa) at 60 d exceeded 6.40% than normal mortar (37.7 MPa). The drying shrinkage of G30-10 (mechanically activated) and A0.1-10 (chemically activated) at 60 d resulted in 6.23% and 5.19% lower than normal mortar, respectively. Microanalysis revealed that the addition of DDW promoted the generation of C-M-S-H gels. The findings are instructive for the preparation of green and low-cost mortar expanders using DDW.

Impact of Aggregate Grain Size on ASR-Induced Expansion.

Alkali-silica reaction (ASR) is a sequence of complex chemical processes, resulting in the formation of alkali silica gels with high swelling ability. ASR leads to the expansion of concrete and the degradation of its microstructure. The susceptibility of aggregates to alkali reaction depends, among other factors, on the type and origin of the aggregate, the presence of reactive forms of silica, the mineral composition, and the geometric properties of the aggregate, such as shape and grain size. This study aimed to investigate the impact of the grain size of polymineral post-glacial gravel aggregate, originating from the northern regions of Poland, on its susceptibility to ASR. The expansion of mortars made from polymineral aggregate and the cracking of grains and cement matrix due to the occurring reactions were analyzed. Based on the conducted research, it was observed that the expansion of mortars depends on the grain size of the aggregate. It was demonstrated that the fraction of reactive aggregate generating the most significant elongation of mortars is in the range of 1.0-2.0 mm. The reaction of silica with alkalis continued until the depletion of reactive components in the aggregate. The relationship between the progress of corrosive processes and the grain size of the aggregate was evident in the form of different linear elongation increments of mortars over time. The expansion of mortars was caused by the swelling ASR gel, inducing stress in the grain and the surrounding cementitious paste.

Influences of cement asphalt emulsified mortar construction on track slab geometry status

PurposeThe construction of cement asphalt (CA) emulsified mortar can obviously disturb the slab status after the fine adjustment. To decrease or eliminate the influence of CA mortar grouting on track slab geometry status, the effects of grouting funnel, slab pressing method, mortar expansion ratio, seepage ratio and grouting area on China Railway Track System Type (CRTS I) track slab geometry status were discussed in this paper.Design/methodology/approachCombined with engineering practice, this paper studied the expansion law of filling layer mortar, the liquid level height of the filling funnel, the pressure plate device and the amount of exudation water and systematically analyzed the influence of filling layer mortar construction on the state of track slab. Relevant precautions and countermeasures were put forward.FindingsThe results showed that the track slab floating values of four corners were different with the CA mortar grouting and the track slab corner near CA mortar grouting hole had the maximum floating values. The anti-floating effect of “7” shaped slab pressing device was more efficient than fixed-joint angle iron, and the slab floating value could be further decreased by increasing the amount of “7” shaped slab pressing devices. After CA mortar grouting, the track slab floating pattern had a close correlation with the expansion rate and water seepage rate of CA mortar over time and the expansion and water seepage rate of the mortar were faster when the temperature was high. Furthermore, the use of strip CA mortar filling under the rail bearing platform on both sides could effectively reduce the float under the track slab, and it could also save mortar consumption and reduce costs.Originality/valueThis study plays an important role in controlling the floating values, CA mortar dosage and the building cost of projects by grouting CA mortar at two flanks of filling space. The research results have guiding significance for the design and construction of China's CRTS I, CRTS II and CRTS III track slab.

Study on the Influence of Magnesite Tailings on the Expansion and Mechanical Properties of Mortar.

To reduce the mining of high-grade magnesite and solve the environmental pollution caused by magnesite tailings, magnesite tailings were used to produce MgO expansion agent (MEA), and a detailed study of its performance was carried out in this study. Firstly, the effects of different calcination times on the calcination products, the specific surface area, and the activity of MEA were analyzed. Then, the MEA produced by calcinating at 950 °C for 1 h was taken as the research object, and the effects of its content on the expansion performance, compressive strength, and flexural strength of the mortar were studied. The results showed that the decomposition of magnesite tailings after high-temperature calcination produced MEA, and the longer the calcination time, the lower the activity. The calcined tailings could compensate for the shrinkage of the mortar, and the expansion increased with the increase in curing temperature. What is more, when the content was less than 8%, the hydration of MEA filled the pores and improved the compactness, so the strength of the mortar increased with the increase in the expansion agent content. When the dosage was greater than 8%, excessive expansion increased the porosity, causing harmful expansion of the mortar and damaging its integrity, leading to a decrease in strength. Fly ash reduced the expansion of mortar, and after adding 30% fly ash, the expansion decreased by 20.0-36.1%, and the ability to suppress expansion decreased with the increase in curing temperature.

A rapid-hardening cement emulsified asphalt (CEA) mortar prepared from magnesium phosphate cement

Cement emulsified asphalt (CEA) mortar is the key component material of high-speed railway track slabs, and it is prone to damage under the coupling effect of environment and load. For severely damaged CEA mortar, the strategy of replacing the filling layer is required. However, the daily idle period of high-speed railways is extremely short in China, which makes Portland cement-based CEA mortar unable to meet the time and material performance requirements of high-speed railway maintenance. Therefore, a novel magnesium phosphate cement-based CEA (MEA) mortar is prepared in this study, and the effects of key parameters on its fresh properties, strength, and durability are systematically investigated. A MEA mortar with a setting time within 30 min and a compressive strength of 15–45 MPa is developed. Increasing the emulsified asphalt to cement (EA/C) ratio reduces the strength, water resistance, and frost resistance of MEA mortars, mainly because increasing the EA/C ratio leads to decreased reaction products and increased porosity. Meanwhile, increasing the EA/C ratio also leads to a higher volume expansion of the MEA mortar. In addition, adding an appropriate amount of emulsified asphalt with low water content can increase the setting time and failure strain of the MEA mixture compared with the plain magnesium phosphate cement component, and it performs better than emulsified asphalt with high water content. This study demonstrates acceptable performance of MEA mortar prepared with appropriate EA/C ratio and type of emulsified asphalt, which provides an alternative material for track slab maintenance.

Inhibitory mechanism of fly ash on alkali-silica reactivity of siliceous rock fine aggregate: A case study of Yangxi concrete dam

The fine aggregate of siliceous rock has the advantages of high production efficiency, stable yield and low construction and transportation cost. The Yangxi concrete dam was firstly apply siliceous rock as fine aggregate to a large concrete project of three million m3. However, siliceous rock aggregate has high SiO2 content, which is easy to trigger alkali-silicate reactivity. To investigate the alkali-silica reactivity characteristics of siliceous rock fine aggregate and its inhibitory measures, in this work, we used fly ash, ordinary silicate cement, and siliceous rock fine aggregate to prepare cement mortar. The effects of fly ash admixture on the expansion rate, as well as the flexural and compressive strength of the mortar were investigated by the mortar rod rapid method and mechanical tests. The inhibition mechanism of fly ash on the siliceous rock fine aggregate was analyzed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) techniques. The results showed that the addition of 30 % fly ash to the siliceous rock mortar could effectively limit the mortar expansion and its late strength growth was the most rapid. Compared to siliceous rock mortar without fly ash, the FA30 specimen mixed with 30 % fly ash had a denser structure, the hydration products at the ITZ were more closely arranged, and the C-A-S-H gel with a low calcium-silica ratio was generated internally, which could effectively inhibit the ASR of the siliceous rock fine aggregate.

Unidirectional penetration approach for characterizing sulfate attack mechanisms on cement mortars and pastes

Degradation of cementitious materials by sulfate ions is commonly classified into chemical and physical sulfate attack. So-called “physical” attack dominates in many field situations, but laboratory testing focuses on “chemical” attack under full-immersion. This paper presents a new setup which looks at sulfate ion ingress under unidirectional capillary action, as a first approach to field conditions. Here, a high concentration of sulfate ions and w/c and Portland cement were used to accelerate degradation to see if the approach is feasible. The radial expansion and appearance of mortar and paste samples were tracked over time. Periodically, profiles of sulfate ingress and phase assemblage were studied in the SEM and by X-ray diffraction. The results show that physical and chemical sulfate attack occur in different areas of the same sample. The approach shows potential to uncover the mechanisms involved in sulfate attack including both “chemical” and “physical” aspects of the degradation process.

New perspective to improve the sulfate attack resistance of mortar by coral sand

Sulfate attack is one of several chemical mechanisms of concrete deterioration. It can cause expansion, crack and mechanical property degradation of concrete due to the formation of ettringite and gypsum. A new perspective is proposed in this study to improve the sulfate attack resistance of mortar by considering the porosity characteristic of coral sand. The role of coral sand in the cement mortar when it is exposed to sulfate solution is explored comprehensively. Two kinds of sands, standard sand and coral sand, are used. The mortar sample is exposed to 5 wt % Na2SO4 solution after a hydration period of 28 days. Some supplementary cementitious materials (SCMs), such as coral sand powder, limestone powder, fly ash, are used in this study to replace cement partially. After a certain exposure time, the visual appearance, mechanical properties, length and mass change, phase composition and microstructure development of the cement mortar are investigated. The results show that the cement mortar made with coral sand has a much better resistance to sulfate attack than that made with standard sand. Although sulfate attack happens inevitably in coral mortar, the use of coral sand can largely mitigate the loss of properties of mortar, such as strength, mass and linear change, etc. In particular, after 1 year of exposure, the use of coral sand in mortar largely reduces the expansion of mortar due to sulfate attack; the linear change of coral mortar is only one-seventh in that of normal mortar. Formation of ettringite in empty spaces of coral sand and other voids explains why coral mortar has better properties than normal mortar under accelerated sulfate attack. The achievement of this study can largely improve the resistance of marine concrete to chemical attack.

Experimental and numerical study of long-term alkali-silica reaction (ASR) expansion in mortar with recycled glass

Recycled glass has been demonstrated to be a sustainable alternative for sand in concrete, which can tackle the stockpiling of waste glass and shortage of natural aggregate. However, alkali–silica reaction is the major impediment to its wide adoption where more research is required. This paper examined the long-term ASR expansion of mortar containing glass from experimental and numerical analyses. In the experimental study, the effect of glass size (0.15–0.3 mm, 0.3–0.6 mm, 0.6–1.18 mm, 1.18–2.36 mm, 2.36–4.75 mm), glass content (25%, 50%, 75%, 100% by mass) and curing temperature (38 °C, 60 °C 80 °C) were investigated. The accelerated ASR expansion tests were conducted in the elevated temperature and boosted alkali supply. Experimental results showed that the size fraction 1.18–2.36 mm caused the highest ASR expansion, and the size fractions smaller than 0.6–1.18 mm was found to be innocuous. Besides, ASR expansion increased as glass content increased. Furthermore, ASR kinetic was slower and final expansion reduced when temperature decreased. To provide insights into the ASR expansion behaviours, a novel meso-scale chemical-mechanical model was proposed in this study. In the numerical model, the tested specimens were modelled as a three-phase composite including the matrix, glass aggregate and interfacial transition zone. The mechanical and chemical components in the model were calibrated and validated by uniaxial compression and ASR expansion tests. The validated model not only can accurately predict the ASR expansion but also reveal that internal damage became more homogeneous with increasing content of reactive aggregate.

Deterioration Process of Cementitious Material Properties under Internal Sulphate Attack

As one of the important factors affecting the structural durability of cementitious materials, sulphate erosion not only reduces the service life of the material but also poses a threat to the structural safety of the project. At present, scholars around the world have conducted extensive research on topics related to external sulphate attacks and have achieved fruitful results. However, the process and mechanism of attack degradation of the gelling material are not clear. In this paper, gypsum sand was introduced into the mortar. The effects of gypsum content, gypsum particle size and curing temperature on physical properties such as expansion and strength of specimens were investigated. X-ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC), Scanning Electron Microscopy (SEM) and energy dispersive spectrometry (EDS) were used to analyse specimens’ phase composition and microstructure evolution at different attack ages. Finally, cementitious materials’ degradation process and mechanism under internal sulphate attack (ISA) were analysed. Through the above research, the following main conclusions are drawn: (1) The swelling rate of cement mortar specimens all increased with the increase of gypsum dosing; (2) The expansion of cement pastes and mortars does not increase with the increase in curing temperature; (3) The gypsum particle sizes are smaller, the expansion of mortar specimens is larger, and the loss of compressive and bending strength of mortar specimens is large; and (4) The main reaction product of ISA is Ettringite (AFt). The gypsum formed during the ISA process does not cause expansion, while AFt is the main reason for the destruction of the cementitious material.

Efficient utilization of waste CRT glass in low carbon super-sulfated cement mortar

This study developed a novel low carbon super-sulfated cement (SSC) mortar prepared with multiple types of solid wastes, including phosphogypsum and cathode ray tube (CRT) panel glass. The properties of this cement mortar were compared with the OPC/river sand counterpart with respect to durability and environmental performance. The pozzolanic reaction between the active surface of the CRT glass and matrix in the SSC improved the interface performance. The SSC mortar also showed lower water sorptivity associated with the denser microstructures, the finer pore size, and the lower connectivity of pores when compared to the conventional counterpart. Moreover, the high bulk electrical resistance of SSC mortar inhibited ions transport and further improved the durability. Meanwhile, the high sulfate environment and superior uptake ability to alkali ions of the generated C-A-S-H can effectively mitigate the alkali silica reaction-induced expansion in SSC mortar, even when 100% CRT glass aggregates were incorporated. However, the higher volume of mesopores in SSC than in OPC caused a higher drying shrinkage. The SSC provided a more promising outlet for the recycled CRT glass compared to OPC cementitious system in terms of environmental impacts (leaching and carbon footprint). The joint use of low carbon SSC and CRT glass can not only reduce 80% CO2 emissions by realizing the valorization of multiple types of solid wastes but also achieve better durability over the OPC system.

Synergistic effect of waste glass powder and fly ash on some properties of mortar and notably suppressing alkali-silica reaction

In this study the mitigation influence of incorporating waste glass powder (G) and class F fly ash (F) in mortar as partial cement replacement on the alkali-silica reaction (ASR) between reactive aggregate and alkali contents of cement were investigated. Waste G and F replaced cement separately and together on mass basis at 10%, 20%, and 30%. The unit weight (28 days), water absorption, porosity, compressive, and flexural strength tests were conducted at 28- and 90-day water curing time on 40×40×160 mm prismatic hardened samples and flow table test on fresh mortar. There was a slight reduction of the unit weight, an increased workability, and decreased water absorption and porosity; a little reduction of the compressive strength and flexural strength were seen after the tests. In addition, the expansions of mortar were measured up to 90 days. When 14 days expansions were considered according to ASTM C1260, addition of waste G and F separately reduced the expansion that occurred due to ASR. However, the mixture containing 15% waste G and 15% F together (GF-30) exhibited the lowest expansion in the order of 0.02% which was far lower than 0.10%. The higher replacement ratio of waste G and F together and separately caused lower expansion in mortar.

The impact of modified cement with a special additive on construction mortar deformations

The study is devoted to the modification of 42.5 class ordinary Portland cement with a 10% special expanding additive (cement powder and gypsum in a 40:60 percentage ratio), and the impact of this cement on mortar is determined. Using modified cement and multi-fraction quartz sand in a ratio of 1:3, prism-shaped samples with a size of 4x4x16 cm were fabricated, and left in a water bath for 24±2 hours after formation. After one day of curing, the samples were demolded, their linear dimensional change was verified using an indicator, and they were then submerged in water. After three, seven, and 28 days of curing, the samples’ changes in linear dimensions were examined again using an indicator. It has been revealed that introducing a 10% specially developed expansion additive to the composition of ordinary Portland cement also contributes to the maximum expansion of the construction mortar at 3–7 days of hardening. The expansion percentage of the 28-day curing time is very little different from the 7-day indicator. Considering the data on the linear dimensional change of the test samples, we can conclude that the modification of cement with the synthesized additive allows the production of non-shrinkable, expansive construction mortars and concretes, which are currently being studied.

Effect of environmental conditions on the volume deformation of cement mortars with sewage sludge ash

Sewage sludge ash (SSA) is obtained from wastewater sludge incineration, and it can be recycled in cement-based materials. The environmental conditions show significant influence on the volume deformation of cement-based materials with SSA. So in this study, the effect of environmental conditions on the volume deformation of mortars with SSA was investigated, and the underlying mechanism was preliminarily studied with isothermal calorimetry, X-ray diffraction (XRD) and thermogravimetry (TG). The results indicated that, under seal condition, SSA caused obvious expansion after the rapid shrinkage at very early age, and reduced the 28d autogenous shrinkage of mortars. Under drying condition, the addition of SSA enlarged the drying shrinkage of mortars. Under water immersed condition, the mortars expanded before the age of 7d, and more SSA led to more obvious expansion. The addition of SSA resulted in more ettringite formed in mortars under sealed and water immersed conditions, leading to the expansion of mortars. The findings of this study could help to control the volume deformation of mortars with SSA.

Mixture Design and Mechanical Properties of Recycled Mortar and Fully Recycled Aggregate Concrete Incorporated with Fly Ash.

Recycled aggregate concrete (RAC) is a sort of green, low carbon, environmental protection building material, its application is of great significance to the low carbonization of the construction industry. The performance and strength of RAC are much lower than natural aggregate concrete (NAC), which are the key factors restricting its application. Class F fly ash is a cementitious material that is considered environmentally hazardous. In this paper, appropriate water-binder (w/b) ratios were found through a mortar expansion test at first. The compressive strength of recycled mortar incorporated with class F fly ash was further studied. On this basis, the mechanical properties of nine groups of fully recycled aggregate concrete (FRAC) with a w/b ratio of 0.3, 0.35, and 0.4, and fly ash replacement ratios of 0, 20%, and 40%, were studied. The influence of the w/b ratio and fly ash replacement ratio on mechanical properties was analyzed and compared with previous research results. In addition, the conversion formulas between the splitting tensile strength, flexural strength, and compressive strength of FRAC were fitted and established. The research results have a certain guiding significance for the mixture design of FRAC and further application of class F fly ash.